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Bibliography on: Current Literature — Recent Full Contents

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Robert J. Robbins is a biologist, an educator, a science administrator, a publisher, an information technologist, and an IT leader and manager who specializes in advancing biomedical knowledge and supporting education through the application of information technology. More About:  RJR | OUR TEAM | OUR SERVICES | THIS WEBSITE

RJR: Recommended Bibliography 20 Jan 2019 at 01:35 Created: 

Current Literature — Recent Full Contents

Current Literature: Full, recent table-of-contents listings for a few selected journals.

Created with PubMed® Query: 2018[PDAT] AND ( 0003-0147[issn] or 0006-3568[issn] or 0006-8977[issn] or 0012-1606[issn] or 0014-3820[issn] or 0022-0930[issn] or 0022-2844[issn] or 0025-9241[issn] or 0028-0836[issn] or 0031-8248[issn] or 0033-5770[issn] or 0039-3681[issn] or 0047-2484[issn] or 0066-4154[issn] or 0066-4162[issn] or 0066-4197[issn] or 0066-4227[issn] or 0068-6735[issn] or 0071-3260[issn] or 0085-0748[issn] or 0090-4996[issn] or 0095-134x[issn] or 0165-0157[issn] or 0168-6445[issn] or 0168-6496[issn] or 0168-9525[issn] or 0169-3867[issn] or 0169-5347[issn] or 0169-6149[issn] or 0269-7653[issn] or 0343-8651[issn] or 0346-8313[issn] or 0378-2697[issn] or 0393-9375[issn] or 0394-9370[issn] or 0737-4038[issn] or 0743-4634[issn] or 0923-2508[issn] or 0947-5745[issn] or 0949-944x[issn] or 0960-8788[issn] or 0962-8436[issn] or 0966-842x[issn] or 0967-3849[issn] or 0972-7736[issn] or 0972-8422[issn] or 1010-061x[issn] or 1055-7903[issn] or 1060-1538[issn] or 1061-4036[issn] or 1064-7554[issn] or 1081-0706[issn] or 1090-5138[issn] or 1091-6490[issn] or 1095-9203[issn] or 1121-7138[issn] or 1176-9343[issn] or 1369-5274[issn] or 1369-8486[issn] or 1399-560x[issn] or 1433-8319[issn] or 1439-6092[issn] or 1462-2912[issn] or 1464-7931[issn] or 1466-5026[issn] or 1471-0056[issn] or 1471-2091[issn] or 1471-2105[issn] or 1471-2121[issn] or 1471-213x[issn] or 1471-2148[issn] or 1471-2156[issn] or 1471-2164[issn] or 1471-2180[issn] or 1471-2199[issn] or 1471-2229[issn] or 1471-4922[issn] or 1472-6785[issn] or 1474-7049[issn] or 1520-541x[issn] or 1522-0613[issn] or 1527-8204[issn] or 1543-5008[issn] or 1543-592x[issn] or 1552-4884[issn] or 1552-5007[issn] or 1661-5425[issn] or 1674-4918[issn] or 1740-1526[issn] or 1741-7007[issn] or 1752-0509[issn] or 1752-4571[issn] or 1753-6561[issn] or 1756-0500[issn] or 1758-2229[issn] or 1759-6653[issn] or 1933-5377[issn] or 1935-7877[issn] or 1936-6426[issn] or 1941-1405[issn] or 1943-0264[issn] or 1944-3277[issn] or 2036-2641[issn] or 2041-210x[issn] or 2045-7758[issn] or 2049-2618[issn] or 2050-6201[issn] or 2058-5276[issn] or 2090-8032[issn] or 2163-9434[issn] or 2165-3402[issn] or 2210-6502[issn] or 2296-701x[issn] or 2326-8298[issn] or 2329-9002[issn] or 2333-9683[issn] or 2397-334x[issn] or freeble ) NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-01-15

Wu X, Cabanos C, TA Rapoport (2018)

Structure of the post-translational protein translocation machinery of the ER membrane.

Nature pii:10.1038/s41586-018-0856-x [Epub ahead of print].

Many proteins must translocate through the protein-conducting Sec61 channel in the eukaryotic endoplasmic reticulum membrane or the SecY channel in the prokaryotic plasma membrane1,2. Proteins with hydrophobic signal sequences are first recognized by the signal recognition particle (SRP)3,4 and then moved co-translationally through the Sec61/SecY channel by the associated translating ribosome. Substrates with less hydrophobic signal sequences bypass SRP and are moved through the channel post-translationally5,6. In eukaryotic cells, post-translational translocation is mediated by the association of the Sec61 channel with another membrane protein complex, the Sec62/Sec63 complex7-9, and substrates are moved through the channel by the luminal BiP ATPase9. How the Sec62/63 complex activates the Sec61 channel for post-translational translocation is unclear. Here, we report the electron cryo-microscopy (cryo-EM) structure of the Sec complex from S. cerevisiae, consisting of the Sec61 channel and the Sec62, Sec63, Sec71, and Sec72 proteins. Sec63 causes wide opening of the lateral gate of the Sec61 channel, priming it for the passage of low-hydrophobicity signal sequences into the lipid phase, without displacing the channel's plug domain. Lateral channel opening is triggered by Sec63 interacting with both cytosolic loops in the C-terminal half of Sec61 and trans-membrane (TM) segments in the N-terminal half of the Sec61 channel. The cytosolic Brl domain of Sec63 blocks ribosome binding to the channel and recruits Sec71 and Sec72, positioning them for the capture of polypeptides associated with cytosolic Hsp70 (ref. 10). Our structure shows how the Sec61 channel is activated for post-translational protein translocation.

RevDate: 2019-01-09

Abdelaziz M, Bakkali M, Gómez JM, et al (2019)

Anther Rubbing, a New Mechanism That Actively Promotes Selfing in Plants.

The American naturalist, 193(1):140-147.

Self-fertilization has recurrently evolved in plants, involving different strategies and traits and often loss of attractive functions, collectively known as the selfing syndrome. However, few traits that actively promote self-fertilization have been described. Here we describe a novel mechanism promoting self-fertilization in the Brassicaceae species Erysimum incanum. This mechanism, which we called "anther rubbing," consists of autonomous, repeated, and coordinated movements of the stamens over the stigma during flower opening. We have documented anther rubbing by time-lapse videos and experimentally show that it causes self-pollen deposition on stigmas and is sufficient to achieve maximal reproductive output in E. incanum. We predict that these movements should occur in species with limited inbreeding depression, and indeed we find that inbreeding depression in seed production is negligible in this species. While many studies have documented complex floral traits that promote outcrossing, the occurrence of anther rubbing demonstrates that plants can evolve elaborate and underappreciated adaptations to promote self-fertilization.

RevDate: 2019-01-09

Backmann P, Grimm V, Jetschke G, et al (2019)

Delayed Chemical Defense: Timely Expulsion of Herbivores Can Reduce Competition with Neighboring Plants.

The American naturalist, 193(1):125-139.

Time delays in plant responses to insect herbivory are thought to be the principal disadvantage of induced over constitutive defenses, suggesting that there should be strong selection for rapid responses. However, observed time delays between the onset of herbivory and defense induction vary considerably among plants. We postulate that strong competition with conspecifics is an important codeterminant of the cost-benefit balance for induced responses. There may be a benefit to the plant to delay mounting a full defense response until the herbivore larvae are mobile enough to leave and large enough to cause severe damage to neighboring plants. Thus, delayed responses could reduce the competitive pressure on the focal plant. To explore this idea, we developed an individual-based model using data from wild tobacco, Nicotiana attenuata, and its specialized herbivore, Manduca sexta. Chemical defense was assumed to be costly in terms of reduced plant growth. We used a genetic algorithm with the plant's delay time as a heritable trait. A stationary distribution of delay times emerged, which under high herbivore densities peaked at higher values, which were related to the time larvae need to grow large enough to severely damage neighboring plants. Plants may thus tip the competitive balance by expelling insect herbivores to move to adjacent plants when the herbivores are most damaging. Thus, herbivores become part of a plant's strategy for reducing competition and increasing fitness.

RevDate: 2019-01-09

Wardlaw AM, AF Agrawal (2019)

Sexual Conflict and Sexually Transmitted Infections (STIs): Coevolution of Sexually Antagonistic Host Traits with an STI.

The American naturalist, 193(1):E1-E14.

In many taxa, there is a conflict between the sexes over mating rate. The outcome of sexually antagonistic coevolution depends on the costs of mating and natural selection against sexually antagonistic traits. A sexually transmitted infection (STI) changes the relative strength of these costs. We study the three-way evolutionary interaction among male persistence, female resistance, and STI virulence for two types of STIs: a viability-reducing STI and a reproduction-reducing STI. A viability-reducing STI escalates conflict between the sexes. This leads to increased STI virulence (i.e., full coevolution) if the costs of sexually antagonistic traits occur through viability but not through reproduction. In contrast, a reproduction-reducing STI de-escalates the sexual conflict, but STI virulence does not coevolve in response. We also investigated the establishment probability of STIs under different combinations of evolvability. Successful invasion by a viability-reducing STI becomes less likely if hosts (but not parasites) are evolvable, especially if only the female trait can evolve. A reproduction-reducing STI can almost always invade because it does not kill its host. We discuss how the evolution of host and parasite traits in a system with sexual conflict differs from a system with female mate choice.

RevDate: 2019-01-09

Ferrari M, Lindholm AK, B König (2019)

Fitness Consequences of Female Alternative Reproductive Tactics in House Mice (Mus musculus domesticus).

The American naturalist, 193(1):106-124.

Alternative reproductive tactics (ARTs) are defined as discrete differences in morphological, physiological, and/or behavioral traits associated with reproduction that occur within the same sex and population. House mice provide a rare example of ARTs in females, which can rear their young either solitarily or together with one or several other females in a communal nest. We assessed the fitness consequences of communal and solitary breeding in a wild population to understand how the two tactics can be evolutionarily stable. Females switched between the two tactics (with more than 50% of all females having two or more litters using both tactics), pointing toward communal and solitary breeding being two tactics within a single strategy and not two genetically determined strategies. Communal breeding resulted in reduced pup survival and negatively impacted female reproductive success. Older and likely heavier females more often reared their litters solitarily, indicating that females use a condition-dependent strategy. Solitary breeding seems the more successful tactic, and only younger and likely less competitive females might opt for communal nursing, even at the cost of increased pup mortality. This study emphasizes the importance of analyzing phenotypic plasticity and its role in cooperation in the context of female ARTs.

RevDate: 2019-01-09

Gouveia SF, Bovo RP, Rubalcaba JG, et al (2019)

Biophysical Modeling of Water Economy Can Explain Geographic Gradient of Body Size in Anurans.

The American naturalist, 193(1):51-58.

Geographical gradients of body size express climate-driven constraints on animals, but whether they exist and what causes them in ectotherms remains contentious. For amphibians, the water conservation hypothesis posits that larger bodies reduce evaporative water loss (EWL) along dehydrating gradients. To address this hypothesis mechanistically, we build on well-established biophysical equations of water exchange in anurans to propose a state-transition model that predicts an increase of either body size or resistance to EWL as alternative specialization along dehydrating gradients. The model predicts that species whose water economy is more sensitive to variation in body size than to variation in resistance to EWL should increase in size in response to increasing potential evapotranspiration (PET). To evaluate the model predictions, we combine physiological measurements of resistance to EWL with geographic data of body size for four different anuran species. Only one species, Dendropsophus minutus, was predicted to exhibit a positive body size-PET relationship. Results were as predicted for all cases, with one species-Boana faber-showing a negative relationship. Based on an empirically verified mathematical model, we show that clines of body size among anurans depend on the current values of those traits and emerge as an advantage for water conservation. Our model offers a mechanistic and compelling explanation for the cause and variation of gradients of body size in anurans.

RevDate: 2019-01-09

Anonymous (2019)

2018 American Society of Naturalists Awards.

The American naturalist, 193(1):ii-iii.

RevDate: 2019-01-09

Hahn PG, Agrawal AA, Sussman KI, et al (2019)

Population Variation, Environmental Gradients, and the Evolutionary Ecology of Plant Defense against Herbivory.

The American naturalist, 193(1):20-34.

A central tenet of plant defense theory is that adaptation to the abiotic environment sets the template for defense strategies, imposing a trade-off between plant growth and defense. Yet this trade-off, commonly found among species occupying divergent resource environments, may not occur across populations of single species. We hypothesized that more favorable climates and higher levels of herbivory would lead to increases in growth and defense across plant populations. We evaluated whether plant growth and defense traits covaried across 18 populations of showy milkweed (Asclepias speciosa) inhabiting an east-west climate gradient spanning 25° of longitude. A suite of traits impacting defense (e.g., latex, cardenolides), growth (e.g., size), or both (e.g., specific leaf area [SLA], trichomes) were measured in natural populations and in a common garden, allowing us to evaluate plastic and genetically based variation in these traits. In natural populations, herbivore pressure increased toward warmer sites with longer growing seasons. Growth and defense traits showed strong clinal patterns and were positively correlated. In a common garden, clines with climatic origin were recapitulated only for defense traits. Correlations between growth and defense traits were also weaker and more negative in the common garden than in the natural populations. Thus, our data suggest that climatically favorable sites likely facilitate the evolution of greater defense at minimal costs to growth, likely because of increased resource acquisition.

RevDate: 2019-01-09

Patin R, Fortin D, Sueur C, et al (2019)

Space Use and Leadership Modify Dilution Effects on Optimal Vigilance under Food-Safety Trade-Offs.

The American naturalist, 193(1):E15-E28.

Dilution of predation risk within groups allows individuals to be less vigilant and forage more while still facing lower risk than if they were alone. How group size influences vigilance when individuals can also adjust their space use and whether this relationship differs among individuals contributing differently to space use decisions remain unknown. We present a model-based study of how dilution affects the optimal antipredator behavior of group members in groups where all individuals determine their vigilance level while group leaders also determine space use. We showed that optimal vigilance did not always decrease with group size, as it was sometimes favorable for individuals in larger groups to use riskier patches while remaining vigilant. Followers were also generally less vigilant than leaders. Indeed, followers needed to acquire more resources than leaders, as only the latter could decide when to go to richer patches. Followers still benefit from dilution of predation risk compared with solitary individuals. For leaders, keeping their leadership status can be more important than incorporating new group members to increase dilution. We demonstrate that risk dilution impacts both optimal vigilance and space use, with fitness reward being tied to a member's ability to influence group space use.

RevDate: 2019-01-09

Webb MH, Heinsohn R, Sutherland WJ, et al (2019)

An Empirical and Mechanistic Explanation of Abundance-Occupancy Relationships for a Critically Endangered Nomadic Migrant.

The American naturalist, 193(1):59-69.

The positive abundance-occupancy relationship (AOR) is a pervasive pattern in macroecology. Similarly, the association between occupancy (or probability of occurrence) and abundance is also usually assumed to be positive and in most cases constant. Examples of AORs for nomadic species with variable distributions are extremely rare. Here we examined temporal and spatial trends in the AOR over 7 years for a critically endangered nomadic migrant that relies on dynamic pulses in food availability to breed. We predicted a negative temporal relationship, where local mean abundances increase when the number of occupied sites decreases, and a positive relationship between local abundances and the probability of occurrence. We also predicted that these patterns are largely attributable to spatiotemporal variation in food abundance. The temporal AOR was significantly negative, and annual food availability was significantly positively correlated with the number of occupied sites but negatively correlated with abundance. Thus, as food availability decreased, local densities of birds increased, and vice versa. The abundance-probability of occurrence relationship was positive and nonlinear but varied between years due to differing degrees of spatial aggregation caused by changing food availability. Importantly, high abundance (or occupancy) did not necessarily equate to high-quality habitat and may be indicative of resource bottlenecks or exposure to other processes affecting vital rates. Our results provide a rare empirical example that highlights the complexity of AORs for species that target aggregated food resources in dynamic environments.

RevDate: 2019-01-09

Leimar O, Dall SRX, McNamara JM, et al (2019)

Ecological Genetic Conflict: Genetic Architecture Can Shift the Balance between Local Adaptation and Plasticity.

The American naturalist, 193(1):70-80.

Genetic polymorphism can contribute to local adaptation in heterogeneous habitats, for instance, as a single locus with alleles adapted to different habitats. Phenotypic plasticity can also contribute to trait variation across habitats, through developmental responses to habitat-specific cues. We show that the genetic architecture of genetically polymorphic and plasticity loci may influence the balance between local adaptation and phenotypic plasticity. These effects of genetic architecture are instances of ecological genetic conflict. A reduced effective migration rate for genes tightly linked to a genetic polymorphism provides an explanation for the effects, and they can occur both for a single trait and for a syndrome of coadapted traits. Using individual-based simulations and numerical analysis, we investigate how among-habitat genetic polymorphism and phenotypic plasticity depend on genetic architecture. We also study the evolution of genetic architecture itself, in the form of rates of recombination between genetically polymorphic loci and plasticity loci. Our main result is that for plasticity genes that are unlinked to loci with between-habitat genetic polymorphism, the slope of a reaction norm is steeper in comparison with the slope favored by plasticity genes that are tightly linked to genes for local adaptation.

RevDate: 2019-01-09

Yeh DJ (2019)

Assortative Mating by an Obliquely Transmitted Local Cultural Trait Promotes Genetic Divergence: A Model.

The American naturalist, 193(1):81-92.

The effect of learned culture (e.g., birdsong dialects and human languages) on genetic divergence is unclear. Previous theoretical research suggests that because oblique learning allows phenotype transmission from individuals with no offspring to an unrelated individual in the next generation, the effect of sexual selection on the learned trait is masked. However, I propose that migration and spatially constrained learning can form statistical associations between cultural and genetic traits, which may allow selection on the cultural traits to indirectly affect the genetic traits. Here, I build a population genetic model that allows such statistical associations to form and find that sexual selection and divergent selection on the cultural trait can indeed help maintain genetic divergence through such statistical associations, while selection against genetic hybrids does not affect cultural trait divergence. Furthermore, I find that even when the cultural trait changes over time due to drift and mutation, it can still help maintain genetic divergence. These results suggest the role of obliquely transmitted traits in evolution may be underrated, and the lack of one-to-one associations between cultural and genetic traits may not be sufficient to disprove the role of culture in genetic divergence.

RevDate: 2019-01-09

Connallon T, Sharma S, C Olito (2019)

Evolutionary Consequences of Sex-Specific Selection in Variable Environments: Four Simple Models Reveal Diverse Evolutionary Outcomes.

The American naturalist, 193(1):93-105.

The evolutionary trajectories of species with separate sexes depend on the effects of genetic variation on female and male traits as well as the direction and alignment of selection between the sexes. Classical theory has shown that evolution is equally responsive to selection on females and males, with natural selection increasing the product of the average relative fitness of each sex over time. This simple rule underlies several important predictions regarding the maintenance of genetic variation, the genetic basis of adaptation, and the dynamics of "sexually antagonistic" alleles. Nevertheless, theories of sex-specific selection overwhelmingly focus on evolution in constant environments, and it remains unclear whether they apply under changing conditions. We derived four simple models of sex-specific selection in variable environments and explored how conditions of population subdivision, the timing of dispersal, sex differences in dispersal, and the nature of environmental change mediate the evolutionary dynamics of sex-specific adaptation. We find that these dynamics are acutely sensitive to ecological, demographic, and life-history attributes that vary widely among species, with classical predictions breaking down in contexts of environmental heterogeneity. The evolutionary rules governing sex-specific adaptation may therefore differ between species, suggesting new avenues for research on the evolution of sexual dimorphism.

RevDate: 2019-01-09

Stuart YE (2019)

Divergent Uses of "Parallel Evolution" during the History of The American Naturalist.

