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Bibliography on: Invasive Species

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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 18 Aug 2019 at 01:34 Created: 

Invasive Species

Standard Definition: Invasive species are plants, animals, or pathogens that are non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause harm. Although that definition allows a logical possibility that some species might be non-native and harmless, most of time it seems that invasive species and really bad critter (or weed) that should be eradicated are seen as equivalent phrases. But, there is a big conceptual problem with that notion: every species in every ecosystem started out in that ecosystem as an invader. If there were no invasive species, all of Hawaii would be nothing but bare volcanic rock. Without an invasion of species onto land, there would be no terrestrial ecosystems at all. For the entire history of life on Earth, the biosphere has responded to perturbation and to opportunity with evolutionary innovation and with physical movement. While one may raise economic or aesthetic arguments against invasive species, it is impossible to make such an argument on scientific grounds. Species movement — the occurrence of invasive species — is the way the biosphere responds to perturbation. One might even argue that species movement is the primary, short-term "healing" mechanism employed by the biosphere to respond to perturbation — to "damage." As with any healing process, the short-term effect may be aesthetically unappealing (who thinks scabs are appealing?), but the long-term effects can be glorious.

Created with PubMed® Query: "invasive species" OR "invasion biology" OR "alien species" OR "introduced species" NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-08-16

Jeffrey JD, Jeffries KM, CD Suski (2019)

Physiological status of silver carp (Hypophthalmichthys molitrix) in the Illinois River: An assessment of fish at the leading edge of the invasion front.

Comparative biochemistry and physiology. Part D, Genomics & proteomics, 32:100614 pii:S1744-117X(19)30143-1 [Epub ahead of print].

Silver carp (Hypophthalmichthys molitrix) are invasive to North America, and their range has expanded within the Mississippi River Basin, seemingly unchecked, since their introduction in the late 1970s, with the exception of the upper reaches of the Illinois River. With the imminent threat of their movement into the Great Lakes, the goal of the present study was to assess whether differences in the physiological status between silver carp at the leading edge of their invasion front and core population sites could explain their lack of expansion upstream toward Lake Michigan over the past decade. A transcriptomic approach using RNA sequencing and analysis of plasma variables were used to quantify differences among fish at the leading edge and two downstream core population sites. Leading-edge fish exhibited upregulation of genes associated with xenobiotic defense (e.g., ATP-binding cassette C1 [abcc1], abcc2, abcc6), decreased cell integrity (i.e., macroautophagy and apoptosis; autophagy-related protein 9A [atg9a], caspase 3b [casp3b]), and cholesterol metabolism (e.g., abca1, apolipoprotein A1 [apoa1], sterol O-acyltransferase [soat1]) and downregulation of genes associated with DNA repair (e.g., tumor suppressor p53-binding protein 1 [tp53bp1]) compared to core population sites. Transcriptomic profiles of leading-edge fish were consistent with fish inhabiting a polluted environment and suggest that poorer water quality conditions upstream of the leading edge may represent a non-permanent barrier to silver carp range expansion. The present study provides potential molecular targets for monitoring the physiological status of silver carp over time and in response to future improvements in water quality upstream of their leading edge.

RevDate: 2019-08-16

Niemiec RM, Asner GP, Gaertner JA, et al (2019)

Using spatially explicit, time-dependent analysis to understand how social factors influence conservation outcomes.

Conservation biology : the journal of the Society for Conservation Biology [Epub ahead of print].

Conservation across human-dominated landscapes requires an understanding of the social and ecological factors driving outcomes. Studies that link conservation outcomes to social and ecological factors have examined temporally static patterns. However, there may be different social and ecological processes driving increases and decreases in conservation outcomes that can only be revealed through temporal analyses. Through a case study of the invasion of Falcataria moluccana in Hawaii, we examined the association of social factors with increases and decreases in invader distributions over time and space. Over 7 years, rates of invader decrease varied substantially (66-100%) relative to social factors, such as building value, whether land was privately or publically owned, and primary residence by a homeowner, whereas rates of increase varied only slightly (<0.1-3.6%) relative to such factors. These findings suggest that links between social factors and invasion in the study system may be driven more by landowners controlling existing invasive species, rather than by landowners preventing the spread of invasive species. We suggest that spatially explicit, time-dependent analyses provide a more nuanced understanding of the way social factors influence conservation outcomes. Such an understanding can help managers develop outreach programs and policies targeted at different types of landowners in human-dominated landscapes. Article Impact Statement: Spatially explicit, time-dependent analysis reveals whether social-factor and conservation-outcome links are due to preservation or restoration. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-16

Li ZP, Zhao J, Chen YB, et al (2019)

[Spatial variation and driving factors of invasive plants in Fujian Province, China].

Ying yong sheng tai xue bao = The journal of applied ecology, 30(8):2682-2690.

Based on the field investigation data and the integration GIS spatial methods and geographical detector model, we analyzed the main and interactive effects of geographical and social environmental factors on the distribution of invasive plants in Fujian Province, China. The results showed that a total of 82 invasive plant species were recorded, with Compositae as the dominant family. Conyza canadensis, Ageratum conyzoides, and Alternanthera philoxeroides had the highest frequencies. There were more invasive species in coastal areas than in inland areas. Fuzhou and Xiamen were the hot areas for plant invaision. The invasive plants widely distributed at different altitudes, and the invasion reduced with the increasing altitude. The geographical detector analysis showed that rainfall as a natural environment factor and road density and people density as socio-economy factors were the major driving factors for the distribution of invasive plant species. The multi-factor interaction had a positive effect on the spatial distribution of invasive plants, implying the complexity of impact factors on the distribution of invasive plant species. In conclusion, the geographical detector could be used in the studies of invasive plants, and environmental factors could be also applied for monitoring the suitable establishment areas of invasive plants in Fujian Province. Our results provide a scientific basis for effective management of invasive plants.

RevDate: 2019-08-16

Geladi I, De León LF, Torchin ME, et al (2019)

100-year time series reveal little morphological change following impoundment and predator invasion in two Neotropical characids.

Evolutionary applications, 12(7):1385-1401 pii:EVA12763.

Human activities are dramatically altering ecosystems worldwide, often resulting in shifts in selection regimes. In response, natural populations sometimes undergo rapid phenotypic changes, which, if adaptive, can increase their probability of persistence. However, in many instances, populations fail to undergo any phenotypic change, which might indicate a variety of possibilities, including maladaptation. In freshwater ecosystems, the impoundment of rivers and the introduction of exotic species are among the leading threats to native fishes. We examined how the construction of the Panama Canal, which formed Lake Gatun, and the subsequent invasion of the predatory Cichla monoculus influenced the morphology of two native fishes: Astyanax ruberrimus and Roeboides spp. Using a 100-year time series, we studied variation in overall body shape over time (before vs. after impoundment and invasion) as well as across space (between an invaded and an uninvaded reservoir). In addition, we examined variation in linear morphological traits associated with swim performance and predator detection/avoidance. Notwithstanding a few significant changes in particular traits in particular comparisons, we found only limited evidence for morphological change associated with these two stressors. Most observed changes were subtle, and tended to be site- and species-specific. The lack of a strong morphological response to these stressors, coupled with dramatic population declines in both species, suggests they may be maladapted to the anthropogenically perturbed environment of Lake Gatun, but direct measures of fitness would be needed to test this. In general, our results suggest that morphological responses to anthropogenic disturbances can be very limited and, when they do occur, are often complex and context-dependent.

RevDate: 2019-08-16

Gering E, Incorvaia D, Henriksen R, et al (2019)

Maladaptation in feral and domesticated animals.

Evolutionary applications, 12(7):1274-1286 pii:EVA12784.

Selection regimes and population structures can be powerfully changed by domestication and feralization, and these changes can modulate animal fitness in both captive and natural environments. In this review, we synthesize recent studies of these two processes and consider their impacts on organismal and population fitness. Domestication and feralization offer multiple windows into the forms and mechanisms of maladaptation. Firstly, domestic and feral organisms that exhibit suboptimal traits or fitness allow us to identify their underlying causes within tractable research systems. This has facilitated significant progress in our general understandings of genotype-phenotype relationships, fitness trade-offs, and the roles of population structure and artificial selection in shaping domestic and formerly domestic organisms. Additionally, feralization of artificially selected gene variants and organisms can reveal or produce maladaptation in other inhabitants of an invaded biotic community. In these instances, feral animals often show similar fitness advantages to other invasive species, but they are also unique in their capacities to modify natural ecosystems through introductions of artificially selected traits. We conclude with a brief consideration of how emerging technologies such as genome editing could change the tempos, trajectories, and ecological consequences of both domestication and feralization. In addition to providing basic evolutionary insights, our growing understanding of mechanisms through which artificial selection can modulate fitness has diverse and important applications-from enhancing the welfare, sustainability, and efficiency of agroindustry, to mitigating biotic invasions.

RevDate: 2019-08-15

Pazmiño-Palomino A, Mendoza J, GA Brito-Vera (2019)

First Record of Invasive Tawny Crazy Ant Nylanderia fulva (Mayr) (Hymenoptera: Formicidae) in Continental Ecuador and Notes on Its Ecology in Sugarcane Crops.

Neotropical entomology pii:10.1007/s13744-019-00709-1 [Epub ahead of print].

We report the first known record of the tawny crazy ant Nylanderia fulva (Mayr) in continental Ecuador. In addition, we describe the mutualistic association between ants and white aphids Melanaphis sacchari (Zehntner) in a sugarcane crop. Finally, we highlight the necessity to carry out studies of this nature due to an increasing number of invasive ant species in Ecuador and their potential damage to agricultural and natural ecosystems.

RevDate: 2019-08-14

Dennert F, Meyer JB, Rigling D, et al (2019)

Assessing the phytosanitary risk posed by an intraspecific invasion of Cryphonectria parasitica in Europe.

Phytopathology [Epub ahead of print].

Intraspecific cryptic invasions may occur when new strains of an invasive species are introduced into an area where this species had already been introduced previously. In plant pathogens, such invasions are not well studied, even if potentially they can have severe consequences. Here, we investigated the effects of a potential intraspecific invasion in Europe of Cryphonectria parasitica, the causal agent of chestnut blight. Specifically, we tested the hypotheses that (1) non-European strains are more virulent on Castanea sativa than those already present in Europe because they have never encountered this new host, and (2) the variation in virulence among strains is higher within native than within introduced populations. In a greenhouse, two-year old C. sativa seedlings were inoculated with C. parasitica strains from South Korea, the USA and Switzerland and lesion development and seedling mortality weekly recorded. Additionally, growth and sporulation of the strains were measured in vitro on agar medium at 15 and 24 °C. While lesion growth was similar for all strains, seedlings inoculated with strains from South Korea and Switzerland died faster than seedlings inoculated with strains from the USA. Moreover, in vitro strains from South Korea grew faster and produced more spores at both temperatures than the strains from the other two countries. In conclusion, our results did not support the two hypotheses. All strains, regardless of their origin, were found to be highly virulent on the inoculated chestnut seedlings. Nevertheless, current phytosanitary measures to avoid the introduction of new genotypes of C. parasitica into Europe should be further implemented.

RevDate: 2019-08-14

Pimsler ML, Sze SH, Saenz S, et al (2019)

Gene expression correlates of facultative predation in the blow fly Chrysomya rufifacies (Diptera: Calliphoridae).

Ecology and evolution, 9(15):8690-8701 pii:ECE35413.

Effects of intraguild predation (IGP) on omnivores and detritivores are relatively understudied when compared to work on predator guilds. Functional genetic work in IGP is even more limited, but its application can help answer a range of questions related to ultimate and proximate causes of this behavior. Here, we integrate behavioral assays and transcriptomic analysis of facultative predation in a blow fly (Diptera: Calliphoridae) to evaluate the prevalence, effect, and correlated gene expression of facultative predation by the invasive species Chrysomya rufifacies. Field work observing donated human cadavers indicated facultative predation by C. rufifacies on the native blow fly Cochliomyia macellaria was rare under undisturbed conditions, owing in part to spatial segregation between species. Laboratory assays under conditions of starvation showed predation had a direct fitness benefit (i.e., survival) to the predator. As a genome is not available for C. rufifacies, a de novo transcriptome was developed and annotated using sequence similarity to Drosophila melanogaster. Under a variety of assembly parameters, several genes were identified as being differentially expressed between predators and nonpredators of this species, including genes involved in cell-to-cell signaling, osmotic regulation, starvation responses, and dopamine regulation. Results of this work were integrated to develop a model of the processes and genetic regulation controlling facultative predation.

RevDate: 2019-08-14

Muha TP, Skukan R, Borrell YJ, et al (2019)

Contrasting seasonal and spatial distribution of native and invasive Codium seaweed revealed by targeting species-specific eDNA.

Ecology and evolution, 9(15):8567-8579 pii:ECE35379.

Aim: Codium fragile, an invasive seaweed, has spread widely during the last century, impacting on local seaweed communities through competition and disturbance. Early detection of C. fragile can help on its control and management. Environmental DNA (eDNA) has proved successful for early detection of aquatic invasive species but its potential use for seaweed remains understudied. We used a species-specific eDNA qPCR approach to investigate the spatial distribution, abundance, and coexistence of the invasive C. fragile and three native Codium species (Codium vermilara, Codium tomentosum, and Codium decorticatum) in the Cantabrian Sea.

Location: Bay of Biscay, Northern Atlantic Coast of the Iberian Peninsula; two ports, a beach and a rocky cliff.

Methods: We designed species-specific primers in barcoding regions targeting short fragments of the rbcL gene for the invasive Codium species, and the elongation factor Tu (tufA) gene for the native species, to assess their spatial and seasonal distributions using quantitative real-time PCR in samples collected during summer, autumn, and winter.

Results: We found seasonal differences in the presence of the invasive Codium fragile and two of the native Codium species, but did not detect C. decorticatum at any point. Species distribution patterns produced with qPCR targeting species-specific eDNA coincided with the known distribution based on previous conventional sampling, with a seasonal alternance of C. fragile and C. vermilara, and a marked dominance of invasive C. fragile in ports, which are known hotspots for invasive species.

Main conclusions: Our results demonstrate the utility of using eDNA for early detection and monitoring of invasive seaweed. Native and invasive Codium spp. displayed significant seasonal and spatial differentiation that needs to be taken into account in risk management. Regular monitoring of ports and adjacent areas using eDNA should help to assess the potential expansion of invasive Codium and the need for management interventions to avoid the displacement of native seaweed.

RevDate: 2019-08-13

Shang L, Hu Z, Deng Y, et al (2019)

Metagenomic Sequencing Identifies Highly Diverse Assemblages of Dinoflagellate Cysts in Sediments from Ships' Ballast Tanks.

Microorganisms, 7(8): pii:microorganisms7080250.

Ships' ballast tanks have long been known as vectors for the introduction of organisms. We applied next-generation sequencing to detect dinoflagellates (mainly as cysts) in 32 ballast tank sediments collected during 2001-2003 from ships entering the Great Lakes or Chesapeake Bay and subsequently archived. Seventy-three dinoflagellates were fully identified to species level by this metagenomic approach and single-cell polymerase chain reaction (PCR)-based sequencing, including 19 toxic species, 36 harmful algal bloom (HAB) forming species, 22 previously unreported as producing cysts, and 55 reported from ballast tank sediments for the first time (including 13 freshwater species), plus 545 operational taxonomic units (OTUs) not fully identified due to a lack of reference sequences, indicating tank sediments are repositories of many previously undocumented taxa. Analyses indicated great heterogeneity of species composition among samples from different sources. Light and scanning electron microscopy and single-cell PCR sequencing supported and confirmed results of the metagenomic approach. This study increases the number of fully identified dinoflagellate species from ballast tank sediments to 142 (> 50% increase). From the perspective of ballast water management, the high diversity and spatiotemporal heterogeneity of dinoflagellates in ballast tanks argues for continuing research and stringent adherence to procedures intended to prevent unintended introduction of non-indigenous toxic and HAB-forming species.