The American naturalist, 193(1):11-19.

The mechanistic link between natural selection and parallel evolution is well established. Natural selection is the only known deterministic process that can regularly overcome chance and historical contingency to generate the evolution of similar characteristics in independent populations inhabiting similar environments. However, the ready inference of natural selection from parallel evolution has been established only relatively recently. Here, I review the use of "parallel evolution" in the first 125 years of The American Naturalist and show that there were other well-accepted definitions of the term through the history of the field. I discuss the legacy of those alternative ideas and how they helped to shape evolution and ecology as we know them today and finish by discussing a geometric use for "parallel" that may reduce terminological confusion.

RevDate: 2019-01-09

Shaw RG (2019)

From the Past to the Future: Considering the Value and Limits of Evolutionary Prediction.

The American naturalist, 193(1):1-10.

The complex interplay of the multiple genetic processes of evolution and the ecological contexts in which they proceed frustrates detailed identification of many of the states of populations, both past and future, that may be of interest. Prediction of rates of adaptation, in the sense of change in mean fitness, into the future would, however, valuably inform expectations for persistence of populations, especially in our era of rapid environmental change. Heavy investment in genomics and other molecular tools has fueled belief that those approaches can effectively predict adaptation into the future. I contest this view. Genome scans display the genomic footprints of the effects of natural selection and the other evolutionary processes over past generations, but it remains problematic to predict future change in mean fitness via genomic approaches. Here, I advocate for a direct approach to prediction of rates of ongoing adaptation. Following an overview of relevant quantitative genetic approaches, I outline the promise of the fundamental theorem of natural selection for the study of the adaptive process. Empirical implementation of this concept can productively guide efforts both to deepen scientific insight into the process of adaptation and to inform measures for conserving the biota in the face of rapid environmental change.

RevDate: 2019-01-09

López ME, Benestan L, Moore JS, et al (2019)

Comparing genomic signatures of domestication in two Atlantic salmon (Salmo salar L.) populations with different geographical origins.

Evolutionary applications, 12(1):137-156 pii:EVA12689.

Selective breeding and genetic improvement have left detectable signatures on the genomes of domestic species. The elucidation of such signatures is fundamental for detecting genomic regions of biological relevance to domestication and improving management practices. In aquaculture, domestication was carried out independently in different locations worldwide, which provides opportunities to study the parallel effects of domestication on the genome of individuals that have been selected for similar traits. In this study, we aimed to detect potential genomic signatures of domestication in two independent pairs of wild/domesticated Atlantic salmon populations of Canadian and Scottish origins, respectively. Putative genomic regions under divergent selection were investigated using a 200K SNP array by combining three different statistical methods based either on allele frequencies (LFMM, Bayescan) or haplotype differentiation (Rsb). We identified 337 and 270 SNPs potentially under divergent selection in wild and hatchery populations of Canadian and Scottish origins, respectively. We observed little overlap between results obtained from different statistical methods, highlighting the need to test complementary approaches for detecting a broad range of genomic footprints of selection. The vast majority of the outliers detected were population-specific but we found four candidate genes that were shared between the populations. We propose that these candidate genes may play a role in the parallel process of domestication. Overall, our results suggest that genetic drift may have override the effect of artificial selection and/or point toward a different genetic basis underlying the expression of similar traits in different domesticated strains. Finally, it is likely that domestication may predominantly target polygenic traits (e.g., growth) such that its genomic impact might be more difficult to detect with methods assuming selective sweeps.

RevDate: 2019-01-09

Pitt D, Sevane N, Nicolazzi EL, et al (2019)

Domestication of cattle: Two or three events?.

Evolutionary applications, 12(1):123-136 pii:EVA12674.

Cattle have been invaluable for the transition of human society from nomadic hunter-gatherers to sedentary farming communities throughout much of Europe, Asia and Africa since the earliest domestication of cattle more than 10,000 years ago. Although current understanding of relationships among ancestral populations remains limited, domestication of cattle is thought to have occurred on two or three occasions, giving rise to the taurine (Bos taurus) and indicine (Bos indicus) species that share the aurochs (Bos primigenius) as common ancestor ~250,000 years ago. Indicine and taurine cattle were domesticated in the Indus Valley and Fertile Crescent, respectively; however, an additional domestication event for taurine in the Western Desert of Egypt has also been proposed. We analysed medium density Illumina Bovine SNP array (~54,000 loci) data across 3,196 individuals, representing 180 taurine and indicine populations to investigate population structure within and between populations, and domestication and demographic dynamics using approximate Bayesian computation (ABC). Comparative analyses between scenarios modelling two and three domestication events consistently favour a model with only two episodes and suggest that the additional genetic variation component usually detected in African taurine cattle may be explained by hybridization with local aurochs in Africa after the domestication of taurine cattle in the Fertile Crescent. African indicine cattle exhibit high levels of shared genetic variation with Asian indicine cattle due to their recent divergence and with African taurine cattle through relatively recent gene flow. Scenarios with unidirectional or bidirectional migratory events between European taurine and Asian indicine cattle are also plausible, although further studies are needed to disentangle the complex human-mediated dispersion patterns of domestic cattle. This study therefore helps to clarify the effect of past demographic history on the genetic variation of modern cattle, providing a basis for further analyses exploring alternative migratory routes for early domestic populations.

RevDate: 2019-01-09

Pitt D, Bruford MW, Barbato M, et al (2019)

Demography and rapid local adaptation shape Creole cattle genome diversity in the tropics.

Evolutionary applications, 12(1):105-122 pii:EVA12641.

The introduction of Iberian cattle in the Americas after Columbus' arrival imposed high selection pressures on a limited number of animals over a brief period of time. Knowledge of the genomic regions selected during this process may help in enhancing climatic resilience and sustainable animal production. We first determined taurine and indicine contributions to the genomic structure of modern Creole cattle. Second, we inferred their demographic history using approximate Bayesian computation (ABC), linkage disequilibrium (LD) and Ne Slope (NeS) analysis. Third, we performed whole genome scans for selection signatures based on cross-population extended haplotype homozygosity (XP-EHH) and population differentiation (FST) to disentangle the genetic mechanisms involved in adaptation and phenotypic change by a rapid and major environmental transition. To tackle these questions, we combined SNP array data (~54,000 SNPs) in Creole breeds with their modern putative Iberian ancestors. Reconstruction of the population history of Creoles from the end of the 15th century indicated a major demographic expansion until the introduction of zebu and commercial breeds into the Americas ~180 years ago, coinciding with a drastic Ne contraction. NeS analysis provided insights into short-term complexity in population change and depicted a decrease/expansion episode at the end of the ABC-inferred expansion, as well as several additional fluctuations in Ne with the attainment of the current small Ne only towards the end of the 20th century. Selection signatures for tropical adaptation pinpointed the thermoregulatory slick hair coat region, identifying a new candidate gene (GDNF), as well as novel candidate regions involved in immune function, behavioural processes, iron metabolism and adaptation to new feeding conditions. The outcomes from this study will help in future-proofing farm animal genetic resources (FAnGR) by providing molecular tools that allow selection for improved cattle performance, resilience and welfare under climate change.

RevDate: 2019-01-09

Vigueira CC, Qi X, Song BK, et al (2019)

Call of the wild rice: Oryza rufipogon shapes weedy rice evolution in Southeast Asia.

Evolutionary applications, 12(1):93-104 pii:EVA12581.

Agricultural weeds serve as productive models for studying the genetic basis of rapid adaptation, with weed-adaptive traits potentially evolving multiple times independently in geographically distinct but environmentally similar agroecosystems. Weedy relatives of domesticated crops can be especially interesting systems because of the potential for weed-adaptive alleles to originate through multiple mechanisms, including introgression from cultivated and/or wild relatives, standing genetic variation, and de novo mutations. Weedy rice populations have evolved multiple times through dedomestication from cultivated rice. Much of the genomic work to date in weedy rice has focused on populations that exist outside the range of the wild crop progenitor. In this study, we use genome-wide SNPs generated through genotyping-by-sequencing to compare the evolution of weedy rice in regions outside the range of wild rice (North America, South Korea) and populations in Southeast Asia, where wild rice populations are present. We find evidence for adaptive introgression of wild rice alleles into weedy rice populations in Southeast Asia, with the relative contributions of wild and cultivated rice alleles varying across the genome. In addition, gene regions underlying several weed-adaptive traits are dominated by genomic contributions from wild rice. Genome-wide nucleotide diversity is also much higher in Southeast Asian weeds than in North American and South Korean weeds. Besides reflecting introgression from wild rice, this difference in diversity likely reflects genetic contributions from diverse cultivated landraces that may have served as the progenitors of these weedy populations. These important differences in weedy rice evolution in regions with and without wild rice could inform region-specific management strategies for weed control.

RevDate: 2019-01-09

Taitano N, Bernau V, Jardón-Barbolla L, et al (2019)

Genome-wide genotyping of a novel Mexican Chile Pepper collection illuminates the history of landrace differentiation after Capsicum annuum L. domestication.

Evolutionary applications, 12(1):78-92 pii:EVA12651.

Studies of genetic diversity among phenotypically distinct crop landraces improve our understanding of fruit evolution and genome structure under domestication. Chile peppers (Capsicum spp. L.) are economically valuable and culturally important species, and extensive phenotypic variation among landraces exists in southern Mexico, a center of C. annuum diversity. We collected 103 chile pepper seed accessions from 22 named landraces across 27 locations in southern Mexico. We genotyped these accessions with genotyping by sequencing (GBS), yielding 32,623 filtered single-nucleotide polymorphisms. Afterward, we genotyped 32 additional C. annuum accessions from a global collection for comparison to the Mexican collection. Within the Mexican collection, genetic assignment analyses showed clear genetic differentiation between landraces and clarified the unique nature of the Tusta landrace. Further clustering analyses indicated that the largest fresh-use Chile de Agua and dry-use Costeño landraces were part of separate clades, indicating that these two landraces likely represent distinct populations. The global accessions showed considerable admixture and limited clustering, which may be due to the collapse of use-type divisions outside of Central America. The separation of the Mexican landraces in part by fruit morphology related to use highlights the relevance of this use-type morphological diversity for plant breeders and the utility of fruit development variation for evolutionary biologists.

RevDate: 2019-01-09

Schreiber M, Himmelbach A, Börner A, et al (2019)

Genetic diversity and relationship between domesticated rye and its wild relatives as revealed through genotyping-by-sequencing.

Evolutionary applications, 12(1):66-77 pii:EVA12624.

Rye (Secale cereale L.) is a cereal grass that is an important food crop in Central and Eastern Europe. In contrast to its close relatives wheat and barley, it was not a founder crop of Neolithic agriculture, but is considered a secondary domesticate that may have become a crop plant only after a transitory phase as a weed. As a minor crop of only local importance, genomic resources in rye are underdeveloped, and few population genetic studies using genomewide markers have been published to date. We collected genotyping-by-sequencing data for 603 individuals from 101 genebank accessions of domesticated rye and its wild progenitor S. cereale subsp. vavilovii and related species in the genus Secale. Variant detection in the context of a recently published draft sequence assembly of cultivated rye yielded 55,744 single nucleotide polymorphisms with present genotype calls in 90% of samples. Analysis of population structure recapitulated the taxonomy of the genus Secale. We found only weak genetic differentiation between wild and domesticated rye with likely gene flow between the two groups. Moreover, incomplete lineage sorting was frequent between Secale species because of either ongoing gene flow or recent speciation. Our study highlights the necessity of gauging the representativeness of ex situ germplasm collections for domestication studies and motivates a more in-depth analysis of the interplay between sequence divergence and reproductive isolation in the genus Secale.

RevDate: 2019-01-09

Owens GL, Baute GJ, Hubner S, et al (2019)

Genomic sequence and copy number evolution during hybrid crop development in sunflowers.

Evolutionary applications, 12(1):54-65 pii:EVA12603.

Hybrid crops, an important part of modern agriculture, rely on the development of male and female heterotic gene pools. In sunflowers, heterotic gene pools were developed through the use of crop-wild relatives to produce cytoplasmic male sterile female and branching, fertility restoring male lines. Here, we use genomic data from a diversity panel of male, female, and open-pollinated lines to explore the genetic changes brought during modern improvement. We find the male lines have diverged most from their open-pollinated progenitors and that genetic differentiation is concentrated in chromosomes, 8, 10 and 13, due to introgressions from wild relatives. Ancestral variation from open-pollinated varieties almost universally evolved in parallel for both male and female lines suggesting little or no selection for heterotic overdominance. Furthermore, we show that gene content differs between the male and female lines and that differentiation in gene content is concentrated in high FST regions. This means that the introgressions that brought branching and fertility restoration to the male lines, brought with them different gene content from the ancestral haplotypes, including the removal of some genes. Although we find no evidence that gene complementation genomewide is responsible for heterosis between male and female lines, several of the genes that are largely absent in either the male or female lines are associated with pathogen defense, suggesting complementation may be functionally relevant for crop breeders.

RevDate: 2019-01-09

Wales N, Akman M, Watson RHB, et al (2019)

Ancient DNA reveals the timing and persistence of organellar genetic bottlenecks over 3,000 years of sunflower domestication and improvement.

Evolutionary applications, 12(1):38-53 pii:EVA12594.

Here, we report a comprehensive paleogenomic study of archaeological and ethnographic sunflower remains that provides significant new insights into the process of domestication of this important crop. DNA from both ancient and historic contexts yielded high proportions of endogenous DNA, and although archaeological DNA was found to be highly degraded, it still provided sufficient coverage to analyze genetic changes over time. Shotgun sequencing data from specimens from the Eden's Bluff archaeological site in Arkansas yielded organellar DNA sequence from specimens up to 3,100 years old. Their sequences match those of modern cultivated sunflowers and are consistent with an early domestication bottleneck in this species. Our findings also suggest that recent breeding of sunflowers has led to a loss of genetic diversity that was present only a century ago in Native American landraces. These breeding episodes also left a profound signature on the mitochondrial and plastid haplotypes in cultivars, as two types were intentionally introduced from other Helianthus species for crop improvement. These findings gained from ancient and historic sunflower specimens underscore how future in-depth gene-based analyses can advance our understanding of the pace and targets of selection during the domestication of sunflower and other crop species.

RevDate: 2019-01-09

Allaby RG, Ware RL, L Kistler (2019)

A re-evaluation of the domestication bottleneck from archaeogenomic evidence.

Evolutionary applications, 12(1):29-37 pii:EVA12680.

Domesticated crops show a reduced level of diversity that is commonly attributed to the "domestication bottleneck"; a drastic reduction in the population size associated with subsampling the wild progenitor species and the imposition of selection pressures associated with the domestication syndrome. A prediction of the domestication bottleneck is a sharp decline in genetic diversity early in the domestication process. Surprisingly, archaeological genomes of three major annual crops do not indicate that such a drop in diversity occurred early in the domestication process. In light of this observation, we revisit the general assumption of the domestication bottleneck concept in our current understanding of the evolutionary process of domestication.

RevDate: 2019-01-08

Schenkel MA, Pen I, Beukeboom LW, et al (2018)

Making sense of intralocus and interlocus sexual conflict.

Ecology and evolution, 8(24):13035-13050 pii:ECE34629.

Sexual conflict occurs because males and females are exposed to different selection pressures. This can affect many aspects of female and male biology, such as physiology, behavior, genetics, and even population ecology. Its broad impact has caused widespread interest in sexual conflict. However, a key aspect of sexual conflict is often confused; it comprises two distinct forms: intralocus and interlocus sexual conflict (IASC and IRSC). Although both are caused by sex differences in selection, they operate via different proximate and ultimate mechanisms. Intralocus sexual conflict and IRSC are often not clearly defined as separate processes in the scientific literature, which impedes a proper understanding of each form as well as of their relative impact on sexual conflict. Furthermore, our current knowledge of the genetics of these phenomena is severely limited. This prevents us from empirically testing numerous theories regarding the role of these two forms of sexual conflict in evolution. Here, we clarify the distinction between IASC and IRSC, by discussing how male and female interests differ, how and when sex-specific adaptation occurs, and how this may lead to evolutionary change. We then describe a framework for their study, focusing on how future experiments may help identify the genetics underlying these phenomena. Through this, we hope to promote a more critical reflection on IASC and IRSC as well as underline the necessity of genetic and mechanistic studies of these two phenomena.

RevDate: 2019-01-08

Ottenburghs J (2018)

Exploring the hybrid speciation continuum in birds.

Ecology and evolution, 8(24):13027-13034 pii:ECE34558.

Hybridization is increasingly recognized as a creative evolutionary force contributing to adaptation and speciation. Homoploid hybrid speciation-the process in which hybridization results in a stable, fertile, and reproductively isolated hybrid lineage where there is no change in ploidy-has been documented in several taxa. Hybridization can directly contribute to reproductive isolation or reinforce it at a later stage. Alternatively, hybridization might not be related to the evolution of reproductive isolation. To account for these different scenarios, I propose to discriminate between two types of hybrid speciation: type I where reproductive isolation is a direct consequence of hybridization and type II where it is the by-product of other processes. I illustrate the applicability of this classification scheme with avian examples. To my knowledge, seven hybrid bird species have been proposed: Italian sparrow, Audubon's warbler, Genovesa mockingbird, Hawaiian duck, red-breasted goose, golden-crowned manakin, and a recent lineage of Darwin's finches on the island of Daphne Major ("Big Bird"). All studies provide convincing evidence for hybridization, but do not always confidently discriminate between scenarios of hybrid speciation and recurrent introgressive hybridization. The build-up of reproductive isolation between the hybrid species and their parental taxa is mainly driven by premating isolation mechanisms and comparable to classical speciation events. One hybrid species can be classified as type I ("Big Bird") while three species constitute type II hybrid species (Italian sparrow, Audubon's warbler, and golden-crowned manakin). The diversity in hybrid bird species across a range of divergence times also provides an excellent opportunity to study the evolution of hybrid genomes in terms of genome stabilization and adaptation.

RevDate: 2019-01-08

Hou Z, Wang Z, Ye Z, et al (2018)

Phylogeographic analyses of a widely distributed Populus davidiana: Further evidence for the existence of glacial refugia of cool-temperate deciduous trees in northern East Asia.

Ecology and evolution, 8(24):13014-13026 pii:ECE34755.

Despite several phylogeographic studies had provided evidence to support the existence of glacial refugia of cool-temperate deciduous trees in northeast China, the species used in these studies were limited by the species ranges, which could not exclude the possibility that northern populations were the colonists from southern refugial populations during the last glacial maximum (LGM). Here, we estimated the nucleotide variation in Populus davidiana, a widespread species distributed in Eurasia. Three groups in northeast, central, and southwest China were constructed according to the simulation results from SAMOVA, composition of chloroplast haplotypes and structure results. We revealed that the northeast China had endemic haplotypes, the haplotypes and nucleotide diversity in northern regions were not lower than that in southern China, and this species has not experienced population expansion base on the estimation of Bayesian skyline plots. Ecological niche modeling (ENM) indicated that the northeast China had a high suitability score during the last glacial maximum. The combined evidence clearly demonstrated that northeastern and southwestern refugia were maintained across the current distributional range of P. davidiana during the LGM. The genetic differentiation between these two refugia might be mainly caused by differences of climate among these areas. The phylogeographic analyses of a widely distributed P. davidiana provided robust evidence to clarify the issue of refugia in northeast China, and these results are of great importance for understanding the influence of Quaternary glaciations on the distribution and evolution of species in East Asia.

RevDate: 2019-01-08

Li S, Liu D, Zhang R, et al (2018)

Effects of a presumably protective endosymbiont on life-history characters and their plasticity for its host aphid on three plants.