RevDate: 2019-08-12
CmpDate: 2019-08-12

Neilly H, L Schwarzkopf (2017)

The response of an arboreal mammal to livestock grazing is habitat dependant.

Scientific reports, 7(1):17382.

Inappropriate livestock grazing is implicated in the decline of vertebrate fauna species globally. Faunal responses to grazing can interact with the vegetation community in which they occur. We measured the response of an arboreal marsupial, the common brushtail possum (Trichosurus vulpecula vulpecula) to different cattle grazing strategies and vegetation types, and examined whether micro-habitat selection is driving this response. We hypothesised that where arboreal habitat is intact, brushtail possums would be resistant to the impacts of heavy grazing. We conducted a mark-recapture survey among four grazing treatments and in two vegetation types (Box and Ironbark), at a 20-year grazing trial in northern Australia. We found that brushtail possums were resistant to the impact of heavy grazing in both vegetation types, but preferred the heavy grazing treatment in the Box vegetation type. Complex arboreal habitat and low ground cover was preferred, and high grass cover and low tree species richness avoided. Most individuals exclusively used one vegetation type, with few using both, suggesting a 'matrix' vegetation between the Box and Ironbark may be creating a movement barrier. Vegetation type should provide a context for determining the benefits to arboreal wildlife of adopting a particular grazing management strategy.

RevDate: 2019-08-10

Auffret AG, CD Thomas (2019)

Synergistic and antagonistic effects of land use and non-native species on community responses to climate change.

Global change biology [Epub ahead of print].

Climate change, land-use change and introductions of non-native species are key determinants of biodiversity change worldwide. However, the extent to which anthropogenic drivers of environmental change interact to affect biological communities is largely unknown, especially over longer time periods. Here, we show that plant community composition in 996 Swedish landscapes has consistently shifted to reflect the warmer and wetter climate that the region has experienced during the second half of the 20th century. Using community climatic indices, which reflect the average climatic associations of the species within each landscape at each time period, we found that species compositions in 74% of landscapes now have a higher representation of warm-associated species than they did previously, while 84% of landscapes now host more species associated with higher levels of precipitation. In addition to a warmer and wetter climate, there have also been large shifts in land use across the region, while the fraction of non-native species has increased in the majority of landscapes. Climatic warming at the landscape level appeared to favour the colonization of warm-associated species, while also potentially driving losses in cool-associated species. However, the resulting increases in community thermal means were apparently buffered by landscape simplification (reduction in habitat heterogeneity within landscapes) in the form of increased forest cover. Increases in non-native species, which generally originate from warmer climates than Sweden, were a strong driver of community-level warming. In terms of precipitation, both landscape simplification and increases in non-natives appeared to favour species associated with drier climatic conditions, to some extent counteracting the climate-driven shift towards wetter communities. Anthropogenic drivers can act both synergistically and antagonistically to determine trajectories of change in biological communities over time. Therefore, it is important to consider multiple drivers of global change when trying to understand, manage and predict biodiversity in the future.

RevDate: 2019-08-10

Zhao Z, Hui C, Plant RE, et al (2019)

The failure of success: Cyclic recurrences of a globally invasive pest.

Ecological applications : a publication of the Ecological Society of America [Epub ahead of print].

For the past six decades since 1960 the oriental fruit fly, Bactrocera dorsalis (Hendel), has been announced successfully eradicated in California by the US Department of Agriculture for a total of 564 times. This includes eradication declarations in 1 city a total of 25 different years, in 12 cities 8 to 19 different years, and in 101 cities 2 to 7 different years. We here show that the false negatives in declaring elimination success hinge on the easily-achieved regulatory criteria, which have virtually guaranteed the failure of complete extirpation of this pest. Analyses of the time series of fly detection over California gridded into 100 km2 cells revealed, (1) partial success of eradication program in controlling the invasion of the oriental fruit fly; (2) low prevalence of the initial detection in these cells is often followed by high prevalence of recurrences; (3) progressively shorter intervals between years of consecutive detections; and (4) high likelihood of early-infested cells also experiencing the most frequent outbreaks. Facing the risk of recurrent invasions, such short-term eradication programs have only succeeded annually according to the current regulatory criteria but have failed to achieve the larger goal of complete extirpation of the oriental fruit fly. Based on the components and running costs of the current programs, we further estimated the efficiency of eradication programs with different combinations of eradication radius, duration, and edge impermeability in reducing invasion recurrences and slowing the spread of the oriental fruit fly. We end with policy implications including the need for agricultural agencies worldwide to revisit eradication protocols in which monitoring and treatments are terminated when the regulatory criteria for declaring eradication are met. Our results also have direct implications to invasion biologists and agriculture policy makers regarding long-term risks of short-term expediency. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-10

Suckling DM, Stringer LD, Baird DB, et al (2019)

Will growing invasive arthropod biodiversity outpace our ability for eradication?.

Ecological applications : a publication of the Ecological Society of America [Epub ahead of print].

The Global Eradication Database (http://b3.net.nz/gerda) documents 811 eradication attempts against invasive arthropods since 1890, in 104 countries. Eradication programs show a greater than exponential increase in the number of programs started in recent decades. In addition, there is a trend of a rapidly diversifying burden of the most severe threats. The species richness showed a three-fold increase in number of species under eradication in the last 50 years, and all taxonomic levels rose dramatically. The increase in number of eradication programs shows that current management measures for constraining the spread of invasive species are inadequate. A similar surge in the number of governments trying to prevent the establishment of new pests has occurred. Increased biodiversity of arthropod eradication targets includes new pest groups with fewer tools developed for management. We argue that a rapid increase in biodiversity of invasive and economically or environmentally damaging organisms represents a substantial and underestimated challenge for managers wanting to prevent their establishment, requiring a shift in research focus to accelerate delimitation and suppression options with less reliance on insecticides. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-10

Puckett EE, Magnussen E, Khlyap LA, et al (2019)

Genomic analyses reveal three independent introductions of the invasive brown rat (Rattus norvegicus) to the Faroe Islands.

Heredity pii:10.1038/s41437-019-0255-6 [Epub ahead of print].

Population genomics offers innovative approaches to test hypotheses related to the source and timing of introduction of invasive species. These approaches are particularly appropriate to study colonization of island ecosystems. The brown rat is a cold-hardy global invasive that has reached most of the world's island ecosystems, including even highly isolated archipelagoes such as the Faroe Islands in the North Atlantic Ocean. Historic records tell of rats rafting to the southern island of Suðuroy in 1768 following a shipwreck off the coast of Scotland, then expanding across the archipelago. We investigated the demographic history of brown rats in the Faroes using 50,174 SNPs. We inferred three independent introductions of rats, including to Suðuroy, the islands of Borðoy and Viðoy, and onto Streymoy from which they expanded to Eysturoy and Vágar. All Faroese populations showed signs of strong bottlenecks and declining effective population size. We inferred that these founder events removed low frequency alleles, the exact data needed to estimate recent demographic histories. Therefore, we were unable to accurately estimate the timing of each invasion. The difficulties with demographic inference may be applicable to other invasive species, particularly those with extreme and recent bottlenecks. We identified three invasions of brown rats to the Faroe Islands that resulted in highly differentiated populations that will be useful for future studies of life history variation and genomic adaptation.

RevDate: 2019-08-10

Holman LE, de Bruyn M, Creer S, et al (2019)

Detection of introduced and resident marine species using environmental DNA metabarcoding of sediment and water.

Scientific reports, 9(1):11559 pii:10.1038/s41598-019-47899-7.

Environmental DNA (eDNA) surveys are increasingly being used for biodiversity monitoring, principally because they are sensitive and can provide high resolution community composition data. Despite considerable progress in recent years, eDNA studies examining how different environmental sample types can affect species detectability remain rare. Comparisons of environmental samples are especially important for providing best practice guidance on early detection and subsequent mitigation of non-indigenous species. Here we used eDNA metabarcoding of COI (cytochrome c oxidase subunit I) and 18S (nuclear small subunit ribosomal DNA) genes to compare community composition between sediment and water samples in artificial coastal sites across the United Kingdom. We first detected markedly different communities and a consistently greater number of distinct operational taxonomic units in sediment compared to water. We then compared our eDNA datasets with previously published rapid assessment biodiversity surveys and found excellent concordance among the different survey techniques. Finally, our eDNA surveys detected many non-indigenous species, including several newly introduced species, highlighting the utility of eDNA metabarcoding for both early detection and temporal / spatial monitoring of non-indigenous species. We conclude that careful consideration on environmental sample type is needed when conducting eDNA surveys, especially for studies assessing community change.

RevDate: 2019-08-09

Petri B, Chaganti SR, Chan PS, et al (2019)

Phytoplankton growth characterization in short term MPN culture assays using 18S metabarcoding and qRT-PCR.

Water research, 164:114941 pii:S0043-1354(19)30715-8 [Epub ahead of print].

The most probable number dilution-culture assay (MPN) is used to enumerate viable phytoplankton in regulatory tests of ballast water treatment systems. However the United States Coast Guard has not yet accepted MPN, in part due to concerns of biased results due to cells being viable but not growing. MPN does not assess the fate of every cell, and thus the bias can only be evaluated by a companion method that assesses the ability of the various taxa to grow. This growth ability ("growability") is the complement of the bias, and has been evaluated by microscopic taxonomy of before-culture and after-culture samples. However, microscopic taxonomy is extremely laborious and few data have been produced for phytoplankton growability in MPN assays. To address the need for more and more reliable growability data, a method was developed using next-generation sequencing (NGS) and quantitative real time PCR (qRT-PCR) techniques that target the V9 region of the 18S rRNA gene for the taxonomic identification and growth assessment of eukaryotic phytoplankton, respectively. This growability method was applied to MPN samples from a ballast water management system test that were incubated with two different enrichment media at two different temperatures. DNA was extracted from filters of before-culture and after-culture samples, and assessed for taxonomy by NGS and for PCR template DNA concentration by qRT-PCR. Growth ratios based on changes in 18S template concentration over the incubation period were calculated for each taxon, and dead-cell DNA persistence through a 14 day incubation was verified to be <1% and did not influence the growth calculations. In total, 95 of 97 eukaryotic phytoplankton in the before-culture sample demonstrated growth, with definitive growth ratios ranging from 4.0 × 101-2.6 × 105. An additional 13 taxa demonstrated growth from non-detect in before-culture samples. Taxa-based growability values were 87-88% in individual incubation conditions with no statistical differences among conditions, and 98% for all conditions combined. When growability was weighted by the before-culture abundance of each taxa, relevant to regulations based on all organisms regardless of taxa, community-based growability was >99% in each condition and in all conditions combined because the most abundant taxa all exhibited growth. This study verifies that conventional phytoplankton MPN assays produce accurate results with low bias from undetected viable cells, regardless of enrichments and incubation temperatures. This work can provide regulatory confidence for broader acceptance of MPN assays without limitations.

RevDate: 2019-08-09

Bortolus A, Adam P, Adams JB, et al (2019)

Supporting Spartina: Interdisciplinary perspective shows Spartina as a distinct solid genus.

Ecology [Epub ahead of print].

In 2014 a DNA-based phylogenetic study confirming the paraphyly of the grass subtribe Sporobolinae proposed the creation of a large monophyletic genus Sporobolus, including (among others) species previously included in the genera Spartina, Calamovilfa, and Sporobolus. Spartina species have contributed substantially (and continue contributing) to our knowledge in multiple disciplines, including ecology, evolutionary biology, molecular biology, biogeography, experimental ecology, biological invasions, environmental management, restoration ecology, history, economics, and sociology. There is no rationale so compelling to subsume the name Spartina as a subgenus that could rival the striking, global iconic history and use of the name Spartina for over 200 years. We do not agree with the subjective arguments underlying the proposal to change Spartina to Sporobolus. We understand the importance of both the objective phylogenetic insights and of the subjective formalized nomenclature and hope that by opening this debate we will encourage positive feedback that will strengthen taxonomic decisions with an interdisciplinary perspective. We consider that the strongly distinct, monophyletic clade Spartina should simply and efficiently be treated as the genus Spartina. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-09

Moreno Salas L, Espinoza-Carniglia M, Lizama Schmeisser N, et al (2019)

Fleas of black rats (Rattus rattus) as reservoir host of Bartonella spp. in Chile.

PeerJ, 7:e7371 pii:7371.

Background: Rattus rattus is a widely distributed, invasive species that presents an important role in disease transmission, either directly or through vector arthropods such as fleas. These black rats can transmit a wide variety of pathogens, including bacteria of the genus Bartonella, which can cause diseases in humans and animals. In Chile, no data are available identifying fleas from synanthropic rodents as Bartonella vectors. The aim of this study was to investigate the prevalence of Bartonella spp. in the fleas of R. rattus in areas with different climate conditions and featuring different human population densities.

Methods: In all, 174 fleas collected from 261 R. rattus captured from 30 localities with different human densities (cities, villages, and wild areas) across five hydrographic zones of Chile (hyper-arid, arid, semi-arid, sub-humid, and hyper-humid) were examined. Bartonella spp. presence was determined through polymerase chain reaction, using gltA and rpoB genes, which were concatenated to perform a similarity analysis with BLAST and phylogenetic analysis.

Results: Overall, 15 fleas species were identified; Bartonella gltA and rpoB fragments were detected in 21.2% (37/174) and 19.5% (34/174) of fleas, respectively. A total of 10 of the 15 fleas species found were positive for Bartonella DNA. Leptopsylla segnis was the most commonly collected flea species (n = 55), and it also presented a high prevalence of Bartonella DNA (P% = 34.5%). The highest numbers of fleas of this species were collected in villages of the arid zone. There were no seasonal differences in the prevalence of Bartonella DNA. The presence of Bartonella DNA in fleas was recorded in all hydrographic areas, and the arid zone presented the highest prevalence of this species. Regarding areas with different human densities, the highest prevalence was noted in the villages (34.8% gltA and 31.8% rpoB), followed by cities (14.8% gltA and 11.1% rpoB) and wild areas (7.4% gltA and 14.8% rpoB). The BLAST analysis showed a high similitude (>96%) with four uncharacterized Bartonella genotypes and with two species with zoonotic potential: B. mastomydis and B. tribocorum. The phylogenetic analysis showed a close relationship with B. elizabethae and B. tribocorum. This is the first study to provide evidence of the presence of Bartonella in fleas of R. rattus in Chile, indicating that the villages and arid zone correspond to areas with higher infection risk.

RevDate: 2019-08-08

Shabani F, Nasrolahi A, M Thiel (2019)

Assemblage of encrusting organisms on floating anthropogenic debris along the northern coast of the Persian Gulf.

Environmental pollution (Barking, Essex : 1987), 254(Pt A):112979 pii:S0269-7491(19)31540-4 [Epub ahead of print].