Ecology and evolution, 8(24):13004-13013 pii:ECE34754.

Hamiltonella defensa is well known for its protective roles against parasitoids for its aphid hosts, but its functional roles in insect-plant interactions are less understood. Thus, the impact of H. defensa infections on life-history characters and the underlying genetic variation for the grain aphid, Sitobion avenae (Fabricius), was explored on three plants (i.e., wheat, oat, and rye). Compared to cured lines, H. defensa infected lines of S. avenae had lower fecundity on wheat and oat, but not on rye, suggesting an infection cost for the aphid on susceptible host plants. However, when tested on rye, the infected lines showed a shorter developmental time for the nymphal stage than corresponding cured lines, showing some benefit for S. avenae carrying the endosymbiont on resistant host plants. The infection of H. defensa altered genetic variation underlying its host S. avenea's life-history characters, which was shown by differences in heritabilities and genetic correlations of life-history characters between S. avenae lines infected and cured of the endosymbiont. This was further substantiated by disparity in G-matrices of their life-history characters for the two types of aphid lines. The G-matrices for life-history characters of aphid lines infected with and cured of H. defensa were significantly different from each other on rye, but not on oat, suggesting strong plant-dependent effects. The developmental durations of infected S. avenae lines showed a lower plasticity compared with those of corresponding cured lines, and this could mean higher adaptability for the infected lines.Overall, our results showed novel functional roles of a common secondary endosymbiont (i.e., H. defensa) in plant-insect interactions, and its infections could have significant consequences for the evolutionary ecology of its host insect populations in nature.

RevDate: 2019-01-08

MacLaren AR, Crump PS, Royle JA, et al (2018)

Observer-free experimental evaluation of habitat and distance effects on the detection of anuran and bird vocalizations.

Ecology and evolution, 8(24):12991-13003 pii:ECE34752.

Acoustic surveys of vocalizing animals are conducted to determine density, distribution, and diversity. Acoustic surveys are traditionally performed by human listeners, but automated recording devices (ARD) are becoming increasingly popular. Signal strength decays, or attenuates, with increasing distance between source and receiver and some habitat types may differentially increase attenuation beyond the effects of distance alone. These combined effects are rarely accounted for in acoustic monitoring programs. We evaluated the performance of three playback devices and three ARD models using the calls of six anurans, six birds, and four pure tones. Based on these evaluations, we determined the optimal playback and recording devices. Using these optimal devices, we broadcast and recorded vocalizations in five habitat types along 1,000 m transects. We used generalized linear models to test for effects of habitat, distance, species, environmental, and landscape variables. We predicted detection probabilities for each vocalization, in each habitat type, from 0 to 1,000 m. Among playback devices, only a remote predator caller simulated vocalizations consistently. Differences of ~10 dB were observed among ARDs. For all species, we found differences in detectability between open and closed canopy habitats. We observed large differences in predicted detection probability among species in each habitat type, as well as along 1,000 m transects. Increases in temperature, barometric pressure, and wind speed significantly decreased detection probability. However, aside from differences among species, habitat, and distance, topography impeding a line-of-sight between sound source and receiver had the greatest negative influence on detections. Our results suggest researchers should model the effects of habitat, distance, and frequency on detection probability when performing acoustic surveys. To optimize survey design, we recommend pilot measurements among varying habitats.

RevDate: 2019-01-08

Ida TY, Takanashi K, Tamura M, et al (2018)

Defensive chemicals of neighboring plants limit visits of herbivorous insects: Associational resistance within a plant population.

Ecology and evolution, 8(24):12981-12990 pii:ECE34750.

Despite our understanding of chemical defenses and their consequences for plant performance and herbivores, we know little about whether defensive chemicals in plant tissues, such as alkaloids, and their spatial variation within a population play unappreciated and critical roles in plant-herbivore interactions. Neighboring plants can decrease or increase attractiveness of a plant to herbivores, an example of a neighborhood effect. Chemical defensive traits may contribute to neighborhood effects in plant-herbivore interactions. We examined the effects of nicotine in leaves (a non-emitted defense chemical) on plant-herbivore interactions in a spatial context, using two varieties of Nicotiana tabacum with different nicotine levels. A common garden experiment demonstrated that visits by grasshoppers decreased with increasing density of neighboring plants with a greater nicotine level. In contrast, visits of leaf caterpillars were not affected by neighbors, irrespective of nicotine levels. Thus, our results clearly highlighted that the neighborhood effect caused by the nicotine in leaves depended on the insect identity, and it was mediated by plant-herbivore interactions, rather than plant-plant interactions. This study demonstrates that understanding of effects of plant defensive traits on plant-herbivore interactions requires careful consideration of the spatial distribution of plant defenses, and provides support for the importance of spatial context to accurately capture the ecological and evolutionary consequences of plant-herbivore interactions.

RevDate: 2019-01-08

Schell CJ, Young JK, Lonsdorf EV, et al (2018)

Parental habituation to human disturbance over time reduces fear of humans in coyote offspring.

Ecology and evolution, 8(24):12965-12980 pii:ECE34741.

A fundamental tenet of maternal effects assumes that maternal variance over time should have discordant consequences for offspring traits across litters. Yet, seldom are parents observed across multiple reproductive bouts, with few studies considering anthropogenic disturbances as an ecological driver of maternal effects. We observed captive coyote (Canis latrans) pairs over two successive litters to determine whether among-litter differences in behavior (i.e., risk-taking) and hormones (i.e., cortisol and testosterone) corresponded with parental plasticity in habituation. Thus, we explicitly test the hypothesis that accumulating experiences of anthropogenic disturbance reduces parental fear across reproductive bouts, which should have disparate phenotypic consequences for first- and second-litter offspring. To quantify risk-taking behavior, we used foraging assays from 5-15 weeks of age with a human observer present as a proxy for human disturbance. At 5, 10, and 15 weeks of age, we collected shaved hair to quantify pup hormone levels. We then used a quantitative genetic approach to estimate heritability, repeatability, and between-trait correlations. We found that parents were riskier (i.e., foraged more frequently) with their second versus first litters, supporting our prediction that parents become increasingly habituated over time. Second-litter pups were also less risk-averse than their first-litter siblings. Heritability for all traits did not differ from zero (0.001-0.018); however, we found moderate support for repeatability in all observed traits (r = 0.085-0.421). Lastly, we found evidence of positive phenotypic and cohort correlations among pup traits, implying that cohort identity (i.e., common environment) contributes to the development of phenotypic syndromes in coyote pups. Our results suggest that parental habituation may be an ecological cue for offspring to reduce their fear response, thus emphasizing the role of parental plasticity in shaping their pups' behavioral and hormonal responses toward humans.

RevDate: 2019-01-08

Fronhofer EA, Liebig J, Mitesser O, et al (2018)

Eusociality outcompetes egalitarian and solitary strategies when resources are limited and reproduction is costly.

Ecology and evolution, 8(24):12953-12964 pii:ECE34737.

Explaining the evolution and maintenance of animal groups remains a challenge. Surprisingly, fundamental ecological factors, such as resource variance and competition for limited resources, tend to be ignored in models of cooperation. We use a mathematical model previously developed to quantify the influence of different group sizes on resource use efficiency in egalitarian groups and extend its scope to groups with severe reproductive skew (eusocial groups). Accounting for resource limitation, the model allows calculation of optimal group sizes (highest resource use efficiency) and equilibrium population sizes in egalitarian as well as eusocial groups for a broad spectrum of environmental conditions (variance of resource supply). We show that, in contrast to egalitarian groups, eusocial groups may not only reduce variance in resource supply for survival, thus reducing the risk of starvation, they may also increase variance in resource supply for reproduction. The latter effect allows reproduction even in situations when resources are scarce. These two facets of eusocial groups, resource sharing for survival and resource pooling for reproduction, constitute two beneficial mechanisms of group formation. In a majority of environmental situations, these two benefits of eusociality increase resource use efficiency and lead to supersaturation-a strong increase in carrying capacity. The increase in resource use efficiency provides indirect benefits to group members even for low intra-group relatedness and may represent one potential explanation for the evolution and especially the maintenance of eusociality and cooperative breeding.

RevDate: 2019-01-08

Baecher JA, SC Richter (2018)

Environmental gradients in old-growth Appalachian forest predict fine-scale distribution, co-occurrence, and density of woodland salamanders.

Ecology and evolution, 8(24):12940-12952 pii:ECE34736.

Woodland salamanders are among the most abundant vertebrate animals in temperate deciduous forests of eastern North America. Because of their abundance, woodland salamanders are responsible for the transformation of nutrients and translocation of energy between highly disparate levels of trophic organization: detrital food webs and high-order predators. However, the spatial extent of woodland salamanders' role in the ecosystem is likely contingent upon the distribution of their biomass throughout the forest. We sought to determine if natural environmental gradients influence the fine-scale distribution and density of Southern Ravine Salamanders (Plethodon richmondi) and Cumberland Plateau Salamanders (P. kentucki). We addressed this objective by constructing occupancy, co-occurrence, and abundance models from temporally replicated surveys within an old-growth forest in the Cumberland Plateau region of Kentucky. We found that Plethodon richmondi had a more restricted fine-scale distribution than P. kentucki (mean occupancy probability [ ψ ¯ ^ ] = 0.737) and exhibited variable density, from <250 to >1000 individuals per hectare, associated with increased soil moisture and reduced solar exposure due to slope face. While more ubiquitously distributed (ψ ¯ ^ = 0.95), P. kentucki density varied from <400 to >1,000 individuals per hectare and was inversely related to increased solar exposure from canopy disturbance and landscape convexity. Our data suggest co-occurrence patterns of P. richmondi and P. kentucki are influenced primarily by abiotic conditions within the forest, and that populations likely occur independently and without evidence of biotic interaction. Given the critical role that woodland salamanders play in the maintenance of forest health, regions that support large populations of woodland salamanders, such as those highlighted in this study-mesic forest stands on north-to-east facing slopes with dense canopy and abundant natural cover, may provide enhanced ecosystem services and support the stability of the total forest.

RevDate: 2019-01-08

Sherratt E, Anstis M, JS Keogh (2018)

Ecomorphological diversity of Australian tadpoles.

Ecology and evolution, 8(24):12929-12939 pii:ECE34733.

Ecomorphology is the association between an organism's morphology and its ecology. Larval anuran amphibians (tadpoles) are classified into distinct ecomorphological guilds based upon morphological features and observations of their ecology. The extent to which guilds comprise distinct morphologies resulting from convergent evolution, the degree of morphological variability within each guild, and the degree of continuity in shape between guilds has not previously been examined in a phylogenetically informed statistical framework. Here, we examine tadpole ecomorphological guilds at a macroevolutionary scale by examining morphological diversity across the Australian continent. We use ecological data to classify species to guilds, and geometric morphometrics to quantify body shape in the tadpoles of 188 species, 77% of Australian frog diversity. We find that the ecomorphological guilds represented by Australian species are morphologically distinct, but there is substantial morphological variation associated with each guild, and all guilds together form a morphological continuum. However, in a phylogenetic comparative context, there is no significant difference in body shape among guilds. We also relate the morphological diversity of the Australian assemblage of tadpoles to a global sample and demonstrate that ecomorphological diversity of Australian tadpoles is limited with respect to worldwide species. Our results demonstrate that general patterns of ecomorphological variation are upheld in Australian tadpoles, but tadpole body shape is more variable and possibly generalist than generally appreciated.

RevDate: 2019-01-08

Sambhu H, Nankishore A, Turton SM, et al (2018)

Trade-offs for butterfly alpha and beta diversity in human-modified landscapes and tropical rainforests.

Ecology and evolution, 8(24):12918-12928 pii:ECE34732.

The accelerating expansion of human populations and associated economic activity across the globe have made maintaining large, intact natural areas increasingly challenging. The difficulty of preserving large intact landscapes in the presence of growing human populations has led to a growing emphasis on landscape approaches to biodiversity conservation with a complementary strategy focused on improving conservation in human-modified landscapes. This, in turn, is leading to intense debate about the effectiveness of biodiversity conservation in human-modified landscapes and approaches to better support biodiversity in those landscapes. Here, we compared butterfly abundance, alpha richness, and beta diversity in human-modified landscapes (urban, sugarcane) and natural, forested areas to assess the conservation value of human-modified landscapes within the Wet Tropics bioregion of Australia. We used fruit-baited traps to sample butterflies and analyzed abundance and species richness in respective land uses over a one-year period. We also evaluated turnover and spatial variance components of beta diversity to determine the extent of change in temporal and spatial variation in community composition. Forests supported the largest numbers of butterflies, but were lowest in each, alpha species richness, beta turnover, and the spatial beta diversity. Sugarcane supported higher species richness, demonstrating the potential for conservation at local scales in human-modified landscapes. In contrast, beta diversity was highest in urban areas, likely driven by spatial and temporal variation in plant composition within the urban landscapes. Thus, while improving conservation on human-modified landscapes may improve local alpha richness, conserving variation in natural vegetation is critical for maintaining high beta diversity.

RevDate: 2019-01-08

Cutting KA, Ferguson JM, Anderson ML, et al (2018)

Linking beaver dam affected flow dynamics to upstream passage of Arctic grayling.

Ecology and evolution, 8(24):12905-12917 pii:ECE34728.

Beaver reintroductions and beaver dam structures are an increasingly utilized ecological tool for rehabilitating degraded streams, yet beaver dams can potentially impact upstream fish migrations. We collected two years of data on Arctic grayling movement through a series of beaver dams in a low gradient mountain stream, utilizing radio-telemetry techniques, to determine how hydrology, dam characteristics, and fish attributes impeded passage and movement rates of spawning grayling. We compared fish movement between a "normal" flow year and a "low" flow year, determined grayling passage probabilities over dams in relation to a suite of factors, and predicted daily movement rates in relation to the number of dams each fish passed and distance between dams during upstream migration to spawning areas. We found that the average passage probability over unbreached beaver dams was 88%, though we found that it fell below 50% at specific dams. Upstream passage of grayling was affected by three main characteristics: (a) temperature, (b) breach status, and (c) hydrologic linkages that connect sections of stream above and below the dam. Other variables influence passage, but to a lesser degree. Cumulative passage varied with distance upstream and total number of dams passed in low versus normal flow years, while movement rates upstream slowed as fish swam closer to dams. Our findings demonstrate that upstream passage of fish over beaver dams is strongly correlated with hydrologic conditions with moderate controls by dam- and fish-level characteristics. Our results provide a framework that can be applied to reduce barrier effects when and where beaver dams pose a significant threat to the upstream migration of fish populations while maintaining the diverse ecological benefits of beaver activity when dams are not a threat to fish passage.

RevDate: 2019-01-08

Balmer B, Zolman E, Rowles T, et al (2018)

Ranging patterns, spatial overlap, and association with dolphin morbillivirus exposure in common bottlenose dolphins (Tursiops truncatus) along the Georgia, USA coast.

Ecology and evolution, 8(24):12890-12904 pii:ECE34727.

During 2013-2015, an outbreak of dolphin morbillivirus (DMV) occurred in the western North Atlantic, which resulted in the stranding of over 1,600 common bottlenose dolphins (Tursiops truncatus). There are currently five coastal and 10 bay, sound, and estuary dolphin stocks along the U.S. Atlantic coast, yet there is very limited understanding of which stocks were exposed to DMV during the recent outbreak, or how DMV was transmitted across stocks. In order to address these questions, information is needed on spatial overlap and stock interactions. The goals of this project were to determine ranging patterns, prevalence of DMV, and spatial overlap of the South Carolina-Georgia (SC-GA) Coastal Stock, and adjacent Southern Georgia Estuarine System (SGES) Stock. During September 2015, a health assessment and telemetry study was conducted in which 19 dolphins were captured, tested for antibodies to DMV, and satellite tagged. Dolphins were classified into one of three ranging patterns (Coastal, Sound, or Estuary) based upon telemetry data. Coastal dolphins (likely members of the SC-GA Coastal Stock) had a significantly higher prevalence of positive DMV antibody titers (0.67; N = 2/3), than Sound and Estuary dolphins (likely members of the SGES Stock) (0.13; N = 2/16). These results suggest that the SC-GA Coastal Stock may have experienced greater exposure to DMV as compared to the SGES Stock. However, due to the small size of the SGES Stock and its exposure to high levels of persistent contaminants, this stock may be particularly vulnerable to DMV infection in the future.

RevDate: 2019-01-08

Scherber C, Andert H, Niedringhaus R, et al (2018)

A barrier island perspective on species-area relationships.

Ecology and evolution, 8(24):12879-12889 pii:ECE34726.

Predictions of species richness by island area are a classical cornerstone in ecology, while the specific features of barrier islands have been little appreciated. Many shorelines are occupied by barrier islands, which are shaped by offshore sedimentation processes and annual storm tide events. Hence, the appearance of these islands may vary between years if they are not protected by dykes. Here, we analyzed more than 2,990 species across 36 taxonomic groups (including vertebrates, invertebrates, and land plants) on German barrier islands, the East Frisian Islands. We tested for relationships between species richness or species incidence and island area (SAR), island habitat diversity and further island parameters using a range of generalized linear and mixed-effects models. Overall species richness was explained best by habitat diversity (Shannon index of habitat types). Analyses on the occurrence probability of individual species showed that changes of barrier island area by sedimentation and erosion, that is, barrier island-specific dynamics, explained the occurrence of 17 of 34 taxa, including most beetles, plants, and birds. Only six taxa such as spiders (249 species) and mammals (27 species) were primarily related to area. The diversity of habitat types was a key predictor for the incidence of twenty-five taxa, including ground beetles, true bugs and grasshoppers, amphibians, and reptiles. Overall, richness and incidence of taxa differed greatly in their responses, with area (although varying from 0.1 to 38.9 km2) playing a minor and island heterogeneity a major role, while barrier island-specific sedimentation and erosion turned out to additionally explain species richness and occurrence.

RevDate: 2019-01-08

Curry CM, Ross JD, Contina AJ, et al (2018)

Varying dataset resolution alters predictive accuracy of spatially explicit ensemble models for avian species distribution.

Ecology and evolution, 8(24):12867-12878 pii:ECE34725.

Species distribution models can be made more accurate by use of new "Spatiotemporal Exploratory Models" (STEMs), a type of spatially explicit ensemble model (SEEM) developed at the continental scale that averages regional models pixel by pixel. Although SEEMs can generate more accurate predictions of species distributions, they are computationally expensive. We compared the accuracies of each model for 11 grassland bird species and examined whether they improve accuracy at a statewide scale for fine and coarse predictor resolutions. We used a combination of survey data and citizen science data for 11 grassland bird species in Oklahoma to test a spatially explicit ensemble model at a smaller scale for its effects on accuracy of current models. We found that only four species performed best with either a statewide model or SEEM; the most accurate model for the remaining seven species varied with data resolution and performance measure. Policy implications: Determination of nonheterogeneity may depend on the spatial resolution of the examined dataset. Managers should be cautious if any regional differences are expected when developing policy from range-wide results that show a single model or timeframe. We recommend use of standard species distribution models or other types of nonspatially explicit ensemble models for local species prediction models. Further study is necessary to understand at what point SEEMs become necessary with varying dataset resolutions.

RevDate: 2019-01-08

Balfour VL, Aumont C, Dougherty LR, et al (2018)

The fitness effects of a pale mutant in the aposematic seed bug Lygaeus simulans indicate pleiotropy between warning coloration and life history.

Ecology and evolution, 8(24):12855-12866 pii:ECE34723.