Global concern about floating marine debris and its fundamental role in shaping coastal biodiversity is growing, yet there is very little knowledge about debris-associated rafting communities in many areas of the world's oceans. In the present study, we examined the encrusting assemblage on different types of stranded debris (wood, plastic, glass, and metal cans) along the Iranian coast of the Persian Gulf. In total, 21 taxa were identified on 132 items. The average frequency of occurrence (±SE) across all sites and stranded debris showed that the barnacle Amphibalanus amphitrite (68.9 ± 1.1%), the oyster Saccostrea cucullata (40.9 ± 0.7%), the polychaete Spirobranchus kraussii (27.3 ± 0.5%), green algae (22 ± 0.5%) and the coral Paracyathus stokesii (14.4 ± 0.7%) occurred most frequently. Relative substratum coverage was highest for A. amphitrite (44.3 ± 2.7%), followed by green algae (14.4 ± 1.5%), Spirobranchus kraussii (9.3 ± 1.3%), Saccostrea cucullata (7.6 ± 1.3%) and the barnacle Microeuraphia permitini (5.8 ± 0.9%). Despite the significant difference in coverage of rafting species on plastic items among different sites, there was no clear and consistent trend of species richness and coverage from the eastern (Strait of Hormuz) to the western part of the Persian Gulf. Some rafting species (bryozoans and likely barnacles) were found to be non-indigenous species in the area. As floating marine debris can transport non-indigenous species and increase the risk of bio-invasions to this already naturally- and anthropogenically-stressed water body, comprehensive monitoring efforts should be made to elucidate the vectors and arrival of new invasive species to the region.

RevDate: 2019-08-08

Hintz WD, Schuler MS, Jones DK, et al (2019)

Nutrients influence the multi-trophic impacts of an invasive species unaffected by native competitors or predators.

The Science of the total environment, 694:133704 pii:S0048-9697(19)33642-3 [Epub ahead of print].

Non-native species often lead to undesirable ecological and environmental impacts. Two hypotheses that predict establishment of non-native species are enemy release and biotic resistance. Support for these hypotheses in freshwater invasions is mixed. Experiments combined with field observations provide a complementary approach to understanding how interactions between native and non-native species lead to enemy release or biotic resistance. We tested experimentally whether these hypotheses provided insights into the invasion of the banded mystery snail (Viviparus georgianus), which has invaded the Great Lakes region and northeastern Unites States (US) from the southeastern US. Because freshwater systems vary widely in their nutrient concentrations due to natural and anthropogenic processes, we tested whether nutrient additions altered competitive and predatory interactions that regulate mechanisms of enemy release or biotic resistance. We evaluated the status of the mystery snail invasion in a 3-year field survey of Lake George (NY, US) to identify if field observations supported any experimental conclusions. The presence of the banded mystery snail led to a 14% and 27% reduction in biomass of a native competitor under low- and high-nutrient concentrations, respectively. The mystery snail also triggered a 29% biomass loss of a native snail predator, but only in low-nutrient concentrations. Field surveys indicated that the mystery snail dominated the snail community; of seven snail species, it comprised 77% of all snails. Results from the field surveys combined with experimental results indicate that neither competitors nor predators have likely suppressed the invasion of the banded mystery snail. This conclusion is consistent with competitive- and predatory-enemy release as we found no indication of biotic resistance via competition or predation from native species. Our results further highlight that the post-establishment impacts of invasive species are altered by the trophic state of freshwater ecosystems.

RevDate: 2019-08-08

Cornelissen B, Neumann P, O Schweiger (2019)

Global warming promotes biological invasion of a honey bee pest.

Global change biology [Epub ahead of print].

Climate change and biological invasions are two major global environmental challenges. Both may interact, e.g. via altered impact and distribution of invasive alien species. Even though invasive species play a key role for compromising the health of honey bees, the impact of climate change on the severity of such species is still unknown. The small hive beetle (SHB, Aethina tumida, Murray) is a parasite of honey bee colonies. It is endemic to Sub-Saharan Africa and has established populations on all continents except Antarctica. Since SHBs pupate in soil, pupation performance is governed foremost by two abiotic factors, soil temperature and moisture, which will be affected by climate change. Here, we investigated SHB invasion risk globally under current and future climate scenarios. We modelled survival and development time during pupation (= pupal performance) in response to soil temperature and soil moisture using published and novel experimental data. Presence data on SHB distribution were used for model validation. We then linked the model with global soil data in order to classify areas (resolution: 10 arcmin; i.e. 18.6 km at the equator) as unsuitable, marginal and suitable for SHB pupation performance. Under the current climate, the results show that many areas globally yet uninvaded are actually suitable, suggesting considerable SHB invasion risk. Future scenarios of global warming project a vehement increase in climatic suitability for SHB and corresponding potential for invasion, especially in the temperate regions of the Northern hemisphere, thereby creating demand for enhanced and adapted mitigation and management. Our analysis shows, for the first time, effects of global warming on a honey bee pest and will help areas at risk to prepare adequately. In conclusion, this is a clear case for global warming promoting biological invasion of a pest species with severe potential to harm important pollinator species globally. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-08

Milnes JM, EH Beers (2019)

Trissolcus japonicus (Hymenoptera: Scelionidae) Causes Low Levels of Parasitism in Three North American Pentatomids Under Field Conditions.

Journal of insect science (Online), 19(4):.

Trissolcus japonicus (Ashmead), an Asian parasitoid of Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), was first detected in North America in 2014. Although testing in quarantine facilities as a candidate for classical biological control is ongoing, adventive populations have appeared in multiple sites in the United States, Canada, and Europe. Extensive laboratory testing of T. japonicus against other North American pentatomids and H. halys has revealed a higher rate of parasitism of H. halys, but not complete host specificity. However, laboratory tests are necessarily artificial, in which many host finding and acceptance cues may be circumvented. We offered sentinel egg masses of three native pentatomid (Hemiptera: Pentatomidae) pest species (Chinavia hilaris (Say), Euschistus conspersus Uhler, and Chlorochroa ligata (Say)) in a field paired-host assay in an area with a well-established adventive population of T. japonicus near Vancouver, WA. Overall, 67% of the H. halys egg masses were parasitized by T. japonicus during the 2-yr study. Despite the 'worst case' scenario for a field test (close proximity of the paired egg masses), the rate of parasitism (% eggs producing adult wasps) on all three native species was significantly less (0.4-8%) than that on H. halys eggs (77%). The levels of successful parasitism of T. japonicus of the three species are C. hilaris > E. conspersus > C. ligata. The potential impact of T. japonicus on these pentatomids is probably minimal.

RevDate: 2019-08-08

Martín-Torrijos L, Kokko H, Makkonen J, et al (2019)

Mapping 15 years of crayfish plague in the Iberian Peninsula: The impact of two invasive species on the endangered native crayfish.

PloS one, 14(8):e0219223 pii:PONE-D-19-13318.

Crayfish plague, caused by the pathogen Aphanomyces astaci, is one of the main factors responsible for the decimation of the native European crayfish species Austropotamobius pallipes. In Spain, two North American freshwater crayfish species, Procambarus clarkii and Pacifastacus leniusculus, were intentionally introduced during the 1970s for aquaculture and fishery purposes. Since then, incidences of crayfish plague have been continually reported. In this work, we evaluated more than 50 diagnosed cases of crayfish plague that have occurred in the Iberian Peninsula since 2004 by performing a microscopic examination of infected specimens and by molecularly identifying and haplotyping the pathogen. Our results showed that (i) the pathogen A. astaci has been active 45 years since the first introductions of the invasive North American crayfish species in the Iberian Peninsula, and (ii) P. clarkii and P. leniusculus are chronic reservoirs of the crayfish plague pathogen. Moreover, our data confirmed a correspondence between pathogen origin and spread and the specific haplotypes carried by the North American invasive crayfish located in the vicinity of each outbreak. We generated a crayfish plague incidence map of the Iberian Peninsula that shows (i) a northern area, mainly inhabited by alien P. leniusculus, where crayfish plague cases are associated with the b-haplotype specific to P. leniusculus, and (ii) southern, central and eastern areas that are basically inhabited by alien P. clarkii, where crayfish plague cases are associated with the d1- and d2-haplotypes specific to P. clarkii. The results presented here are evidence of the long standing and negative impact of the two invasive crayfish species on the native species, indicating the need for more extensive control measures.

RevDate: 2019-08-08

DeBellis T, Kembel SW, JP Lessard (2019)

Shared mycorrhizae but distinct communities of other root-associated microbes on co-occurring native and invasive maples.

PeerJ, 7:e7295 pii:7295.

Background: Biological invasions are major drivers of environmental change that can significantly alter ecosystem function and diversity. In plants, soil microbes play an important role in plant establishment and growth; however, relatively little is known about the role they might play in biological invasions. A first step to assess whether root microbes may be playing a role in the invasion process is to find out if invasive plants host different microbes than neighbouring native plant species.

Methods: In this study we investigated differences in root associated microbes of native sugar maple (Acer saccharum Marsh.) and exotic Norway maple (A. platanoides L.) collected from a forested reserve in eastern Canada. We used microscopy to examine root fungi and high-throughput sequencing to characterize the bacterial, fungal and arbuscular mycorrhizal communities of both maple species over one growing season.

Results: We found differences in root associated bacterial and fungal communities between host species. Norway maple had a higher bacterial and fungal OTU (operational taxonomic units) richness compared to sugar maple, and the indicator species analysis revealed that nine fungal OTUs and three bacterial OTUs had a significant preference for sugar maple. The dominant bacterial phyla found on the roots of both maple species were Actinobacteria and Proteobacteria. The most common fungal orders associated with the Norway maple roots (in descending order) were Helotiales, Agaricales, Pleosporales, Hypocreales, Trechisporales while the Agaricales, Pleosporales, Helotiales, Capnodiales and Hypocreales were the dominant orders present in the sugar maple roots. Dark septate fungi colonization levels were higher in the sugar maple, but no differences in arbuscular mycorrhizal fungal communities and colonization rates were detected between maple species.

Discussion: Our findings show that two congeneric plant species grown in close proximity can harbor distinct root microbial communities. These findings provide further support for the importance of plant species in structuring root associated microbe communities. The high colonization levels observed in Norway maple demonstrates its compatibility with arbuscular mycorrhizal fungi in the introduced range. Plant-associated microbial communities can affect host fitness and function in many ways; therefore, the observed differences suggest a possibility that biotic interactions can influence the dynamics between native and invasive species.

RevDate: 2019-08-08

Heuring C, Barber D, Rains N, et al (2019)

Genetics, morphology and diet of introduced populations of the ant-eating Texas Horned Lizard (Phrynosoma cornutum).

Scientific reports, 9(1):11470 pii:10.1038/s41598-019-47856-4.

Introduced species can diverge from their source population when they become established in a new ecosystem. The Texas Horned Lizard (Phrynosoma cornutum) is native to the western United States (US) and was historically introduced to several locations in the southeastern US. We studied three introduced populations in South Carolina, US to determine if they exhibit dietary, morphological and genetic divergence from the native western US populations. We expected little divergence from western populations because P. cornutum is a specialist whose biology is largely shaped by its diet of Pogonomyrmex harvester ants. We show that the introduced populations have mixed ancestry between south Texas and more northern areas and experienced founder effects and genetic bottlenecks resulting in decreased genetic diversity. South Carolina lizards primarily consume ants (94%), but surprisingly, they did not eat harvester ants. Introduced lizards primarily eat Dorymyrmex ants, but each introduced population complements Dorymyrmex with significantly different amounts of other species of ants, insects and plant matter. Introduced populations have smaller body size and have different limb and head shapes compared to western populations. This study demonstrates successful persistence of an introduced vertebrate that may be attributed to phenotypic change, even in the face of reduced genetic diversity.

RevDate: 2019-08-07

Ramírez-Pizarro F, Silva-de la Fuente C, Hernández-Orellana C, et al (2019)

Zoonotic Pathogens in the American Mink in Its Southernmost Distribution.

Vector borne and zoonotic diseases (Larchmont, N.Y.) [Epub ahead of print].

The American mink, Neovison vison, is an invasive species in Chile. Its impact on native fauna and public health has not been studied in depth in the country. In this study, we searched for gastrointestinal parasites, including helminths and zoonotic Cryptosporidium sp., the presence of Trichinella sp. in muscle, and the renal carriage of pathogenic Leptospira sp. in minks caught on Navarino Island, "Magallanes y la Antártica Chilena" Region, and Maullín and Ancud, "Los Lagos" Region, Chile. A total of 58, 15, and 21 minks from Navarino Island, Maullín, and Ancud, respectively, were examined for Trichinella sp. (artificial digestion of muscle). A total of 36, 11, and 17 minks from Navarino Island, Maullín, and Ancud, respectively, were examined for pathogenic Leptospira species (molecular detection of LipL32 gen fragment in renal tissue) infection. Finally, 45, 11, and 17 minks from Navarino Island, Maullín, and Ancud, respectively, were analyzed to detect gastrointestinal parasites (by optical inspection of the digestive tract for helminths, and by both Ziehl-Neelsen stain and molecular detection of small subunit-ribosomal DNA for Cryptosporidium species). Trichinella larvae were not observed. Pathogenic Leptospira sp. was detected in 22 samples: 15 from Navarino Island, 3 from Maullín, and 4 from Ancud. Two nematodes, belonging to Ascaridinae (subfamily) and Pterygodermatites (Paucipectines) sp., were found in samples of two minks from Navarino Island. Oocysts and DNA of Cryptosporidium sp. were detected in three fecal samples from Navarino Island. Further studies could determine the zoonotic potential of Cryptosporidium sp., as well as the potential impact of the zoonotic Leptospira sp. on the human population of the Navarino Island, Maullín, and Ancud districts. The enemy release theory could explain the low helminth species richness in the minks. In addition, we did not find evidence of parasite transmission from native fauna.

RevDate: 2019-08-07

Poirier MV (2019)

A trade-off model for immunocompetence: The potential contribution of immunological regulation in invasive vertebrate success.

Journal of experimental zoology. Part A, Ecological and integrative physiology [Epub ahead of print].

Invasive species have become a prolific environmental issue, second only to climate change, yet many of the phenomena that facilitate invasive success are not well understood (Phillip & Shine, Proc. Roy. Soc. B, 273, 1545-1550). The combination of several generalist life-history traits, certain physiological mechanisms, and environmental conditions is thought to play a significant role in invasion success. The ability to undergo fitness trade-offs-to reallocate nutritional and energetic resources towards processes that increase reproduction, growth, and dispersal-is also thought to be an adaptive quality of many invasive species. Due to their inherent flexibility, phenotypically plastic traits in particular are often targeted for fitness reallocations. Immune function, for example, is determined by a highly plastic phenotype, which is crucial for combating a diverse array of pathogens. When active, immune function also demands extensive resources from the host. Laboratory and field studies suggest that certain aspects of the immune system are more costly than others, though, and that its components can be regulated independent of one another. In invasive species undergoing fitness trade-offs, costly innate inflammatory responses are often downregulated, while antibody-mediated responses may be enhanced. A combination of fixed physiological responses and environmentally induced trade-offs are thought to regulate the immune system, though the relationship between these facets of regulation is still an area of active research. The field of ecoimmunology, then, has emerged in effort to understand the phenomena by which individual immune regulation can drive (and be driven by) species-level ecology and evolution, and therefore be linked to invasive success (Downs et al., 2014. Integr. Compar. Biol., 54, 340-352).

RevDate: 2019-08-07

Sadchatheeswaran S, Moloney CL, Branch GM, et al (2019)

Blender interstitial volume: A novel virtual measurement of structural complexity applicable to marine benthic habitats.

MethodsX, 6:1728-1740 pii:S2215-0161(19)30189-X.