Conspicuous warning colors that signal chemical or other defenses are common in the natural world. For instance, such aposematic warning patterns of red-and-black or yellow-and-black are common among insect taxa, particularly in the order Hemiptera, often forming the basis of Batesian and/or Müllerian mimicry rings. In addition, it has been repeatedly noted that color polymorphisms or mutants that influence pigmentation can show pleiotropy with other behavioral, physiological, or life-history traits. Here, we describe a pale mutant of the seed bug Lygaeus simulans that appeared in our laboratory population in 2012, which differs in color to the wild-type bugs. Through multigenerational experimental crosses between wild-type and pale mutant L. simulans, we first show that the pale phenotype segregates as a single Mendelian locus, with the pale allele being recessive to the wild type. Next, we show (a) that there is a large heterozygous advantage in terms of fecundity, (b) that pale females suffer reduced longevity, and (c) that pale males have increased body length compared to wild-type homozygotes. Our data therefore suggest that the color locus is pleiotropic with a number of life-history traits, opening the door for a more complete genetic analysis of aposematic coloration in this species. In addition, this phenotype will be useful as a visible genetic marker, providing a tool for investigating sperm competition and other post-copulatory drivers of sexual selection in this species.

RevDate: 2019-01-08

Andriollo T, Ashrafi S, Arlettaz R, et al (2018)

Porous barriers? Assessment of gene flow within and among sympatric long-eared bat species.

Ecology and evolution, 8(24):12841-12854 pii:ECE34714.

Species are the basic units for measuring biodiversity and for comprehending biological interactions. Yet, their delineation is often contentious, especially in groups that are both diverse and phenotypically conservative. Three cryptic species of long-eared bats, Plecotus auritus, P. austriacus, and P. macrobullaris, co-occur over extensive areas of Western Europe. The latter is a fairly recent discovery, questioning the overall diversity of the entire Plecotus complex. Yet, high morphological and acoustic similarities compromise the reliable identification of long-eared bats in the field. We postulate that such extensive phenotypic overlap, along with the recurrent observation of morphologically intermediate individuals, may hide rampant interspecific hybridization. Based on a geographic sampling centered on areas of sympatry in the Alps and Corsica, we assessed the level of reproductive isolation of these three Plecotus species with mitochondrial and nuclear markers, looking at both inter- and intraspecific genetic population structuring. No sign of hybridization was detected between these three species that appear well separated biologically. Genetic structuring of populations, however, reflected different species-specific responses to environmental connectivity, that is, to the presence of orographic or sea barriers. While the Alpine range and the Ligurian Sea coincided with sharp genetic discontinuities in P. macrobullaris and P. austriacus, the more ubiquitous P. auritus showed no significant population structuration. There were clear phylogeographic discrepancies between microsatellite and mitochondrial markers at the intraspecific level, however, which challenges the reliance on simple barcoding approaches for the delineation of sound conservation units.

RevDate: 2019-01-08

Benowitz KM, Sparks ME, McKinney EC, et al (2018)

Variation in mandible development and its relationship to dependence on parents across burying beetles.

Ecology and evolution, 8(24):12832-12840 pii:ECE34713.

Background: In species with parental care, there is striking variation in offspring dependence at birth, ranging from feeding independence to complete dependency on parents for nutrition. Frequently, highly dependent offspring further evolve reductions or alterations of morphological traits that would otherwise promote self-sufficiency. Here, we examine evidence for morphological evolution associated with dependence in burying beetles (Nicrophorus spp.), in which dependence upon parents appears to have several independent origins. In many species, precocial first instar larvae can survive without parenting, but several altricial species die at this stage on their own. We focused specifically on the mandibles, which are expected to be related to feeding ability and therefore independence from parents.

Results: We find no evidence that the size of the mandible is related to dependence on parents. However, we do find a developmental and phylogenetic correlation between independence and the presence of serrations on the inner edge of the mandible. Mandibles of independent species bear serrations at hatching, whereas dependent species hatch with smooth mandibles, only developing serrations in the second instar when these larvae gain the ability to survive on their own. Phylogenetic evidence suggests that serrations coincide with independence repeatedly. We note a single exception to this trend, a beetle with a serrated mandible that cannot survive without parents. However, this exception occurs in a species that has recently evolved the loss of independence.

Conclusions: We argue that the absence of mandible serrations occurs due to alternative selection pressures incurred in larvae dependent upon parents to survive. We suggest that this may have led to a variable function for mandibles, perhaps related to increased competitive ability among siblings or increased efficiency in receiving nutrition from parents. Furthermore, we propose that the phylogenetic pattern we see is consistent with the long-held evolutionary hypothesis that evolutionary change in behavior and physiology precede morphological change.

RevDate: 2019-01-08

Stiffler LL, Schroeder KM, Anderson JT, et al (2018)

Quantitative acoustic differentiation of cryptic species illustrated with King and Clapper rails.

Ecology and evolution, 8(24):12821-12831 pii:ECE34711.

Reliable species identification is vital for survey and monitoring programs. Recently, the development of digital technology for recording and analyzing vocalizations has assisted in acoustic surveying for cryptic, rare, or elusive species. However, the quantitative tools that exist for species differentiation are still being refined. Using vocalizations recorded in the course of ecological studies of a King Rail (Rallus elegans) and a Clapper Rail (Rallus crepitans) population, we assessed the accuracy and effectiveness of three parametric (logistic regression, discriminant function analysis, quadratic discriminant function analysis) and six nonparametric (support vector machine, CART, Random Forest, k-nearest neighbor, weighted k-nearest neighbor, and neural networks) statistical classification methods for differentiating these species by their kek mating call. We identified 480 kek notes of each species and quantitatively characterized them with five standardized acoustic parameters. Overall, nonparametric classification methods outperformed parametric classification methods for species differentiation (nonparametric tools were between 57% and 81% accurate, parametric tools were between 57% and 60% accurate). Of the nine classification methods, Random Forest was the most accurate and precise, resulting in 81.1% correct classification of kek notes to species. This suggests that the mating calls of these sister species are likely difficult for human observers to tell apart. However, it also implies that appropriate statistical tools may allow reasonable species-level classification accuracy of recorded calls and provide an alternative to species classification where other capture- or genotype-based survey techniques are not possible.

RevDate: 2019-01-08

Riesle-Sbarbaro SA, Amponsah-Mensah K, de Vries S, et al (2018)

The Gambian epauletted fruit bat shows increased genetic divergence in the Ethiopian highlands and in an area of rapid urbanization.

Ecology and evolution, 8(24):12803-12820 pii:ECE34709.

The Gambian epauletted fruit bat (Epomophorus gambianus) is an abundant species that roosts in both urban and rural settings. The possible role of E. gambianus as a reservoir host of zoonotic diseases underlines the need to better understand the species movement patterns. So far, neither observational nor phylogenetic studies have identified the dispersal range or behavior of this species. Comparative analyses of mitochondrial and nuclear markers from 20 localities across the known distribution of E. gambianus showed population panmixia, except for the populations in Ethiopia and southern Ghana (Accra and Ve-Golokwati). The Ethiopian population may be ancestral and is highly divergent to the species across the rest of its range, possibly reflecting isolation of an ancient colonization along an east-west axis. Mitochondrial haplotypes in the Accra population display a strong signature of a past bottleneck event; evidence of either an ancient or recent bottleneck using microsatellite data, however, was not detected. Demographic analyses identified population expansion in most of the colonies, except in the female line of descent in the Accra population. The molecular analyses of the colonies from Ethiopia and southern Ghana show gender dispersal bias, with the mitochondrial DNA fixation values over ten times those of the nuclear markers. These findings indicate free mixing of the species across great distances, which should inform future epidemiological studies.

RevDate: 2019-01-08

Chambault P, de Thoisy B, Huguin M, et al (2018)

Connecting paths between juvenile and adult habitats in the Atlantic green turtle using genetics and satellite tracking.

Ecology and evolution, 8(24):12790-12802 pii:ECE34708.

Although it is commonly assumed that female sea turtles always return to the beach they hatched, the pathways they use during the years preceding their first reproduction and their natal origins are most often unknown, as it is the case for juvenile green turtles found in Martinique waters in the Caribbean. Given the oceanic circulation of the Guiana current flowing toward Martinique and the presence of important nesting sites for this species in Suriname and French Guiana, we may assume that a large proportion of the juvenile green turtles found in Martinique are originating from the Suriname-French Guiana beaches. To confirm this hypothesis, we performed mixed stock analysis (MSA) on 40 green turtles sampled in Martinique Island and satellite tracked 31 juvenile green turtles tagged in Martinique to (a) assess their natal origin and (b) identify their destination. Our results from MSA confirm that these juveniles are descendant from females laying on several Caribbean and Atlantic beaches, mostly from Suriname and French Guiana, but also from more southern Brazilian beaches. These results were confirmed by the tracking data as the 10 turtles leaving Martinique headed across the Caribbean-Atlantic region in six different directions and 50% of these turtles reached the Brazilian foraging grounds used by the adult green turtles coming from French Guiana. One turtle left the French Guianan coast to perform the first transatlantic migration ever recorded in juvenile green turtles, swimming toward Guinea-Bissau, which is the most important nesting site for green turtles along the African coast. The extensive movements of the migrant turtles evidenced the crossing of international waters and more than 25 exclusive economic zones, reinforcing the need for an international cooperative network to ensure the conservation of future breeders in this endangered species.

RevDate: 2019-01-08

Foucault Q, Wieser A, Waldvogel AM, et al (2018)

Rapid adaptation to high temperatures in Chironomus riparius.

Ecology and evolution, 8(24):12780-12789 pii:ECE34706.

Effects of seasonal or daily temperature variation on fitness and physiology of ectothermic organisms and their ways to cope with such variations have been widely studied. However, the way multivoltines organisms cope with temperature variations from one generation to the next is still not well understood. The aim of this study was to investigate whether the multivoltine midge Chironomus riparius Meigen (1803) responds mainly via acclimation as predicted by current theories or whether rapid genetic adaptation is involved. To investigate this issue, a common garden approach has been applied. A mix of larvae from five European populations was raised in the laboratory at three different pre-exposure temperatures (PET): 14, 20, and 26°C. After three and five generations, respectively, larvae were exposed to three treatment temperatures (TT): 14, 20, and 26°C. Mortality was monitored for the first 48 hr and after emergence. After three generations, significant mortality rate differences depended on an interaction of PET and TT. This finding supports the hypothesis that chironomids respond rapidly to climatic variation via adaptive mechanisms and to a lesser extent via phenotypic plasticity. The result of the experiment indicates that three generations were sufficient to adapt to warm temperature, decreasing the mortality rate, highlighting the potential for chironomids to rapidly respond to seasonally changing conditions.

RevDate: 2019-01-08

Fu HP, Yuan S, Man DH, et al (2018)

The burrow behavior and influenced factors of a prairie subterranean zokor (Myospalax psilurus).

Ecology and evolution, 8(24):12773-12779 pii:ECE34705.

The Transbaikal zokor (Myospalax psilurus) is a dominant rodent distributed in the meadow steppe of Inner Mongolia in northern China. Due to long history of evolution in subterranean environment, the zokor has an adaptive behavior: sealing burrow entrances. When a burrow is damaged, exposed entrances appear, and within a relatively short time, the zokor would be active in sealing the entrances to reduce risks to its survival. In general, it is thought that zokors avoid light and wind, which is consistent with their behavior of sealing burrow entrances. However, direct evidence from field experimental research has been lacking. This study set up 68 field sampling points in a meadow steppe in Inner Mongolia from August to September, 2014 and used a wind-light isolator to study the effects of wind and light factors on zokor burrow entrance sealing behavior. The results showed that there were no significant correlations between wind or light factors and the frequency of zokor burrow entrance sealing. Therefore, wind and light factors are not direct factors associated with zokors actively sealing burrow entrances.

RevDate: 2019-01-08

Maicher V, Sáfián S, Murkwe M, et al (2018)

Flying between raindrops: Strong seasonal turnover of several Lepidoptera groups in lowland rainforests of Mount Cameroon.

Ecology and evolution, 8(24):12761-12772 pii:ECE34704.

Although seasonality in the tropics is often less pronounced than in temperate areas, tropical ecosystems show seasonal dynamics as well. Nevertheless, individual tropical insects' phenological patterns are still poorly understood, especially in the Afrotropics. To fill this gap, we investigated biodiversity patterns of Lepidoptera communities at three rainforest localities in the foothills of Mount Cameroon, West Africa, one of the wettest places in the world. Our multitaxa approach covered six lepidopteran groups (fruit-feeding butterflies and moths, the families Sphingidae, Saturniidae, and Eupterotidae, and the subfamily Arctiinae of Erebidae) with diverse life strategies. We sampled adults of the focal groups in three distinct seasons. Our sampling included standardized bait trapping (80 traps exposed for 10 days per locality and season) and attraction by light (six full nights per locality and season). Altogether, our dataset comprised 20,576 specimens belonging to 559 (morpho)species of the focal groups. The biodiversity of Lepidoptera generally increased in the high-dry season, and either increased (fruit-feeding moths, Arctiinae, Saturniidae) or decreased (butterflies, Sphingidae) in the transition to the wet season in particular groups. Simultaneously, we revealed a strong species turnover of fruit-feeding Lepidoptera and Arctiinae among the seasons, indicating relatively high specialization of these communities for particular seasons. Such temporal specialization can make the local communities of butterflies and moths especially sensitive to the expected seasonal perturbations caused by the global change. Because of the key role of Lepidoptera across trophic levels, such changes in their communities could strengthen this impact on entire tropical ecosystems.

RevDate: 2019-01-08

Yuan DY, Meng X, Duan CQ, et al (2018)

Effects of water exchange rate on morphological and physiological characteristics of two submerged macrophytes from Erhai Lake.

Ecology and evolution, 8(24):12750-12760 pii:ECE34703.

Growth patterns of aquatic macrophytes have been shown to vary in response to hydrological properties; however, such properties are typically characterized by water level fluctuation, flow velocity, flooding season, and sedimentation, but not by water exchange rate (WER). Herein, we experimentally investigated how WER (three levels: exchange 0%, 20%, and 40% of total water per day) affects water and sediment properties, and the consequences that these variations have on the individual responses of two submerged macrophytes, Hydrilla verticillata and Myriophyllum aquaticum which were planted in two different sediment types (sand and clay). In the experiment without ramets, it was found that turbidity, pH value, and dissolved carbon dioxide concentration of the system water were statistically unaffected by WER, while water dissolved oxygen (DO) concentration and sediment oxidation-reduction potential (ORP, in both sediments) consistently increased with increasing WER, regardless of experimental time. In the experiment containing ramets, biomass accumulation and relative growth rate (RGR) of both species gradually increased with increasing WER regardless of sediment type. The mechanisms were related to (a) increased oxygen availability, as indicated by gradually increased water DO concentration and sediment ORP; and (b) enhanced phosphorus (P) and nitrogen (N) absorbing abilities associated with stimulated root growth, reflected in increased mean root length, specific root length, and the root/above-ground biomass ratio, with increasing WER. Additionally, in the experiments containing ramets, significant linear relationships were consistently detected between sediment ORP and root parameters, root parameters and plant nutrients (N and P), and plant nutrients and plant growth conditions (biomass accumulation and RGR). These results demonstrate that WER plays an important role in determining oxygen availability and thus impacts the growth of submerged macrophytes by altering the ability of roots to absorb nutrients, indicating that ecosystem functions are more sensitive to WER than previously recognized.

RevDate: 2019-01-08

Sohlström EH, Marian L, Barnes AD, et al (2018)

Applying generalized allometric regressions to predict live body mass of tropical and temperate arthropods.

Ecology and evolution, 8(24):12737-12749 pii:ECE34702.

The ecological implications of body size extend from the biology of individual organisms to ecosystem-level processes. Measuring body mass for high numbers of invertebrates can be logistically challenging, making length-mass regressions useful for predicting body mass with minimal effort. However, standardized sets of scaling relationships covering a large range in body length, taxonomic groups, and multiple geographical regions are scarce. We collected 6,212 arthropods from 19 higher-level taxa in both temperate and tropical locations to compile a comprehensive set of linear models relating live body mass to a range of predictor variables. We measured live weight (hereafter, body mass), body length and width of each individual and conducted linear regressions to predict body mass using body length, body width, taxonomic group, and geographic region. Additionally, we quantified prediction discrepancy when using parameters from arthropods of a different geographic region. Incorporating body width into taxon- and region-specific length-mass regressions yielded the highest prediction accuracy for body mass. Using regression parameters from a different geographic region increased prediction discrepancy, causing over- or underestimation of body mass depending on geographical origin and whether body width was included. We present a comprehensive range of parameters for predicting arthropod body mass and provide guidance for selecting optimal scaling relationships. Given the importance of body mass for functional invertebrate ecology and the paucity of adequate regressions to predict arthropod body mass from different geographical regions, our study provides a long-needed resource for quantifying live body mass in invertebrate ecology research.

RevDate: 2019-01-08

Radersma R, Hegg A, Noble DWA, et al (2018)

Timing of maternal exposure to toxic cyanobacteria and offspring fitness in Daphnia magna: Implications for the evolution of anticipatory maternal effects.

Ecology and evolution, 8(24):12727-12736 pii:ECE34700.

Organisms that regularly encounter stressful environments are expected to use cues to develop an appropriate phenotype. Water fleas (Daphnia spp.) are exposed to toxic cyanobacteria during seasonal algal blooms, which reduce growth and reproductive investment. Because generation time is typically shorter than the exposure to cyanobacteria, maternal effects provide information about the local conditions subsequent generations will experience. Here, we evaluate if maternal effects in response to microcystin, a toxin produced by cyanobacteria, represent an inheritance system evolved to transmit information in Daphnia magna. We exposed mothers as juveniles and/or as adults, and tested the offspring's fitness in toxic and non-toxic environments. Maternal exposure until reproduction reduced offspring fitness, both in the presence and in the absence of toxic cyanobacteria. However, this effect was accompanied by a small positive fitness effect, relative to offspring from unexposed mothers, in the presence of toxic cyanobacteria. This effect was mainly elicited in response to maternal exposure to toxic cyanobacteria early in life and less so during reproduction. None of these effects were explained by changes in egg size. A meta-analysis using our and others' experiments suggests that the adaptive value of maternal effects to cyanobacteria exposure is weak at best. We suggest that the beneficial maternal effect in our study is an example of phenotypic accommodation spanning generations, rather than a mechanism evolved to transmit information about cyanobacteria presence between generations.

RevDate: 2019-01-08

Tavalire HF, Beechler BR, Buss PE, et al (2018)

Context-dependent costs and benefits of tuberculosis resistance traits in a wild mammalian host.

Ecology and evolution, 8(24):12712-12726 pii:ECE34699.

Disease acts as a powerful driver of evolution in natural host populations, yet individuals in a population often vary in their susceptibility to infection. Energetic trade-offs between immune and reproductive investment lead to the evolution of distinct life history strategies, driven by the relative fitness costs and benefits of resisting infection. However, examples quantifying the cost of resistance outside of the laboratory are rare. Here, we observe two distinct forms of resistance to bovine tuberculosis (bTB), an important zoonotic pathogen, in a free-ranging African buffalo (Syncerus caffer) population. We characterize these phenotypes as "infection resistance," in which hosts delay or prevent infection, and "proliferation resistance," in which the host limits the spread of lesions caused by the pathogen after infection has occurred. We found weak evidence that infection resistance to bTB may be heritable in this buffalo population (h2 = 0.10) and comes at the cost of reduced body condition and marginally reduced survival once infected, but also associates with an overall higher reproductive rate. Infection-resistant animals thus appear to follow a "fast" pace-of-life syndrome, in that they reproduce more quickly but die upon infection. In contrast, proliferation resistance had no apparent costs and was associated with measures of positive host health-such as having a higher body condition and reproductive rate. This study quantifies striking phenotypic variation in pathogen resistance and provides evidence for a link between life history variation and a disease resistance trait in a wild mammalian host population.