Blender interstitial volume is a novel method that utilizes 3D modeling techniques to accurately and efficiently quantify the volume of interstitial gaps in marine benthic habitats, as well as the space provided by substrate rugosity. This method builds upon the analog methods routinely used on rocky shores and intertidal habitats, including those that measure rugosity, topography, fractals and volume. The method provides a direct Euclidean measurement and uniquely allows retrospective analysis if historical data on species composition are available. Blender interstitial volume allows users to quickly build and measure a large number of samples at no extra cost. •The program for Blender is free and opensource, and requires no extra equipment.•Once 3D models of species are made, the entire method takes less than ten minutes to complete.•Blender interstitial volume is as accurate as Fractal analysis in determining structural complexity on rocky shores, but is more consistent and precise, and better at discerning differences.

RevDate: 2019-08-07

Ahmad R, Khuroo AA, Charles B, et al (2019)

Global distribution modelling, invasion risk assessment and niche dynamics of Leucanthemum vulgare (Ox-eye Daisy) under climate change.

Scientific reports, 9(1):11395 pii:10.1038/s41598-019-47859-1.

In an era of climate change, biological invasions by alien species represent one of the main anthropogenic drivers of global environmental change. The present study, using an ensemble modelling approach, has mapped current and future global distribution of the invasive Leucanthemum vulgare (Ox-eye Daisy) and predicted the invasion hotspots under climate change. The current potential distribution of Ox-eye Daisy coincides well with the actual distribution records, thereby indicating robustness of our model. The model predicted a global increase in the suitable habitat for the potential invasion of this species under climate change. Oceania was shown to be the high-risk region to the potential invasion of this species under both current and future climate change scenarios. The results revealed niche conservatism for Australia and Northern America, but contrastingly a niche shift for Africa, Asia, Oceania and Southern America. The global distribution modelling and risk assessment of Ox-eye Daisy has immediate implications in mitigating its invasion impacts under climate change, as well as predicting the global invasion hotspots and developing region-specific invasion management strategies. Interestingly, the contrasting patterns of niche dynamics shown by this invasive plant species provide novel insights towards disentangling the different operative mechanisms underlying the process of biological invasions at the global scale.

RevDate: 2019-08-07

Ibáñez MD, MA Blázquez (2019)

Phytotoxic Effects of Commercial Eucalyptus citriodora, Lavandula angustifolia, and Pinus sylvestris Essential Oils on Weeds, Crops, and Invasive Species.

Molecules (Basel, Switzerland), 24(15): pii:molecules24152847.

BACKGROUND: essential oils are well known for their pharmacological effectiveness as well as their repellent, insecticide, and herbicide activities. The emergence of resistant weeds, due to the overuse of synthetic herbicides, makes it necessary to find natural alternatives for weed control. The aim of this study was to evaluate the phytotoxic effects of Eucalyptus citriodora, Lavandulaangustifolia, and Pinus sylvestris, three common commercial essential oils, on weeds (Portulaca oleracea, Lolium multiflorum, and Echinochloa crus-galli), food crops (tomato and cucumber), and the invasive species Nicotiana glauca. Methods: to determine herbicidal effects, essential oils were tested at different concentrations (0.125-1µL/mL). The index of germination and seedling length data were recorded over 14 days.

RESULTS: the in vitro assays showed that L. angustifolia with linalool (38.7 ± 0.1%), 1,8-cineole (26.5 ± 0.1%), and camphor (14.2 ± 0.1%) as the main compounds showed the most phytotoxic effects affecting seed germination in weeds and tomato, and the aforementioned invasive species. L. multiflorum was the most sensitive weed, particularly to lavender essential oil, which decreased the growth of its hypocotyl and radicle by 87.8% and 76.7%, respectively, at a dose of 1 µL/mL. Cucumber was the most resistant food crop, with no significant reduction observed in seed germination and hypocotyl growth with E. citriodora and L. angustifolia essential oils.

CONCLUSIONS: lavender essential oil represents a promising candidate for the development of effective and safe herbicides in the management of L. multiflorum affecting cucumber crops.

RevDate: 2019-08-07
CmpDate: 2019-08-07

Trøjelsgaard K, Heleno R, A Traveset (2019)

Native and alien flower visitors differ in partner fidelity and network integration.

Ecology letters, 22(8):1264-1273.

Globalisation persistently fuels the establishment of non-native species outside their natural ranges. While alien plants have been intensively studied, little is known about alien flower visitors, and especially, how they integrate into natural communities. Here, we focus on mutualistic networks from five Galápagos islands to quantify whether alien and native flower visitors differ consistently in their pairwise interactions. We find that (1) alien flower visitors have more interaction partners and larger species strengths (i.e. plants are more connected to alien insects), (2) native insects tend to have higher partner fidelity as they deviate more from random partner utilisation, and iii) the difference between native and alien flower visitors in network integration intensifies with island degradation. Thus, native and alien flower visitors are not interchangeable, and alien establishment might have yet unforeseen consequences for the pairwise dynamics between plants and flower visitors on the Galápagos - especially on the heavily disturbed islands.

RevDate: 2019-08-07
CmpDate: 2019-08-07

Catford JA, Smith AL, Wragg PD, et al (2019)

Traits linked with species invasiveness and community invasibility vary with time, stage and indicator of invasion in a long-term grassland experiment.

Ecology letters, 22(4):593-604.

Much uncertainty remains about traits linked with successful invasion - the establishment and spread of non-resident species into existing communities. Using a 20-year experiment, where 50 non-resident (but mostly native) grassland plant species were sown into savannah plots, we ask how traits linked with invasion depend on invasion stage (establishment, spread), indicator of invasion success (occupancy, relative abundance), time, environmental conditions, propagule rain, and traits of invaders and invaded communities. Trait data for 164 taxa showed that invader occupancy was primarily associated with traits of invaders, traits of recipient communities, and invader-community interactions. Invader abundance was more strongly associated with community traits (e.g. proportion legume) and trait differences between invaders and the most similar resident species. Annuals and invaders with high-specific leaf area were only successful early in stand development, whereas invaders with conservative carbon capture strategies persisted long-term. Our results indicate that invasion is context-dependent and long-term experiments are required to comprehensively understand invasions.

RevDate: 2019-08-06

Pereyra PJ (2019)

Rethinking the native range concept.

Conservation biology : the journal of the Society for Conservation Biology [Epub ahead of print].

A species is not native outside its native range, but native range is not precisely defined. The invasion literature contains wide discussion of the core concepts, such as naturalization, invasiveness, and ecological impact, but the concept has received so little attention that a formal definition does not exist. I considered, among other impediments to a formal definition of native range, the sometimes arbitrariness of the spatial and temporal limits assigned to native range. Broad questions that remain include whether invasion theory can be used to define the native range for species without non-native ranges. Article impact statement: A precise definition of native range is needed to properly define native species and thus apply the origin of species in conservation. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-06

Margus A, Piiroinen S, Lehmann P, et al (2019)

Sublethal Pyrethroid Insecticide Exposure Carries Positive Fitness Effects Over Generations in a Pest Insect.

Scientific reports, 9(1):11320 pii:10.1038/s41598-019-47473-1.

Stress tolerance and adaptation to stress are known to facilitate species invasions. Many invasive species are also pests and insecticides are used to control them, which could shape their overall tolerance to stress. It is well-known that heavy insecticide usage leads to selection of resistant genotypes but less is known about potential effects of mild sublethal insecticide usage. We studied whether stressful, sublethal pyrethroid insecticide exposure has within-generational and/or maternal transgenerational effects on fitness-related traits in the Colorado potato beetle (Leptinotarsa decemlineata) and whether maternal insecticide exposure affects insecticide tolerance of offspring. Sublethal insecticide stress exposure had positive within-and transgenerational effects. Insecticide-stressed larvae had higher adult survival and higher adult body mass than those not exposed to stress. Furthermore, offspring whose mothers were exposed to insecticide stress had higher larval and pupal survival and were heavier as adults (only females) than those descending from control mothers. Maternal insecticide stress did not explain differences in lipid content of the offspring. To conclude, stressful insecticide exposure has positive transgenerational fitness effects in the offspring. Therefore, unsuccessful insecticide control of invasive pest species may lead to undesired side effects since survival and higher body mass are known to facilitate population growth and invasion success.