RevDate: 2019-01-08

Downey H, Lewis OT, Bonsall MB, et al (2018)

Insect herbivory on seedlings of rainforest trees: Effects of density and distance of conspecific and heterospecific neighbors.

Ecology and evolution, 8(24):12702-12711 pii:ECE34698.

Natural enemies of plants such as insect herbivores can contribute to structuring and maintaining plant diversity in tropical forests. Most research in this area has focused on the role of specialized enemies and the extent to which herbivory on individual plant species is density-dependent. Relatively few insect herbivores specialize on a single host plant species. Insect herbivores that feed on more than one plant species may link the regeneration dynamics of their host species through "apparent competition" or "apparent mutualism." We investigated herbivory and survival of seedlings of two tropical tree species (Cordia alliodora and Cordia bicolor) in the forests of Barro Colorado Island (Panama). We used experiments and observations to assess seedling fate in relation to the presence of conspecifics and heterospecifics across a range of spatial scales. Herbivory significantly increased seedling mortality and was highest at high local densities of C. alliodora seedlings. There was also evidence that high local densities of C. alliodora increased herbivory on co-occurring C. bicolor seedlings. Synthesis. The elevated rates of seedling herbivory at high densities of conspecifics documented in our study are consistent with the predictions of the Janzen-Connell hypothesis, which explains how so many plant species can coexist in tropical forests. Our data also highlight the possibility that herbivore-mediated density-dependence, facilitated by herbivores that feed on multiple plant species, can also occur across plant species. Enemy-mediated indirect effects of this sort have the potential to structure plant communities.

RevDate: 2019-01-08

Huang XL, Xiao L, He HM, et al (2018)

Effect of rearing conditions on the correlation between larval development time and pupal weight of the rice stem borer, Chilo suppressalis.

Ecology and evolution, 8(24):12694-12701 pii:ECE34697.

A strong positive correlation between development time and body size is commonly assumed. However, the evidence is increasing that the correlation between the two traits can be positive, zero or negative, depending on whether the two traits are under antagonistic or synergistic selection. In the present study, we examined the relation between larval development time and pupal weight of the rice stem borer Chilo suppressalis under laboratory and field conditions. For individuals reared at constant temperatures (22, 25, 28 and 31°C), a longer larval period tended to result in larger pupae, showing a positive correlation between larval development time and pupal weight; whereas for those reared under field conditions, a longer larval period tended to result in smaller pupae at 23.5 and 29.8°C, showing a negative correlation between the two traits. There was no correlation between the two traits at the mean daily temperature of 31°C. At constant temperatures, larval development time shortened significantly as rearing temperature increased, whereas pupae tended to become larger at higher temperatures, although no significant difference was detected among temperatures for pupal weight. Under field conditions, larval development time decreased significantly as the mean daily temperature increased, whereas pupal weight of females increased significantly with the increase in the mean daily temperature, which is an example of the reverse temperature-size rule. Feeding method significantly affected larval development time and pupal weight. For individuals fed on live rice plants, larval development time shortened significantly and pupal weight increased significantly compared with those reared on fresh rice stems.

RevDate: 2019-01-08

Batista MRD, Penha RES, Sofia SH, et al (2018)

Comparative analysis of adaptive and neutral markers of Drosophila mediopunctata populations dispersed among forest fragments.

Ecology and evolution, 8(24):12681-12693 pii:ECE34696.

Comparison of adaptive and neutral genetic markers is a valuable approach to characterize the evolutionary consequences of populations living in environments threatened by anthropogenic disturbances, such as forest fragmentation. Shifts in allele frequencies, low genetic variability, and a small effective population size can be considered clear signs of forest fragmentation effects (due to genetic drift) over natural populations, while adaptive responses correlate with environmental variables. Brazilian Atlantic Forest had its landscape drastically reduced and fragmented. Now, several forest remnants are isolated from each other by urban and crop areas. We sampled Drosophila mediopunctata populations from eight forest remnants dispersed on two adjacent geomorphological regions, which are physiognomic and climatically quite distinct. Microsatellite data of inversion-free chromosomes (neutral genetic marker) indicate low structuration among populations suggesting that they were panmictic and greatly influenced by gene flow. Moreover, significant differences in chromosomal inversion frequencies (adaptive genetic marker) among populations and their correlations with climatic and geographical variables indicate that genetic divergence among populations could be an adaptive response to their environment. Nonetheless, we observed a significant difference in inversion frequencies of a population in two consecutive years that may be associated with edge and demographic effects. Also, it may be reflecting seasonal changes of inversion frequencies influenced by great temperature variation due to edge effects. Moreover, the forest fragment size does not affect genetic variation of neutral markers. Our data indicate that despite oscillations in chromosomal inversion frequencies, D. mediopunctata populations from Brazilian Atlantic Forest and their divergence may be driven by adaptive factors to local differences, perhaps because it is a small flying insect easily carried by the wind increasing its migration rates.

RevDate: 2019-01-08

Thakur MP, Griffin JN, Künne T, et al (2018)

Temperature effects on prey and basal resources exceed that of predators in an experimental community.

Ecology and evolution, 8(24):12670-12680 pii:ECE34695.

Climate warming alters the structure of ecological communities by modifying species interactions at different trophic levels. Yet, the consequences of warming-led modifications in biotic interactions at higher trophic levels on lower trophic groups are lesser known. Here, we test the effects of multiple predator species on prey population size and traits and subsequent effects on basal resources along an experimental temperature gradient (12-15°C, 17-20°C, and 22-25°C). We experimentally assembled food web modules with two congeneric predatory mites (Hypoaspis miles and Hypoaspis aculeifer) and two Collembola prey species (Folsomia candida and Proisotoma minuta) on a litter and yeast mixture as the basal resources. We hypothesized that warming would modify interactions within and between predator species, and that these alterations would cascade to basal resources via changes in the density and traits (body size and lipid: protein ratio) of the prey species. The presence of congeners constrained the growth of the predatory species independent of warming despite warming increased predator density in their respective monocultures. We found that warming effects on both prey and basal resources were greater than the effects of predator communities. Our results further showed opposite effects of warming on predator (increase) and prey densities (decrease), indicating a warming-induced trophic mismatch, which are likely to alter food web structures. We highlight that warmer environments can restructure food webs by its direct effects on lower trophic groups even without modifying top-down effects.

RevDate: 2019-01-08

Hart KM, Iverson AR, Fujisaki I, et al (2018)

Sympatry or syntopy? Investigating drivers of distribution and co-occurrence for two imperiled sea turtle species in Gulf of Mexico neritic waters.

Ecology and evolution, 8(24):12656-12669 pii:ECE34691.

Animals co-occurring in a region (sympatry) may use the same habitat (syntopy) within that region. A central aim in ecology is determining what factors drive species distributions (i.e., abiotic conditions, dispersal limitations, and/or biotic interactions). Assessing the degree of biotic interactions can be difficult for species with wide ranges at sea. This study investigated the spatial ecology of two sea turtle species that forage on benthic invertebrates in neritic GoM waters: Kemp's ridleys (Lepidochelys kempii) and loggerheads (Caretta caretta). We used satellite tracking and modeled behavioral modes, then calculated individual home ranges, compared foraging areas, and determined extent of co-occurrence. Using six environmental variables and principal component analysis, we assessed similarity of chosen foraging sites. We predicted foraging location (eco-region) based on species, nesting site, and turtle size. For 127 turtles (64 Kemp's ridleys, 63 loggerheads) tracked from 1989 to 2013, foraging home ranges were nine to ten times larger for Kemp's ridleys than for loggerheads. Species intersected off all U.S. coasts and the Yucatán Peninsula, but co-occurrence areas were small compared to species' distributions. Kemp's ridley foraging home ranges were concentrated in the northern GoM, whereas those for loggerheads were concentrated in the eastern GoM. The two species were different in all habitat variables compared (latitude, longitude, distance to shore, net primary production, mean sea surface temperature, and bathymetry). Nesting site was the single dominant variable that dictated foraging ecoregion. Although Kemp's ridleys and loggerheads may compete for resources, the separation in foraging areas, significant differences in environmental conditions, and importance of nesting location on ecoregion selection (i.e., dispersal ability) indicate that adult females of these species do not interact greatly during foraging and that dispersal and environmental factors more strongly determine their distributions. These species show sympatry in this region but evidence for syntopy was rare.

RevDate: 2019-01-08

Heppenheimer E, Brzeski KE, Hinton JW, et al (2018)

High genomic diversity and candidate genes under selection associated with range expansion in eastern coyote (Canis latrans) populations.

Ecology and evolution, 8(24):12641-12655 pii:ECE34688.

Range expansion is a widespread biological process, with well-described theoretical expectations associated with the colonization of novel ranges. However, comparatively few empirical studies address the genomic outcomes accompanying the genome-wide consequences associated with the range expansion process, particularly in recent or ongoing expansions. Here, we assess two recent and distinct eastward expansion fronts of a highly mobile carnivore, the coyote (Canis latrans), to investigate patterns of genomic diversity and identify variants that may have been under selection during range expansion. Using a restriction-associated DNA sequencing (RADseq), we genotyped 394 coyotes at 22,935 SNPs and found that overall population structure corresponded to their 19th century historical range and two distinct populations that expanded during the 20th century. Counter to theoretical expectations for populations to bottleneck during range expansions, we observed minimal evidence for decreased genomic diversity across coyotes sampled along either expansion front, which is likely due to hybridization with other Canis species. Furthermore, we identified 12 SNPs, located either within genes or putative regulatory regions, that were consistently associated with range expansion. Of these 12 genes, three (CACNA1C, ALK, and EPHA6) have putative functions related to dispersal, including habituation to novel environments and spatial learning, consistent with the expectations for traits under selection during range expansion. Although coyote colonization of eastern North America is well-publicized, this study provides novel insights by identifying genes associated with dispersal capabilities in coyotes on the two eastern expansion fronts.

RevDate: 2019-01-08

Larue B, Côté SD, St-Laurent MH, et al (2018)

Natal habitat preference induction in large mammals-Like mother, like child?.

Ecology and evolution, 8(24):12629-12640 pii:ECE34685.

Habitat selection has received considerable attention from ecologists during the last decades, yet the underlying forces shaping individual differences in habitat selection are poorly documented. Some of these differences could be explained by the early experience of individuals in their natal habitat. By selecting habitat attributes like those encountered early in life, individuals could improve resource acquisition, survival, and ultimately fitness. This behavior, known as natal habitat preference induction (NHPI), could be particularly common in large mammals, because offspring generally stay with their mother for an extended period. We used three complementary approaches to assess NHPI in a marked population of woodland caribou (Rangifer tarandus caribou): (a) population-based resource selection functions (RSFs), (b) individual-based RSFs, and (c) behavioral repeatability analyses. All approaches compared the behavior of calves in their natal range to their behavior as independent subadults during the snow-covered (Dec-Apr) and snow-free (May-Nov) seasons. Using RSFs, we found that the magnitude of habitat selection between calf and subadult stages differed for most covariates, yet the signs of statistically significant effects (selection vs. avoidance) were generally the same. We also found that some habitat selection tactics were highly repeatable across life stages. Notably, caribou responses to habitat disturbances were highly repeatable year-round, meaning that different individuals reacted differently, but consistently, to disturbances. This study highlights the potential role of natal habitat preference induction in shaping individual differences in habitat selection in large mammals and provides valuable knowledge for the management and conservation of a threatened species.

RevDate: 2019-01-08

de Lima HS, Las-Casas FMG, Ribeiro JR, et al (2018)

Ecological and phylogenetic predictors of mobbing behavior in a tropical dry forest.

Ecology and evolution, 8(24):12615-12628 pii:ECE34683.

Mobbing represents a well-known anti-predatory behavior, where potential prey display aggressively against a predator. Despite considerable experimental and descriptive work, no models predict species participation in mobbing assemblages. Here, we aimed to understand why some bird species engage in this behavior, while others do not, and what factors can be used to predict mobbing engagement within an avian community. We investigated whether certain functional traits, such as body size, foraging guild, foraging mode, and strata, as well species abundance and evolutionary relatedness, are important mobbing predictors. To address these goals, we simulated the presence of the Ferruginous Pygmy-Owl (Glaucidium brasilianum) by broadcasting its voice in 230 experiments conducted in 115 points, systematically distributed in a dry forest of northeastern Brazil. We compared these results to 162 avian surveys (point counts) conducted in the same area. Our avian surveys detected 108 bird species (local avian community), whereas our playback experiments attracted 72 species (mobbing assemblage). In general, small, canopy insectivorous or frugivorous birds dominated the mobs. The best mobbing predictors were body mass and guild, whereas species abundance, foraging mode, and strata were not retained in the best models. We found a strong phylogenetic component in body mass and mobbing propensity (almost 90% of the species and individuals participating in the mobs were passerines). At the community level, we found significant differences in the functional and phylogenetic structure of the mobbing assemblage in relation to the avian community. Our results suggest that mobbing behavior is tightly associated with predation risk and the capacity of individual species to find and detect predators, and that functional and phylogenetic features can predict species participation in this complex animal behavior.

RevDate: 2019-01-02

Weiner A, J Enninga (2018)

The Pathogen-Host Interface in Three Dimensions: Correlative FIB/SEM Applications.

Trends in microbiology pii:S0966-842X(18)30273-7 [Epub ahead of print].

Pathogens survive and propagate within host cells through a wide array of complex interactions. Tracking the molecular and cellular events by multidimensional fluorescence microscopy has been a widespread tool for research on intracellular pathogens. Through major advancements in 3D electron microscopy, intracellular pathogens can also be visualized in their cellular environment to an unprecedented level of detail within large volumes. Recently, multidimensional fluorescence microscopy has been correlated with volume electron microscopy, combining molecular and functional information with the overall ultrastructure of infection events. In this review, we provide a short introduction to correlative focused ion beam/scanning electron microscopy (c-FIB/SEM) tomography and illustrate its utility for intracellular pathogen research through a series of studies on Shigella, Salmonella, and Brucella cellular invasion. We conclude by discussing current limitations of and prospects for this approach.

RevDate: 2019-01-02

Spinler JK, Karri V, KD Hirschi (2018)

Planting the Microbiome.

Trends in microbiology pii:S0966-842X(18)30277-4 [Epub ahead of print].

Plant-derived microRNAs stabilized by species-specific lipid nanoparticles mediate interkingdom communication through bacterial intermediates and impact consumer health. Ingested by distinct gut bacteria, these microRNA-containing particles alter bacterial gene expression to affect host immunity. This three-kingdom interplay provides compelling approaches for health-directed dietary interventions for consumers.

RevDate: 2019-01-01

Zhou H, Visnovska T, Gong H, et al (2018)

Contrasting patterns of coding and flanking region evolution in mammalian keratin associated protein-1 genes.

Molecular phylogenetics and evolution pii:S1055-7903(18)30646-8 [Epub ahead of print].

Mammalian genomes contain a number of duplicated genes, and sequence identity between these duplicates can be maintained by purifying selection. However, between-duplicate recombination can also maintain sequence identity between copies, resulting in a pattern known as concerted evolution where within-genome repeats are more similar to each other than to orthologous repeats in related species. Here we investigated the tandemly-repeated keratin-associated protein 1 (KAP1) gene family, KRTAP1, which encodes proteins that are important components of hair and wool in mammals. Comparison of eutherian mammal KRTAP1 gene repeats within and between species shows a strong pattern of concerted evolution. However, in striking contrast to the coding regions of these genes, we find that the flanking regions have a divergent pattern of evolution. This contrast in evolutionary pattern transitions abruptly near the start and stop codons of the KRTAP1 genes. We reveal that this difference in evolutionary patterns is not explained by conventional purifying selection, nor is it likely a consequence of codon adaptation or reverse transcription of KRTAP1-n mRNA. Instead, the evidence suggests that these contrasting patterns result from short-tract gene conversion events that are biased to the KRTAP1 coding region by selection and/or differential sequence divergence. This work demonstrates the power that gene conversion has to finely shape the evolution of repetitive genes, and provides another distinctive pattern of contrasting evolutionary outcomes that results from gene conversion. A greater emphasis on exploring the evolution of multi-gene eukaryotic families will reveal how common different contrasting evolutionary patterns are in gene duplicates.

RevDate: 2019-01-01

Hu S, Ryan LE, Kaymak E, et al (2018)

Multi-modal regulation of C. elegans hermaphrodite spermatogenesis by the GLD-1-FOG-2 complex.

Developmental biology pii:S0012-1606(18)30186-6 [Epub ahead of print].

Proper germ cell sex determination in Caenorhabditis nematodes requires a network of RNA-binding proteins (RBPs) and their target mRNAs. In some species, changes in this network enabled limited XX spermatogenesis, and thus self-fertility. In C. elegans, one of these selfing species, the global sex-determining gene tra-2 is regulated in germ cells by a conserved RBP, GLD-1, via the 3' untranslated region (3'UTR) of its transcript. A C. elegans-specific GLD-1 cofactor, FOG-2, is also required for hermaphrodite sperm fate, but how it modifies GLD-1 function is unknown. Germline feminization in gld-1 and fog-2 null mutants has been interpreted as due to cell-autonomous elevation of TRA-2 translation. Consistent with the proposed role of FOG-2 in translational control, the abundance of nearly all GLD-1 target mRNAs (including tra-2) is unchanged in fog-2 mutants. Epitope tagging reveals abundant TRA-2 expression in somatic tissues, but an undetectably low level in wild-type germ cells. Loss of gld-1 function elevates germline TRA-2 expression to detectable levels, but loss of fog-2 function does not. A simple quantitative model of tra-2 activity constrained by these results can successfully sort genotypes into normal or feminized groups. Surprisingly, fog-2 and gld-1 activity enable the sperm fate even when GLD-1 cannot bind to the tra-2 3' UTR. This suggests the GLD-1-FOG-2 complex regulates uncharacterized sites within tra-2, or other mRNA targets. Finally, we quantify the RNA-binding capacities of dominant missense alleles of GLD-1 that act genetically as "hyper-repressors" of tra-2 activity. These variants bind RNA more weakly in vitro than does wild-type GLD-1. These results indicate that gld-1 and fog-2 regulate germline sex via multiple interactions, and that our understanding of the control and evolution of germ cell sex determination in the C. elegans hermaphrodite is far from complete.

RevDate: 2019-01-01

Gantchoff M, Wang G, Beyer D, et al (2018)

Scale-dependent home range optimality for a solitary omnivore.

Ecology and evolution, 8(23):12271-12282 pii:ECE34690.

Spatial and temporal heterogeneity are fundamental mechanisms structuring home ranges. Under optimality, an individual should structure their space use economically to maximize fitness. We evaluated support for three hypotheses related to range optimality in American black bears (Ursus americanus), predicting (a) range location on a landscape will correspond with high vegetation productivity, (b) increasing forest fragmentation will result in larger ranges, and (c) increasing proportion of forest and/or mean vegetation productivity will result in smaller ranges. We used black bear radio telemetry data from Michigan (2009-2015), Missouri (2010-2016), and Mississippi (2008-2017), USA. Annual space use excluded winter, and we separated seasonal space use into spring, summer, and fall. We collected data from 143 bears (80 females, 63 males), resulting in 97 annual and 538 seasonal ranges. We used generalized linear mixed models to evaluate productivity (estimated through Normalized Difference Vegetation Index [NDVI]) selection, and range size (km2) variation between individuals. At the annual scale, black bears consistently selected areas with greater vegetation productivity than the surrounding landscape; yet selection weakened and was more variable seasonally. Opposite to our prediction, we found that increasing fragmentation consistently resulted in smaller ranges; non-forested land covers and forest edges might provide greater abundance or more diverse foods for bears. Ranges with a greater proportion of forest were smaller, likely reflecting an increase in food and cover which could reduce movements, yet there was no support for more productive ranges also being smaller as expected from an area minimizing strategy. Black bears displayed a scale-dependent space use strategy: at larger spatial and temporal scales, productivity acted as the strongest limiting factor and energy maximizing was the dominant strategy, while an area minimizing strategy was exhibited seasonally. We revealed consistent, scale-dependent responses by black bears to environmental conditions, demonstrating the intrinsic plasticity of this adaptable omnivore.

RevDate: 2019-01-01

Auld JR (2018)

The effects of diet and mating system on reproductive (and post-reproductive) life span in a freshwater snail.

Ecology and evolution, 8(23):12260-12270 pii:ECE34689.

The length of the reproductive life span, along with the number/frequency/magnitude of reproductive events, quantifies an individual's potential contribution to the next generation. By examining reproductive life span, and distinguishing it from somatic life span, we gain insight into critical aspects of an individual's potential fitness as well as reproductive and somatic senescence. Additionally, differentiating somatic and reproductive life spans can provide insight into the existence of a post-reproductive period and factors that shape its duration. Given the known importance of diet and mating system on resource allocation, I reared individual freshwater snails (Physa acuta) from 22 full-sib families under a 2 × 2 factorial design that crossed mate availability (available [outcrossing] or not [selfing]) and diet (Spirulina or lettuce) and quantified aspects of the entire life history enabling me to distinguish reproductive and somatic life spans, determine the total number of reproductive events, and evaluate how the reproductive rate changes with age. Overall, mated snails experienced shorter reproductive and somatic life spans; a diet of Spirulina also shortened both reproductive and somatic life spans. A post-reproductive period existed in all conditions; its duration was proportional to somatic but not reproductive life span. I evaluate several hypotheses for the existence and duration of the post-reproductive period, including a novel hypothesis that the post-reproductive period may result from an increase in reproductive interval with age. I conclude that the post-reproductive period may be indicative of a randomly timed death occurring as the interval between reproductive events continues to increase. As such, a "post-reproductive" period can be viewed as a by-product of a situation where reproductive senescence outpaces somatic senescence.

RevDate: 2019-01-01

Muola A, JA Stenberg (2018)

Folivory has long-term effects on sexual but not on asexual reproduction in woodland strawberry.

Ecology and evolution, 8(23):12250-12259 pii:ECE34687.

Plant fitness is often a result of both sexual and asexual reproductive success and, in perennial plants, over several years. Folivory can affect both modes of reproduction. However, little is known about the effects of folivory on resource allocation to the two modes of reproduction simultaneously and across years. In a 2-year common garden experiment, we examined the effects of different levels of folivory by the strawberry leaf beetle, Galerucella tenella, on current growth, as well as current and future sexual and asexual reproduction (runners) of perennial woodland strawberry, Fragaria vesca. In addition, we measured the chlorophyll content in leaves in the year of experimental damage to determine whether there was increased photosynthetic activity, and, thus, a compensatory response to herbivory. Finally, we tested whether the previous year's folivory, as a result of its effect on plant fitness, affected the level of natural herbivory the plant experienced during the subsequent year. In the year of experimental damage, plants that were exposed to moderate and high levels of folivory (25% and 50% leaf area consumed, respectively) increased their photosynthetic activity compared to control plants. However, only plants exposed to high folivory exhibited negative effects, with a lower probability of flowering compared to control plants, indicating that plants exposed to low or moderate folivory were able to compensate for the damage. Negative effects of folivory were carried over to the subsequent year. Plants that were exposed to moderate folivory (25% leaf area consumed) during first year produced fewer flowers and fruits in the subsequent year. Runner production was consistently unaffected by folivory. The effects of experimental folivory on the level of natural herbivory were mediated via its effects on plant fitness. Our results show that the negative effects of folivory only influence sexual reproduction in woodland strawberry. Furthermore, even though woodland strawberry can tolerate moderate amounts of folivory in the short term, the negative effects on fitness appear later; this highlights the importance of studying the effects of herbivory over consecutive years in perennial plants.

RevDate: 2019-01-01

de Souza AC, Portela RCQ, EA de Mattos (2018)

Demographic processes limit upward altitudinal range expansion in a threatened tropical palm.

Ecology and evolution, 8(23):12238-12249 pii:ECE34686.

Understanding the factors that determine species' range limits is a key issue in ecology, and is fundamental for biodiversity conservation under widespread global environmental change. Elucidating how altitudinal variation affects demographic processes may provide important clues for understanding the factors limiting current and future species distributions, yet population dynamics at range limits are still poorly understood. Here, we tested the hypothesis that lower abundance at a species' upper altitudinal range limit is related to lower vital rates. We compared the dynamics of two populations of the tropical palm Euterpe edulis, located near and at the edge of its altitudinal limit of distribution in the Brazilian Atlantic Forest. Data from four annual censuses, from 2012 to 2015, were used. We used matrix population models to estimate asymptotic population growth rates and the elasticity values for the vital rates of the two populations of E. edulis. Life table response experiments were used to compare population performance by measuring the contribution of each vital rate to population growth rates. Population growth rates were not significantly different from one in either population, indicating that both populations were stable during the study period. However, the abundance of all ontogenetic stages was lower at the altitudinal range limit, which was related to decreases in some vital rates, especially fecundity. Additionally, there were higher elasticity values for the survival of immatures and reproductive individuals, compared to all other vital rates, in both populations. Synthesis. Our results show that even a small-scale environmental variation near range limits is sufficient to drive changes in the demography of this threatened palm. A minor increase in elevation approaching the limit of altitudinal distribution may reduce environmental suitability and affect population vital rates, thus contributing to setting upper altitudinal range limits for plants.

RevDate: 2019-01-01

Singh SP, Groeneveld JC, Hart-Davis MG, et al (2018)

Seascape genetics of the spiny lobster Panulirus homarus in the Western Indian Ocean: Understanding how oceanographic features shape the genetic structure of species with high larval dispersal potential.

Ecology and evolution, 8(23):12221-12237 pii:ECE34684.

This study examines the fine-scale population genetic structure and phylogeography of the spiny lobster Panulirus homarus in the Western Indian Ocean. A seascape genetics approach was used to relate the observed genetic structure based on 21 microsatellite loci to ocean circulation patterns, and to determine the influence of latitude, sea surface temperature (SST), and ocean turbidity (KD490) on population-level processes. At a geospatial level, the genetic clusters recovered corresponded to three putative subspecies, P. h. rubellus from the SW Indian Ocean, P. h. megasculptus from the NW Indian Ocean, and P. h. homarus from the tropical region in-between. Virtual passive Lagrangian particles advected using satellite-derived ocean surface currents were used to simulate larval dispersal. In the SW Indian Ocean, the dispersion of particles tracked over a 4-month period provided insight into a steep genetic gradient observed at the Delagoa Bight, which separates P. h. rubellus and P. h. homarus. South of the contact zone, particles were advected southwestwards by prevailing boundary currents or were retained in nearshore eddies close to release locations. Some particles released in southeast Madagascar dispersed across the Mozambique Channel and reached the African shelf. Dispersal was characterized by high seasonal and inter-annual variability, and a large proportion of particles were dispersed far offshore and presumably lost. In the NW Indian Ocean, particles were retained within the Arabian Sea. Larval retention and self-recruitment in the Arabian Sea could explain the recent genetic divergence between P. h. megasculptus and P. h. homarus. Geographic distance and minimum SST were significantly associated with genetic differentiation in multivariate analysis, suggesting that larval tolerance to SST plays a role in shaping the population structure of P. homarus.

RevDate: 2019-01-01

Larrue S, Butaud JF, Daehler CC, et al (2018)

Persistence at the final stage of volcanic island ontogeny: Abiotic predictors explain native plant species richness on 111 remote Pacific atolls.

Ecology and evolution, 8(23):12208-12220 pii:ECE34680.

Aim: The final island ontogeny of the general dynamic model (GDM) (i.e., before island submergence) in tropical oceans corresponds to the coral atoll stage. Here, we examined whether the species richness of native vascular plants (indigenous and endemic species) on atolls is controlled by spatial and/or physical processes. We also predicted that atolls strongly affected by anthropogenic disturbance would have lower native species richness than predicted by spatial and physical processes.

Location: Marshall Islands, Kiribati Islands, Nauru, Niue, Johnston, Cook Islands, French Polynesia and Pitcairn Islands (Pacific Ocean).

Taxon: Native vascular plants.

Methods: We used stepwise regression to test the relative influence of five biogeographic variables on native species richness. Relationships were assessed for the full set of 111 Pacific coral atolls, as well as for atoll subsets ranging from 9 to 45 atolls. An index of human impact was then estimated, and residuals in the regression model predicting species richness from biogeographic variables were compared with the level of human impact.

Results: A regression model including atoll area, highest atoll elevation, the stepping stone distances from the nearest raised atoll and volcanic island explained native species richness on the 111 Pacific coral atolls. Regression models for different archipelagos and atoll subsets were also significant. Endemic species richness was significantly linked with highest atoll elevation and the stepping stone distances from the nearest raised atoll. Residuals in the biogeographic regression model were barely related to human impact across the 111 atolls but were significantly related to human impact in the Kiribati atolls.

Main conclusions: Native species richness on atolls is mainly controlled by physical and spatial characteristics. However, anthropogenic disturbances have altered the predicted pattern of native species richness leading to a lower model fit in some atoll subsets.

RevDate: 2019-01-01

Rodriguez-Casariego JA, Ladd MC, Shantz AA, et al (2018)

Coral epigenetic responses to nutrient stress: Histone H2A.X phosphorylation dynamics and DNA methylation in the staghorn coral Acropora cervicornis.

Ecology and evolution, 8(23):12193-12207 pii:ECE34678.

Nutrient pollution and thermal stress constitute two of the main drivers of global change in the coastal oceans. While different studies have addressed the physiological effects and ecological consequences of these stressors in corals, the role of acquired modifications in the coral epigenome during acclimatory and adaptive responses remains unknown. The present work aims to address that gap by monitoring two types of epigenetic mechanisms, namely histone modifications and DNA methylation, during a 7-week-long experiment in which staghorn coral fragments (Acropora cervicornis) were exposed to nutrient stress (nitrogen, nitrogen + phosphorus) in the presence of thermal stress. The major conclusion of this experiment can be summarized by two main results: First, coral holobiont responses to the combined effects of nutrient enrichment and thermal stress involve the post-translational phosphorylation of the histone variant H2A.X (involved in responses to DNA damage), as well as nonsignificant modifications in DNA methylation trends. Second, the reduction in H2A.X phosphorylation (and the subsequent potential impairment of DNA repair mechanisms) observed after prolonged coral exposure to nitrogen enrichment and thermal stress is consistent with the symbiont-driven phosphorus limitation previously observed in corals subject to nitrogen enrichment. The alteration of this epigenetic mechanism could help to explain the synergistic effects of nutrient imbalance and thermal stress on coral fitness (i.e., increased bleaching and mortality) while supporting the positive effect of phosphorus addition to improving coral resilience to thermal stress. Overall, this work provides new insights into the role of epigenetic mechanisms during coral responses to global change, discussing future research directions and the potential benefits for improving restoration, management and conservation of coral reef ecosystems worldwide.

RevDate: 2019-01-01

Jones W, Kulma K, Bensch S, et al (2018)

Interspecific transfer of parasites following a range-shift in Ficedula flycatchers.

Ecology and evolution, 8(23):12183-12192 pii:ECE34677.

Human-induced climate change is expected to cause major biotic changes in species distributions and thereby including escalation of novel host-parasite associations. Closely related host species that come into secondary contact are especially likely to exchange parasites and pathogens. Both the Enemy Release Hypothesis (where invading hosts escape their original parasites) and the Novel Weapon Hypothesis (where invading hosts bring new parasites that have detrimental effects on native hosts) predict that the local host will be most likely to experience a disadvantage. However, few studies evaluate the occurrence of interspecific parasite transfer by performing wide-scale geographic sampling of pathogen lineages, both within and far from host contact zones. In this study, we investigate how haemosporidian (avian malaria) prevalence and lineage diversity vary in two, closely related species of passerine birds; the pied flycatcher Ficedula hypoleuca and the collared flycatcher F. albicollis in both allopatry and sympatry. We find that host species is generally a better predictor of parasite diversity than location, but both prevalence and diversity of parasites vary widely among populations of the same bird species. We also find a limited and unidirectional transfer of parasites from pied flycatchers to collared flycatchers in a recent contact zone. This study therefore rejects both the Enemy Release Hypothesis and the Novel Weapon Hypothesis and highlights the complexity and importance of studying host-parasite relationships in an era of global climate change and species range shifts.

RevDate: 2019-01-01

Fukui S, May-McNally SL, Taylor EB, et al (2018)

Maladaptive secondary sexual characteristics reduce the reproductive success of hybrids between native and non-native salmonids.

Ecology and evolution, 8(23):12173-12182 pii:ECE34676.

Human-mediated hybridization between introduced and native species is one of the most serious threats to native taxa. Although field studies have attempted to quantify the relative fitness or reproductive success of parental species and their hybrids, only a few studies have unraveled the factors determining the fitness of hybrids. Here, we hypothesized that maladaptive secondary sexual characteristics may reduce fitness of hybrids between two fish species. To test this, we evaluated the reproductive success of introduced brook trout (BT: Salvelinus fontinalis), native white-spotted charr (WSC: S. leucomaenis) and their hybrids in a natural stream in Hokkaido, Japan, where the two parental species show remarkably different male secondary sexual characteristics, such as elongated jaws and deeper bodies. We predicted that introgression from WSC is maladaptive for BT males because the BT male has more prominent secondary sexual characteristics. Our results suggest that both sexual selection and outbreeding depression in males and females significantly influence an individual's reproductive success. Our results also suggest that asymmetric introgression may increase the risks to persistence in the recipient species.

RevDate: 2019-01-01

Song X, Zeng X, D Tian (2018)

Allocation of forest net primary production varies by forest age and air temperature.

Ecology and evolution, 8(23):12163-12172 pii:ECE34675.

Carbon partition among plant parts has a vital influence not only on the growth of individual plants but also on decomposition, carbon and nitrogen sequestration, and plant-atmosphere water exchange. Although many studies have tried to reveal plant growth mechanisms using observational living biomass or the biomass ratio among different organs, knowledge and understanding about carbon partition is still scarce and exists much uncertainty. In this work, a dataset about 1,089 sample plots of natural forests downloaded from the Chinese Ecosystem Research Network (CERN) was used to explore the dependences of net primary production (NPP) partition among foliage, stem and branch, and root on forest age, and mean annual temperature (MAT). The results found that (a) for all forest types, NPP partition had a significant relationship with forest age (p < 0.0001), that is, younger plants usually allocated a higher proportion of the NPP to stems, branches, and roots. As plants aged, an increasing proportion of the NPP was allocated to foliage; (b) MAT was negatively correlated with the proportions of the NPP allocated to foliage (Fleaf; %) and roots (Froot; %), while proportions of the NPP allocated to stems and branches (Fstbr; %) were positively dependent on MAT; (c) independent effect analysis demonstrated that forest age had a larger direct influence on Fleaf and Froot, while MAT was relatively important for Fstbr; and (d) forest age and MAT had a stronger combined effect on NPP allocation for broad-leaved forests, while for needled-leaved forests, the influences of forest age and MAT existed large differences among different forest types. This work not only is important for understanding the contribution of climatic factor and forest age on forest NPP partition, but also provides valuable ideas for developing ecological models.

RevDate: 2019-01-01

Westphal MF, Noble T, Butterfield HS, et al (2018)

A test of desert shrub facilitation via radiotelemetric monitoring of a diurnal lizard.

Ecology and evolution, 8(23):12153-12162 pii:ECE34673.

Preservation of desert ecosystems is a worldwide conservation priority. Shrubs can play a key role in the structure of desert communities and can function as foundation species. Understanding desert shrub ecology is therefore an important task in desert conservation. A useful model for the function of shrubs in deserts is ecological facilitation, which explores benefits that shrubs confer on their community. Facilitation has been well developed in the context of shrub-plant interactions but less well studied for plant-animal interactions. We used radiotelemetry to test the hypothesis that a dominant desert shrub facilitates one species of diurnal lizard. We hypothesized that the blunt-nosed leopard lizard Gambelia sila would spend some part of its daily activity cycle associated with California jointfir Ephedra californica, and that lizard association with shrubs would increase during the afternoon peak temperature period. We relocated lizards three times daily for 24 days and scored whether lizards were within 0.5 m of a shrub, which we used as an indicator of shrub association. For each relocation, we also scored lizard association with a set of predefined microhabitat features. We also scored lizard behavior according to a set of predefined behavioral traits. We constructed home ranges following the minimum convex polygon method and generated estimates of shrub density and relative shrub area within each home range polygon. We obtained 1,190 datapoints from a sample of 27 lizards. We found that lizards were associated with open sites significantly more often than with shrubs but were associated with shrubs more than predicted by percent shrub area within their home ranges. Lizards were associated significantly more often under shrubs during the afternoon peak temperature period, and lizards were observed cooling under shrubs significantly more often. The frequency of association of individual lizards with shrubs was not correlated with the density of shrubs within their home range. Synthesis and Applications. Shrubs can be considered as a component of high-quality habitat for ectothermic desert vertebrates for the purposes of restoration and management. Furthermore, radiotelemetry provides a novel methodological approach for assessing shrub-animal facilitative interactions within desert communities.

RevDate: 2019-01-01

Fairweather R, Bradbury IR, Helyar SJ, et al (2018)

Range-wide genomic data synthesis reveals transatlantic vicariance and secondary contact in Atlantic cod.

Ecology and evolution, 8(23):12140-12152 pii:ECE34672.

Recent advances in genetic and genomic analysis have greatly improved our understanding of spatial population structure in marine species. However, studies addressing phylogeographic patterns at oceanic spatial scales remain rare. In Atlantic cod (Gadus morhua), existing range-wide examinations suggest significant transatlantic divergence, although the fine-scale contemporary distribution of populations and potential for secondary contact are largely unresolved. Here, we explore transatlantic phylogeography in Atlantic cod using a data-synthesis approach, integrating multiple genome-wide single-nucleotide polymorphism (SNP) datasets representative of different regions to create a single range-wide dataset containing 1,494 individuals from 54 locations and genotyped at 796 common loci. Our analysis highlights significant transatlantic divergence and supports the hypothesis of westward post-glacial colonization of Greenland from the East Atlantic. Accordingly, our analysis suggests the presence of transatlantic secondary contact off eastern North America and supports existing perspectives on the phylogeographic history of Atlantic cod with an unprecedented combination of genetic and geographic resolution. Moreover, we demonstrate the utility of integrating distinct SNP databases of high comparability.

RevDate: 2019-01-01

Zhang R, Schellenberg MP, Han G, et al (2018)

Drought weakens the positive effects of defoliation on native rhizomatous grasses but enhances the drought-tolerance traits of native caespitose grasses.

Ecology and evolution, 8(23):12126-12139 pii:ECE34671.

The objective of this study was to evaluate the drought tolerance, compensatory growth, and different plant traits between two native perennial caespitose grasses and two native rhizomatous grasses in response to drought and defoliation. A randomized complete block design at the Swift Current Research and Development Centre (SCRDC) of Agriculture and Agri-Food Canada (AAFC) examined the effects of water stress and clipping on the plant biomass, plant morphological traits, and relative leaf chlorophyll content (SPAD value) of four native grasses (caespitose grass: Hesperostipa comata and H. curtiseta; rhizomatous grass: Pascopyrum smithii and Elymus lanceolatus). Drought drastically decreased the shoot and root biomass, plant height, number of tillers and leaf growth of P. smithii and E. lanceolatus, as well as the rhizome biomass and R/S ratio of P. smithii. Defoliation had a positive effect on the shoot biomass of P. smithii and E. lanceolatus under well water treatments (100% and 85% of field capacity). However, the compensatory growth of P. smithii and E. lanceolatus significantly declined with increased water stress. In addition, there are no significant changes in plant biomass, plant height, number of tillers and leaves, and SPAD value of H. comata and H. curtiseta under relative dry condition (70% of field capacity). Consequently, these results demonstrated that the rhizomatous grasses possessed a stronger compensation in response to defoliation under wet conditions, but the positive effects of defoliation can be weakened by drought. The caespitose grasses (Hesperostipa species) exhibited a greater drought tolerance than rhizomatous grasses due to the relatively stable plant traits in response to water stress.

RevDate: 2019-01-01

Ellis TD, JH Cushman (2018)

Indirect effects of a large mammalian herbivore on small mammal populations: Context-dependent variation across habitat types, mammal species, and seasons.

Ecology and evolution, 8(23):12115-12125 pii:ECE34670.

Multiple consumer species frequently co-occur in the same landscape and, through effects on surrounding environments, can interact in direct and indirect ways. These interactions can vary in occurrence and importance, and focusing on this variation is critical for understanding the dynamics of interactions among consumers. Large mammalian herbivores are important engineers of ecosystems worldwide, have substantial impacts on vegetation, and can indirectly affect small-mammal populations. However, the degree to which such indirect effects vary within the same system has received minimal attention. We used a 16-year-old exclosure experiment, stratified across a heterogeneous landscape, to evaluate the importance of context-dependent interactions between tule elk (Cervus canadensis nannodes) and small mammals (deer mice [Peromyscus maniculatus], meadow voles [Microtus californicus], and harvest mice [Reithrodontymys megalotis]) in a coastal grassland in California. Effects of elk on voles varied among habitats and seasons: In open grasslands, elk reduced vole numbers during fall 2013 but not summer 2014; in Lupinus-dominated grasslands, elk reduced vole numbers during summer 2014 but not fall 2013; and in Baccharis-dominated grasslands, elk had no effect on vole numbers in either season. Effects of elk on the two mice species also varied among habitats and seasons, but often in different ways from voles and each other. In fall 2013, elk decreased mice abundances in Lupinus-dominated grasslands, but not in Baccharis-dominated or open grasslands. In summer 2014, elk decreased the abundance of harvest mice consistently across habitat types. In contrast, elk increased deer-mice numbers in open grasslands but not other habitats. Within the same heterogenous study system, the influence of elk on small mammals was strongly context-dependent, varying among habitats, mammal species, and seasons. We hypothesize that such variability is common in nature and that failure to consider it may yield inaccurate findings and limit our understanding of interactions among co-occurring consumers.

RevDate: 2019-01-01

Barnard AA, JP Masly (2018)

Divergence in female damselfly sensory structures is consistent with a species recognition function but shows no evidence of reproductive character displacement.

Ecology and evolution, 8(23):12101-12114 pii:ECE34669.

Males and females transmit and receive signals prior to mating that convey information such as sex, species identity, or individual condition. In some animals, tactile signals relayed during physical contact between males and females before and during mating appear to be important for mate choice or reproductive isolation. This is common among odonates, when a male grasps a female's thorax with his terminal appendages prior to copulation, and the female subsequently controls whether copulation occurs by bending her abdomen to complete intromission. It has been hypothesized that mechanosensory sensilla on the female thoracic plates mediate mating decisions, but is has been difficult to test this idea. Here, we use North American damselflies in the genus Enallagma (Odonata: Coenagrionidae) to test the hypothesis that variation in female sensilla traits is important for species recognition. Enallagma anna and E. carunculatum hybridize in nature, but experience strong reproductive isolation as a consequence of divergence in male terminal appendage morphology. We quantified several mechanosensory sensilla phenotypes on the female thorax among multiple populations of both species and compared divergence in these traits in sympatry versus allopatry. Although these species differed in features of sensilla distribution within the thoracic plates, we found no strong evidence of reproductive character displacement among the sensilla traits we measured in regions of sympatry. Our results suggest that species-specific placement of female mechanoreceptors may be sufficient for species recognition, although other female sensory phenotypes might have diverged in sympatry to reduce interspecific hybridization.

RevDate: 2019-01-01

Russell K, D Van Sanford (2018)

Breeding for resilience to increasing temperatures: A field trial assessing genetic variation in soft red winter wheat.

Ecology and evolution, 8(23):12090-12100 pii:ECE34668.

Breeding for resilience to climate change is a daunting prospect. Crop and climate models tell us that global wheat yields are likely to decline as the climate warms, causing a significant risk to global food security. High temperatures are known to affect crop development yet breeding for tolerance to heat stress is difficult to achieve in field environments. We conducted an active warming study over two years to quantify the effects of heat stress on genetic variation of soft red winter (SRW) wheat (Triticum aestivum L.). Forty SRW cultivars and breeding lines were chosen based on marker genotypes at photoperiod sensitivity and reduced height loci. These genotypes were planted in a randomized complete block design replicated twice across two environments, ambient and artificially warmed. Average heading date occurred 5 days earlier in the warmed environment than in the ambient environment over both years (p ≤ 0.05). On average, grain yield was significantly reduced in the warmed environment by 211.41 kg/ha (p ≤ 0.05) or 4.84%, though we identified 13 genotypes with increased yield in response to warming in both years. Of these genotypes, eight had significantly increased N uptake while six showed significantly increased N utilization efficiency under warming. Under warming, genotypes with wild-type alleles at the Rht-D1 locus display significantly greater yields (p ≤ 0.01) and biomass (p ≤ 0.001) than genotypes with reduced height alleles. Of the 13 genotypes with higher (p ≤ 0.01) yields under warming, nine have the wild-type allele at the Rht-D1 locus in addition to being photoperiod insensitive. The next steps will be to validate these findings in other populations and to develop an efficient breeding/phenotyping scheme that will lead to more resilient cultivars.

RevDate: 2019-01-01

Yıldırım Y, Tinnert J, A Forsman (2018)

Contrasting patterns of neutral and functional genetic diversity in stable and disturbed environments.

Ecology and evolution, 8(23):12073-12089 pii:ECE34667.

Genetic structure among and diversity within natural populations is influenced by a combination of ecological and evolutionary processes. These processes can differently influence neutral and functional genetic diversity and also vary according to environmental settings. To investigate the roles of interacting processes as drivers of population-level genetic diversity in the wild, we compared neutral and functional structure and diversity between 20 Tetrix undulata pygmy grasshopper populations in disturbed and stable habitats. Genetic differentiation was evident among the different populations, but there was no genetic separation between stable and disturbed environments. The incidence of long-winged phenotypes was higher in disturbed habitats, indicating that these populations were recently established by flight-capable colonizers. Color morph diversity and dispersion of outlier genetic diversity, estimated using AFLP markers, were higher in disturbed than in stable environments, likely reflecting that color polymorphism and variation in other functionally important traits increase establishment success. Neutral genetic diversity estimated using AFLP markers was lower in disturbed habitats, indicating stronger eroding effects on neutral diversity of genetic drift associated with founding events in disturbed compared to stable habitats. Functional diversity and neutral diversity were negatively correlated across populations, highlighting the utility of outlier loci in genetics studies and reinforcing that estimates of genetic diversity based on neutral markers do not infer evolutionary potential and the ability of populations and species to cope with environmental change.

RevDate: 2019-01-01

Heinze J, Hanoeffner M, Delabie JHC, et al (2018)

Methuselah's daughters: Paternal age has little effect on offspring number and quality in Cardiocondyla ants.

Ecology and evolution, 8(23):12066-12072 pii:ECE34666.

Male age may directly or indirectly affect the fitness of their female mating partners and their joint progeny. While in some taxa of insects, old males make better mates and fathers, young males excel in others. Males of most social Hymenoptera are relatively short lived and because of testis degeneration have only a limited sperm supply. In contrast, the wingless fighter males of the ant Cardiocondyla obscurior live for several weeks and produce sperm throughout their lives. Wingless males engage in lethal combat with rival males and the winner of such fights can monopolize mating with all female sexuals that emerge in their nests over a prolonged timespan. Here, we investigate if male age has an influence on sperm quality, the queen's lifespan and productivity, and the size and weight of their offspring. Queens mated to one-week or six-week-old males did not differ in life expectancy and offspring production, but the daughters of young males were slightly heavier than those of old males. Our data suggest negligible reproductive senescence of C. obscurior males even at an age, which only few of them reach. This matches the reproductive strategy of Cardiocondyla ants, in which freshly emerging female sexuals rarely have the option to mate with males other than the one present in their natal nest.

RevDate: 2019-01-01

Sandamal S, Tennakoon A, Meng QL, et al (2018)

Population genetics and evolutionary history of the wild rice species Oryza rufipogon and O. nivara in Sri Lanka.

Ecology and evolution, 8(23):12056-12065 pii:ECE34665.

Genetic diversity and population genetic structure of the wild rice species Oryza rufipogon and O. nivara in Sri Lanka were studied using 33 microsatellite markers. A total of 315 individuals of 11 natural populations collected from the wet, intermediate, and dry zones of the country were used in the study. We found a moderate to high level of genetic diversity at the population level, with the polymorphic loci (P) ranging from 60.6% to 100% (average 81.8%) and the expected heterozygosity (HE) varying from 0.294 to 0.481 (average 0.369). A significant genetic differentiation between species and strong genetic structure within species were also observed. Based on species distribution modeling, we detected the dynamics of the preferred habitats for the two species in Sri Lanka and demonstrated that both O. rufipogon and O. nivara populations have expanded substantially since the last internal glacial. In addition, we showed that the geographical distribution of the two species corresponded to the climate zones and identified a few of key environmental variables that contribute to the distribution of the two species, implying the potential mechanism for ecological adaptation of these two species in Sri Lanka. These studies provided important insights into the population genetics and evolution of these wild species in Sri Lanka and are of great significance to the in situ conservation and utilization of these wild resources in genetic improvement of rice.

RevDate: 2019-01-01

Rozins C, Silk MJ, Croft DP, et al (2018)

Social structure contains epidemics and regulates individual roles in disease transmission in a group-living mammal.

Ecology and evolution, 8(23):12044-12055 pii:ECE34664.

Population structure is critical to infectious disease transmission. As a result, theoretical and empirical contact network models of infectious disease spread are increasingly providing valuable insights into wildlife epidemiology. Analyzing an exceptionally detailed dataset on contact structure within a high-density population of European badgers Meles meles, we show that a modular contact network produced by spatially structured stable social groups, lead to smaller epidemics, particularly for infections with intermediate transmissibility. The key advance is that we identify considerable variation among individuals in their role in disease spread, with these new insights made possible by the detail in the badger dataset. Furthermore, the important impacts on epidemiology are found even though the modularity of the Badger network is much lower than the threshold that previous work suggested was necessary. These findings reveal the importance of stable social group structure for disease dynamics with important management implications for socially structured populations.

RevDate: 2019-01-01

Savva I, Bennett S, Roca G, et al (2018)

Thermal tolerance of Mediterranean marine macrophytes: Vulnerability to global warming.

Ecology and evolution, 8(23):12032-12043 pii:ECE34663.

The Mediterranean Sea is warming at three times the rate of the global ocean raising concerns about the vulnerability of marine organisms to climate change. Macrophytes play a key role in coastal ecosystems, therefore predicting how warming will affect these key species is critical to understand the effects of climate change on Mediterranean coastal ecosystems. We measured the physiological performance of six dominant native Mediterranean macrophytes under ten temperature treatments ranging from 12 to 34°C to examine their thermal niche, and vulnerability to projected warming in the western Mediterranean up until 2100. Among the macrophytes tested, Cymodocea nodosa was the species with the highest thermal optima and it was beyond current summer temperature. Therefore, C. nodosa may benefit from projected warming over the coming century. The optimal temperature for growth of the other species (Posidonia oceanica, Cystoseira compressa, Padina pavonica, Caulerpa prolifera, and Halimeda tuna) was lower. Similarly, the species presented different upper lethal limits, spanning at least across 5.1°C between 28.9°C (P. oceanica) and >34°C (C. nodosa). Our results demonstrate the variable physiological responses of species within the same local community to temperature changes and highlight important potential differences in climate change vulnerability, among species within coastal marine ecosystems.

RevDate: 2019-01-01

Martinez AS, Willoughby JR, MR Christie (2018)

Genetic diversity in fishes is influenced by habitat type and life-history variation.

Ecology and evolution, 8(23):12022-12031 pii:ECE34661.

Populations of fishes are increasingly threatened by over-exploitation, pollution, habitat destruction, and climate change. In order to better understand the factors that can explain the amount of genetic diversity in wild populations of fishes, we collected estimates of genetic diversity (mean heterozygosity and mean rarefied number of alleles per locus) along with habitat associations, conservation status, and life-history information for 463 fish species. We ran a series of phylogenetic generalized least squares models to determine which factors influence genetic diversity in fishes after accounting for shared evolutionary history among related taxa. We found that marine fishes had significantly higher genetic diversity than freshwater fishes with marine fishes averaging 11.3 more alleles per locus than their freshwater counterparts. However, contrary to our expectations, genetic diversity was not found to be lower in threatened versus not-threatened fishes. Finally, we found that both age at maturity and fecundity were negatively related to genetic variation in both marine and freshwater fishes. Our results demonstrate that both life-history characteristics and habitat play a role in shaping patterns of genetic diversity in fishes and should be considered when prioritizing species for conservation.

RevDate: 2019-01-01

Lonsinger RC, Adams JR, LP Waits (2018)

Evaluating effective population size and genetic diversity of a declining kit fox population using contemporary and historical specimens.

Ecology and evolution, 8(23):12011-12021 pii:ECE34660.

Loss of genetic diversity has serious conservation consequences (e.g., loss of adaptive potential, reduced population viability), but is difficult to evaluate without developing long-term, multigenerational datasets. Alternatively, historical samples can provide insights into changes in genetic diversity and effective population size (Ne). Kit foxes (Vulpes macrotis) are a species of conservation concern across much of their range. In western Utah, kit fox abundance has declined precipitously from historical levels, causing concern about population persistence. We analyzed genetic samples from museum specimens and contemporary scats to evaluate temporal changes in (a) genetic diversity and (b) Ne for kit foxes in western Utah, and (c) discuss our findings with respect to population risk and conservation. The Ne of kit foxes in western Utah has decreased substantially. When compared to established conservation thresholds for Ne (e.g., the 50/500 rule), observed levels suggest the population may be at risk of inbreeding depression and local extinction. In contrast, we found no significant decrease in genetic diversity associated with declining Ne. We detected evidence of low levels of immigration into the population and suspect genetic diversity may have been maintained by this previously undescribed gene flow from adjacent populations. Low or intermittent immigration may serve to temper the potential short-term negative consequences of low Ne. We recommend that kit fox conservation efforts focus on evaluating and maintaining landscape connectivity. We demonstrate how historical specimens can provide a baseline of comparison for contemporary populations, highlighting the importance of natural history collections to conservation during a period of declining funding and support.

RevDate: 2019-01-01

Alhassan AM, Ma W, Li G, et al (2018)

Response of soil organic carbon to vegetation degradation along a moisture gradient in a wet meadow on the Qinghai-Tibet Plateau.

Ecology and evolution, 8(23):11999-12010 pii:ECE34656.

The study was conducted during the growing seasons of 2013, 2014, and 2015 in the wet meadows on the eastern Qinghai-Tibet plateau (QTP) in the Gansu Gahai Wetland Nature Reserve to determine the dynamics of soil organic carbon (SOC) as affected by vegetation degradation along a moisture gradient and to assess its relationship with other soil properties and biomass yield. Hence, we measured SOC at depths of 0-10, 10-20, and 20-40 cm under the influence of four categories of vegetation degradation (healthy vegetation [HV], slightly degraded [SD], moderately degraded [MD], and heavily degraded [HD]). Our results showed that SOC decreased with increased degree of vegetation degradation. Average SOC content ranged between 36.18 ± 4.06 g/kg in HD and 69.86 ± 21.78 g/kg in HV. Compared with HV, SOC content reduced by 30.49%, 42.22%, and 48.22% in SD, MD, and HD, respectively. SOC significantly correlated positively with soil water content, aboveground biomass, and belowground biomass, but significantly correlated negatively with soil temperature and bulk density (p < 0.05). Highly Significant positive correlations were also found between SOC and total nitrogen (p = 0.0036), total phosphorus (p = 0.0006) and total potassium (p < 0.0001). Our study suggests that severe vegetation and moisture loss led to approximately 50% loss in SOC content in the wet meadows, implying that under climate warming, vegetation and soil moisture loss will dramatically destabilize carbon sink capacities of wetlands. We therefore suggest wetland hydrological management, restoration of vegetation, plant species protection, regulation of grazing activities, and other anthropogenic activities to stabilize carbon sink capacities of wetlands.

RevDate: 2019-01-01

Feng G, Li JQ, Zang RG, et al (2018)

Variation in three community features across habitat types and scales within a 15-ha subtropical evergreen-deciduous broadleaved mixed forest dynamics plot in China.

Ecology and evolution, 8(23):11987-11998 pii:ECE34655.

The evergreen and deciduous broadleaved mixed forests (EDBMFs) belong to one of the ecosystems most sensitive to environmental change, however, little is known about the environmental determinants for their plant diversity and forest structure at different habitat types and spatial scales. Here, we used data from a 15-ha (300 × 500 m) forest dynamic plot (FDP) of an old-growth EDBMF to examine the patterns and determinants of the three community features (stem abundance, rarefied species richness and basal area [BA]) in three habitat types (ridge, hillside and foothill) and at three spatial scales (20 × 20 m, 50 × 50 m, and 100 × 100 m). We found that the three community features significantly changed with habitat type, but only one of them (rarefied richness) changed with scale. Among spatial scales, the principle environmental factors that widely affected community features were pH, soil organic matter, and total phosphorus, while these effects only taken place at certain habitat. Variations in the three community features explained by soil conditions were generally greater than those explained by topographical conditions. With changes in habitat type, the proportion of variations explained by environmental conditions was 31%-53%, 8%-25%, and 18%-26% for abundance, rarefied richness, and BA, respectively. With increasing spatial scale, the variations explained by environmental conditions were 44%-75% for abundance, 28%-95% for rarefied richness, and 18%-86% for BA. Our study demonstrated that environmental factors had great impacts on the plant diversity and forest structure in the EDBMFs, especially the soil factors such as pH. In addition, the importance of the environmental determinants on these community features was highly related to the spatial scale.

RevDate: 2019-01-01

Alexander HM, Collins CD, Reed AW, et al (2018)

Effects of removing woody cover on long-term population dynamics of a rare annual plant (Agalinis auriculata): A study comparing remnant prairie and oldfield habitats.

Ecology and evolution, 8(23):11975-11986 pii:ECE34654.

Worldwide, grasslands are becoming shrublands/forests. In North America, eastern red cedar (Juniperus virginiana) often colonizes prairies. Habitat management can focus on woody removal, but we often lack long-term data on whether removal leads to population recovery of herbaceous plants without seeding. We undertook a long-term study (17 years) of numbers of the rare annual plant Agalinis auriculata in a gridwork of 100 m2 plots in adjacent prairie and oldfield sites in Kansas, USA. We collected data before and after removal of Juniperus virginiana at the prairie. Plant population sizes were highly variable at both sites and over time. High numbers of plants in a plot 1 year were often followed by low numbers the following year, suggesting negative density-dependence. Plant numbers were lowest with extensive woody cover and with low precipitation. After woody plant removal, A. auriculata increased dramatically in abundance and occupancy in most years; increases were also seen at the oldfield, suggesting later survey years were overall more favorable. Synthesis and applications: Removal of woody plants led to increased numbers of a rare annual prairie plant, without seeding. Multiple years of data were essential for interpretation given extreme temporal variability in numbers. The largest prairie population was 7 years following tree removal, showing that positive effects of management can last this long. This species also fared well in oldfield habitat, suggesting restoration opportunities. Given that land managers are busy, time-efficient field methods and data analysis approaches such as ours offer advantages. In addition to general linear models, we suggest Rank Occupancy-Abundance Profiles (ROAPs), a simple-to-use data visualization and analysis method. Creation of ROAPs for sites before and after habitat management helps reveal the degree to which plant populations are responding to management with changes in local density, changes in occupancy, or both.

RevDate: 2019-01-01

Maruyama A, Sugatani K, Watanabe K, et al (2018)

Environmental DNA analysis as a non-invasive quantitative tool for reproductive migration of a threatened endemic fish in rivers.

Ecology and evolution, 8(23):11964-11974 pii:ECE34653.

Quantitative information regarding reproduction is essential for conserving endangered animals; however, some conventional quantitative methods can be damaging to the target population and their habitats. In the present study, the reproductive migration of a threatened endemic fish, three-lips (Opsariichthys uncirostris uncirostris), was non-invasively monitored by quantitative PCR of species-specific environmental DNA (eDNA), the usefulness of which has been not sufficiently explored. Water sampling and from-shore visual inspection were performed weekly along a tributary of Lake Biwa (Japan), where adult fish seasonally migrate upstream to reproduce as well as at lake sites near the river mouth. Species-specific eDNA was collected at all locations at times when the fish were visually observed and at certain sites where the fish were not observed. Log-transformed individual counts from visual inspection were positively correlated with log-transformed eDNA concentration in the river sites, indicating that eDNA analysis can be a reliable quantitative tool for fish abundance in rivers. Furthermore, distance from the lake did not influence eDNA concentration, suggesting that eDNA transport by river flow had a negligible effect on eDNA quantification. Both eDNA concentration and individual counts gradually increased from May-July, and decreased in August. Importantly, eDNA analysis showed that the fish occupied more habitats in the peak reproductive season and stayed for longer time at any given site. An additional underwater survey confirmed unexpected eDNA detections as true positives. eDNA analysis has great potential to quantitatively monitor reproductive fish migrations under certain conditions.

RevDate: 2019-01-01

Gao S, Zheng Z, Wang Y, et al (2018)

Drought and grazing drive the retrogressive succession by changing the plant-plant interaction of the main species in Inner Mongolia Steppe.

Ecology and evolution, 8(23):11954-11963 pii:ECE34652.

Plant-plant interactions play a key role in the function and structure of communities. The combined effect of drought stress and grazing disturbance on shaping plant-plant interactions is still poorly understood, while this combination is common in semiarid ecosystems. Four species including Stipa grandis, which is dominant in the typical steppe, and Stipa krylovii, Artemisia frigida, and Cleistogenes squarrosa, which are dominant species in the S. grandis degraded communities, were selected as study targets. We conducted a competition experiment (uniformly dense monoculture or mixture, respectively) under controlled conditions, including both drought stress and mowing disturbance, and calculated the relative interaction index (RII) of tiller number and RII of biomass for each species under each condition. (a) Under the same condition, the RII of tiller number and that of biomass for the same species usually showed reverse trends. (b) Mowing disturbance rather than drought stress played a negative role in influencing S. grandis' or S. krylovii's RII of tiller number and played a positive role in influencing A. frigida's RII of biomass. (c) Drought stress rather than mowing disturbance played a positive role in influencing C. squarrosa's RII of tiller number. (d) Neighbor species significantly influenced S. grandis' RII of tiller number, S. krylovii's RII of tiller number, A. frigida's RII of tiller number and biomass, and C. squarrosa's RII of biomass. These results could provide an explanation for why S. krylovii, A. frigida, and C. squarrosa can replace S. grandis and become the dominant species when S. grandis communities undergo a process of degradation due to overgrazing or climatic drought in natural communities. The present study provided powerful evidences for species replacement in the typical steppe of Inner Mongolia and elucidated the driving mechanisms of S. grandis communities' retrogressive succession.

RevDate: 2019-01-01

Hulsey CD, Holzman R, A Meyer (2018)

Dissecting a potential spandrel of adaptive radiation: Body depth and pectoral fin ecomorphology coevolve in Lake Malawi cichlid fishes.

Ecology and evolution, 8(23):11945-11953 pii:ECE34651.

The evolution of body shape reflects both the ecological factors structuring organismal diversity as well as an organism's underlying anatomy. For instance, body depth in fishes is thought to determine their susceptibility to predators, attractiveness to mates, as well as swimming performance. However, the internal anatomy influencing diversification of body depth has not been extensively examined, and changes in body depth could arise as a by-product of functional changes in other anatomical structures. Using an improved phylogenetic hypothesis for a diverse set of Lake Malawi cichlid fishes, we tested the evolutionary association between body depth and the height of the pectoral girdle. To refine the functional importance of the observed substantial correlation, we also tested the coevolution of pectoral girdle height and pectoral fin area. The extensive coevolution of these traits suggests body depth in fishes like the Lake Malawi cichlids could diverge simply as a by-product of being tightly linked to ecomorphological divergence in other functional morphological structures like the pectoral fins.

RevDate: 2019-01-01

Prates I, Penna A, Rodrigues MT, et al (2018)

Local adaptation in mainland anole lizards: Integrating population history and genome-environment associations.

Ecology and evolution, 8(23):11932-11944 pii:ECE34650.

Environmental gradients constrain physiological performance and thus species' ranges, suggesting that species occurrence in diverse environments may be associated with local adaptation. Genome-environment association analyses (GEAA) have become central for studies of local adaptation, yet they are sensitive to the spatial orientation of historical range expansions relative to landscape gradients. To test whether potentially adaptive genotypes occur in varied climates in wide-ranged species, we implemented GEAA on the basis of genomewide data from the anole lizards Anolis ortonii and Anolis punctatus, which expanded from Amazonia, presently dominated by warm and wet settings, into the cooler and less rainy Atlantic Forest. To examine whether local adaptation has been constrained by population structure and history, we estimated effective population sizes, divergence times, and gene flow under a coalescent framework. In both species, divergence between Amazonian and Atlantic Forest populations dates back to the mid-Pleistocene, with subsequent gene flow. We recovered eleven candidate genes involved with metabolism, immunity, development, and cell signaling in A. punctatus and found no loci whose frequency is associated with environmental gradients in A. ortonii. Distinct signatures of adaptation between these species are not associated with historical constraints or distinct climatic space occupancies. Similar patterns of spatial structure between selected and neutral SNPs along the climatic gradient, as supported by patterns of genetic clustering in A. punctatus, may have led to conservative GEAA performance. This study illustrates how tests of local adaptation can benefit from knowledge about species histories to support hypothesis formulation, sampling design, and landscape gradient characterization.

RevDate: 2019-01-01

Ng WT, Cândido de Oliveira Silva A, Rima P, et al (2018)

Ensemble approach for potential habitat mapping of invasive Prosopis spp. in Turkana, Kenya.

Ecology and evolution, 8(23):11921-11931 pii:ECE34649.

Aim: Prosopis spp. are an invasive alien plant species native to the Americas and well adapted to thrive in arid environments. In Kenya, several remote-sensing studies conclude that the genus is well established throughout the country and is rapidly invading new areas. This research aims to model the potential habitat of Prosopis spp. by using an ensemble model consisting of four species distribution models. Furthermore, environmental and expert knowledge-based variables are assessed.

Location: Turkana County, Kenya.

Methods: We collected and assessed a large number of environmental and expert knowledge-based variables through variable correlation, collinearity, and bias tests. The variables were used for an ensemble model consisting of four species distribution models: (a) logistic regression, (b) maximum entropy, (c) random forest, and (d) Bayesian networks. The models were evaluated through a block cross-validation providing statistical measures.

Results: The best predictors for Prosopis spp. habitat are distance from water and built-up areas, soil type, elevation, lithology, and temperature seasonality. All species distribution models achieved high accuracies while the ensemble model achieved the highest scores. Highly and moderately suitable Prosopis spp. habitat covers 6% and 9% of the study area, respectively.

Main conclusions: Both ensemble and individual models predict a high risk of continued invasion, confirming local observations and conceptions. Findings are valuable to stakeholders for managing invaded area, protecting areas at risk, and to raise awareness.

RevDate: 2019-01-01

Kuszewska K, Miler K, Rojek W, et al (2018)

Rebel honeybee workers have a tendency to become intraspecific reproductive parasites.

Ecology and evolution, 8(23):11914-11920 pii:ECE34647.

Worker honeybees may reproduce in either their own or foreign colonies; the latter situation is termed intraspecific reproductive parasitism (IRP). In this study, we compared the tendency for IRP between normal honeybee workers, which are characterized by a relatively low reproductive potential, and "rebel workers", a recently discovered subcaste of honeybee workers characterized by a high reproductive potential that develops when the colony is without a queen. We expected that the high reproductive potential of the rebel workers would influence their reproductive strategy and that these individuals would drift to other colonies to lay eggs more often than normal workers. The results confirm our expectations and show that rebel workers are more likely than normal workers to drift to foreign colonies. The rebel workers also preferred to drift to queenless colonies than to queenright colonies, while the normal workers did not show this preference. This study indicates that rebel workers have a tendency for IRP, which may be responsible for the maintenance of the rebel worker strategy in bee populations.

RevDate: 2019-01-01

Tavares SB, Samarra FIP, Pascoal S, et al (2018)

Killer whales (Orcinus orca) in Iceland show weak genetic structure among diverse isotopic signatures and observed movement patterns.

Ecology and evolution, 8(23):11900-11913 pii:ECE34646.

Local adaption through ecological niche specialization can lead to genetic structure between and within populations. In the Northeast Pacific, killer whales (Orcinus orca) of the same population have uniform specialized diets that are non-overlapping with other sympatric, genetically divergent, and socially isolated killer whale ecotypes. However, killer whales in Iceland show intrapopulation variation of isotopic niches and observed movement patterns: some individuals appear to specialize on herring and follow it year-round while others feed upon herring only seasonally or opportunistically. We investigated genetic differentiation among Icelandic killer whales with different isotopic signatures and observed movement patterns. This information is key for management and conservation purposes but also for better understanding how niche specialization drives genetic differentiation. Photo-identified individuals (N = 61) were genotyped for 22 microsatellites and a 611 bp portion of the mitochondrial DNA (mtDNA) control region. Photo-identification of individuals allowed linkage of genetic data to existing data on individual isotopic niche, observed movement patterns, and social associations. Population subdivision into three genetic units was supported by a discriminant analysis of principal components (DAPC). Genetic clustering corresponded to the distribution of isotopic signatures, mtDNA haplotypes, and observed movement patterns, but genetic units were not socially segregated. Genetic differentiation was weak (FST < 0.1), suggesting ongoing gene flow or recent separation of the genetic units. Our results show that killer whales in Iceland are not as genetically differentiated, ecologically discrete, or socially isolated as the Northeast Pacific prey-specialized killer whales. If any process of ecological divergence and niche specialization is taking place among killer whales in Iceland, it is likely at a very early stage and has not led to the patterns observed in the Northeast Pacific.

RevDate: 2019-01-01

Su J, Aryal A, Hegab IM, et al (2018)

Decreasing brown bear (Ursus arctos) habitat due to climate change in Central Asia and the Asian Highlands.

Ecology and evolution, 8(23):11887-11899 pii:ECE34645.

Around the world, climate change has impacted many species. In this study, we used bioclimatic variables and biophysical layers of Central Asia and the Asian Highlands combined with presence data of brown bear (Ursus arctos) to understand their current distribution and predict their future distribution under the current rate of climate change. Our bioclimatic model showed that the current suitable habitat of brown bear encompasses 3,430,493 km2 in the study area, the majority of which (>65%) located in China. Our analyses demonstrated that suitable habitat will be reduced by 11% (378,861.30 km2) across Central Asia and the Asian Highlands by 2,050 due to climate change, predominantly (>90%) due to the changes in temperature and precipitation. The spatially averaged mean annual temperature of brown bear habitat is currently -1.2°C and predicted to increase to 1.6°C by 2,050. Mean annual precipitation in brown bear habitats is predicted to increase by 13% (from 406 to 459 mm) by 2,050. Such changes in two critical climatic variables may significantly affect the brown bear distribution, ethological repertoires, and physiological processes, which may increase their risk of extirpation in some areas. Approximately 32% (1,124,330 km2) of the total suitable habitat falls within protected areas, which was predicted to reduce to 1,103,912 km2 (1.8% loss) by 2,050. Future loss of suitable habitats inside the protected areas may force brown bears to move outside the protected areas thereby increasing their risk of mortality. Therefore, more protected areas should be established in the suitable brown bear habitats in future to sustain populations in this region. Furthermore, development of corridors is needed to connect habitats between protected areas of different countries in Central Asia. Such practices will facilitate climate migration and connectivity among populations and movement between and within countries.

RevDate: 2019-01-01

Ackiss AS, Bird CE, Akita Y, et al (2018)

Genetic patterns in peripheral marine populations of the fusilier fish Caesio cuning within the Kuroshio Current.

Ecology and evolution, 8(23):11875-11886 pii:ECE34644.

Aim: Mayr's central-peripheral population model (CCPM) describes the marked differences between central and peripheral populations in genetic diversity, gene flow, and census size. When isolation leads to genetic divergence, these peripheral populations have high evolutionary value and can influence biogeographic patterns. In tropical marine species with pelagic larvae, powerful western-boundary currents have great potential to shape the genetic characteristics of peripheral populations at latitudinal extremes. We tested for the genetic patterns expected by the CCPM in peripheral populations that are located within the Kuroshio Current for the Indo-Pacific reef fish, Caesio cuning.

Methods: We used a panel of 2,677 SNPs generated from restriction site-associated DNA (RAD) sequencing to investigate genetic diversity, relatedness, effective population size, and spatial patterns of population connectivity from central to peripheral populations of C. cuning along the Kuroshio Current.

Results: Principal component and cluster analyses indicated a genetically distinct lineage at the periphery of the C. cuning species range and examination of SNPs putatively under divergent selection suggested potential for local adaptation in this region. We found signatures of isolation-by-distance and significant genetic differences between nearly all sites. Sites closest to the periphery exhibited increased within-population relatedness and decreased effective population size.

Main Conclusions: Despite the potential for homogenizing gene flow along the Kuroshio Current, peripheral populations in C. cuning conform to the predictions of the CCPM. While oceanography, habitat availability, and dispersal ability are all likely to shape the patterns found in C. cuning across this central-peripheral junction, the impacts of genetic drift and natural selection in increasing smaller peripheral populations appear to be probable influences on the lineage divergence found in the Ryukyu Islands.

RevDate: 2019-01-01

Shero MR, Goetz KT, Costa DP, et al (2018)

Temporal changes in Weddell seal dive behavior over winter: Are females increasing foraging effort to support gestation?.

Ecology and evolution, 8(23):11857-11874 pii:ECE34643.

In capital-breeding marine mammals, prey acquisition during the foraging trip coinciding with gestation must provide energy to meet the immediate needs of the growing fetus and also a store to meet the subsequent demands of lactation. Weddell seals (Leptonychotes weddellii) that give birth following the gestational (winter) foraging period gain similar proportions of mass and lipid as compared to females that fail to give birth. Therefore, any changes in foraging behavior can be attributed to gestational costs. To investigate differences in foraging effort associated with successful reproduction, twenty-three satellite tags were deployed on post-molt female Weddell seals in the Ross Sea. Of the 20 females that returned to the area the following year, 12 females gave birth and eight did not. Females that gave birth the following year began the winter foraging period with significantly longer and deeper dives, as compared to non-reproductive seals. Mid- to late winter, reproductive females spent a significantly greater proportion of the day diving, and either depressed their diving metabolic rates (DMR), or exceeded their calculated aerobic dive limit (cADL) more frequently than females that returned without a pup. Moreover, non-reproductive females organized their dives into 2-3 short bouts per day on average (BOUTshort; 7.06 ± 1.29 hr; mean ± 95% CI), whereas reproductive females made 1-2 BOUTshort per day (10.9 ± 2.84 hr), comprising one long daily foraging bout without rest. The magnitude of the increase in dive activity budgets and depression in calculated DMR closely matched the estimated energetic requirements of supporting a fetus. This study is one of the first to identify increases in foraging effort that are associated with successful reproduction in a top predator and indicates that reproductive females must operate closer to their physiological limits to support gestational costs.

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RJR Experience and Expertise

Researcher

Robbins holds BS, MS, and PhD degrees in the life sciences. He served as a tenured faculty member in the Zoology and Biological Science departments at Michigan State University. He is currently exploring the intersection between genomics, microbial ecology, and biodiversity — an area that promises to transform our understanding of the biosphere.

Educator

Robbins has extensive experience in college-level education: At MSU he taught introductory biology, genetics, and population genetics. At JHU, he was an instructor for a special course on biological database design. At FHCRC, he team-taught a graduate-level course on the history of genetics. At Bellevue College he taught medical informatics.

Administrator

Robbins has been involved in science administration at both the federal and the institutional levels. At NSF he was a program officer for database activities in the life sciences, at DOE he was a program officer for information infrastructure in the human genome project. At the Fred Hutchinson Cancer Research Center, he served as a vice president for fifteen years.

Technologist

Robbins has been involved with information technology since writing his first Fortran program as a college student. At NSF he was the first program officer for database activities in the life sciences. At JHU he held an appointment in the CS department and served as director of the informatics core for the Genome Data Base. At the FHCRC he was VP for Information Technology.

Publisher

While still at Michigan State, Robbins started his first publishing venture, founding a small company that addressed the short-run publishing needs of instructors in very large undergraduate classes. For more than 20 years, Robbins has been operating The Electronic Scholarly Publishing Project, a web site dedicated to the digital publishing of critical works in science, especially classical genetics.

Speaker

Robbins is well-known for his speaking abilities and is often called upon to provide keynote or plenary addresses at international meetings. For example, in July, 2012, he gave a well-received keynote address at the Global Biodiversity Informatics Congress, sponsored by GBIF and held in Copenhagen. The slides from that talk can be seen HERE.

Facilitator

Robbins is a skilled meeting facilitator. He prefers a participatory approach, with part of the meeting involving dynamic breakout groups, created by the participants in real time: (1) individuals propose breakout groups; (2) everyone signs up for one (or more) groups; (3) the groups with the most interested parties then meet, with reports from each group presented and discussed in a subsequent plenary session.

Designer

Robbins has been engaged with photography and design since the 1960s, when he worked for a professional photography laboratory. He now prefers digital photography and tools for their precision and reproducibility. He designed his first web site more than 20 years ago and he personally designed and implemented this web site. He engages in graphic design as a hobby.

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Collection of publications by R J Robbins

Reprints and preprints of publications, slide presentations, instructional materials, and data compilations written or prepared by Robert Robbins. Most papers deal with computational biology, genome informatics, using information technology to support biomedical research, and related matters.

Research Gate page for R J Robbins

ResearchGate is a social networking site for scientists and researchers to share papers, ask and answer questions, and find collaborators. According to a study by Nature and an article in Times Higher Education , it is the largest academic social network in terms of active users.

Curriculum Vitae for R J Robbins

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Curriculum Vitae for R J Robbins

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