RevDate: 2019-08-06

Feás Sánchez X, RJ Charles (2019)

Notes on the Nest Architecture and Colony Composition in Winter of the Yellow-Legged Asian Hornet, Vespa velutina Lepeletier 1836 (Hym.: Vespidae), in Its Introduced Habitat in Galicia (NW Spain).

Insects, 10(8): pii:insects10080237.

Fifteen years ago, at least one multimated female yellow-legged Asian hornet (Vespa velutina Lepeletier 1836) arrived in France, giving rise to a pan-European invasion, altering the environment, affecting ecosystem processes, and impacting society. During winter, V. velutina nests (n = 3) were collected in Galicia and data on internal and external aspects of the nests and the colony as a whole were collected. The whole colony population (WCPN; adult insects, larvae, and pupae in percentages) was as follows: nest A: n = 176 (49%, 3%, and 48%); nest B: n = 1979 (52%, 36%, and 12%); and nest C: n = 662 (5%, 27%, and 8%). The adult insect population (IAPN; males, workers, and gynes in percentages) was as follows: nest A: n = 87 (11%, 66%, and 23%); nest B: n = 1021 (3%, 62%, and 35%); and nest C: n = 430 (20%, 73%, and 7%). As a small number of queens is sufficient for a population to develop, it is necessary to avoid continued spread by deactivating and removing all nests, even those detected in winter. This practice can be of greatest importance in border areas where V. velutina is expanding into new territory.

RevDate: 2019-08-06

Peng Z, Bhattarai K, Parajuli S, et al (2019)

Transcriptome Analysis of Young Ovaries Reveals Candidate Genes Involved in Gamete Formation in Lantana camara.

Plants (Basel, Switzerland), 8(8): pii:plants8080263.

Lantana (Lantana camara L., Verbenaceae) is an important ornamental crop, yet can be a highly invasive species. The formation of unreduced female gametes (UFGs) is a major factor contributing to its invasiveness and has severely hindered the development of sterile cultivars. To enrich the genomic resources and gain insight into the genetic mechanisms of UFG formation in lantana, we investigated the transcriptomes of young ovaries of two lantana genotypes, GDGHOP-36 (GGO), producing 100% UFGs, and a cultivar Landmark White Lantana (LWL), not producing UFGs. The de novo transcriptome assembly resulted in a total of 90,641 unique transcript sequences with an N50 of 1692 bp, among which, 29,383 sequences contained full-length coding sequences (CDS). There were 214 transcripts associated with the biological processes of gamete production and 10 gene families orthologous to genes known to control unreduced gamete production in Arabidopsis. We identified 925 transcription factor (TF)-encoding sequences, 91 nucleotide-binding site (NBS)-containing genes, and gene families related to drought/salt tolerance and allelopathy. These genomic resources and candidate genes involved in gamete formation will be valuable for developing new tools to control the invasiveness in L. camara, protect native lantana species, and understand the formation of unreduced gametes in plants.

RevDate: 2019-08-05

Faúndez EI, Carvajal MA, J Villablanca (2019)

Alien Invasion: The Case of the Western Conifer-Seed Bug (Heteroptera: Coreidae) in Chile, Overreaction, and Misidentifications.

Journal of medical entomology pii:5542458 [Epub ahead of print].

Leptoglossus occidentalis (Heidemann) is an invasive species introduced in Europe, Asia, and most recently South America. In the present study, we report the overreaction situation caused by this bug in Chile, as it has been confused with kissing bugs (Reduviidae: Triatominae), Chagas' disease vectors. During 2018 and first months of 2019, we received 74 alleged cases of kissing bugs to confirm identification. From these, a total of 63 were identified as L. occidentalis, representing a 85% of the total denounces. Additionally, the first bite case in a human is described. The situation caused by L. occidentalis in Chile is discussed, and an illustrated table is provided to correctly identify this species and tell it apart from Triatomines. It is concluded that L. occidentalis is well established in Chile, and it is necessary to educate the population on recognition of the bug and to avoid overreaction as the species can inflict painful bites, but not transmit any disease.

RevDate: 2019-08-05

Queffelec J, Wooding AL, Greeff JM, et al (2019)

Mechanisms that influence sex ratio variation in the invasive hymenopteran Sirex noctilio in South Africa.

Ecology and evolution, 9(14):7966-7973 pii:ECE35305.

Sirex noctilio is an economically important invasive pest of commercial pine forestry in the Southern Hemisphere. Newly established invasive populations of this woodwasp are characterized by highly male-biased sex ratios that subsequently revert to those seen in the native range. This trend was not observed in the population of S. noctilio from the summer rainfall regions in South Africa, which remained highly male-biased for almost a decade. The aim of this study was to determine the cause of this persistent male bias. As an explanation for this pattern, we test hypotheses related to mating success, female investment in male versus female offspring, and genetic diversity affecting diploid male production due to complementary sex determination. We found that 61% of females in a newly established S. noctilio population were mated. Microsatellite data analysis showed that populations of S. noctilio from the summer rainfall regions in South Africa are far less genetically diverse than those from the winter rainfall region, with mean Nei's unbiased gene diversity indexes of 0.056 and 0.273, respectively. These data also identified diploid males at low frequencies in both the winter (5%) and summer (2%) rainfall regions. The results suggest the presence of a complementary sex determination mechanism in S. noctilio, but imply that reduced genetic diversity is not the main driver of the male bias observed in the summer rainfall region. Among all the factors considered, selective investment in sons appears to have the most significant influence on male bias in S. noctilio populations. Why this investment remains different in frontier or early invasive populations is not clear but could be influenced by females laying unfertilized eggs to avoid diploid male production in populations with a high genetic relatedness.

RevDate: 2019-08-05

van Boheemen LA, Bou-Assi S, Uesugi A, et al (2019)

Rapid growth and defence evolution following multiple introductions.

Ecology and evolution, 9(14):7942-7956 pii:ECE35275.

Rapid adaptation can aid invasive populations in their competitive success. Resource allocation trade-off hypotheses predict higher resource availability or the lack of natural enemies in introduced ranges allow for increased growth and reproduction, thus contributing to invasive success. Evidence for such hypotheses is however equivocal and tests among multiple ranges over productivity gradients are required to provide a better understanding of the general applicability of these theories.Using common gardens, we investigated the adaptive divergence of various constitutive and inducible defence-related traits between the native North American and introduced European and Australian ranges, while controlling for divergence due to latitudinal trait clines, individual resource budgets, and population differentiation, using >11,000 SNPs.Rapid, repeated clinal adaptation in defence-related traits was apparent despite distinct demographic histories. We also identified divergence among ranges in some defence-related traits, although differences in energy budgets among ranges may explain some, but not all, defence-related trait divergence. We do not identify a general reduction in defence in concert with an increase in growth among the multiple introduced ranges as predicted trade-off hypotheses. Synthesis: The rapid spread of invasive species is affected by a multitude of factors, likely including adaptation to climate and escape from natural enemies. Unravelling the mechanisms underlying invasives' success enhances understanding of eco-evolutionary theory and is essential to inform management strategies in the face of ongoing climate change.

OPEN RESEARCH BADGES: This article has been awarded Open Materials, Open Data, Preregistered Research Designs Badges. All materials and data are publicly accessible via the Open Science Framework at https://doi.org/10.6084/m9.figshare.8028875.v1, https://github.com/lotteanna/defence_adaptation,https://doi.org/10.1101/435271.

RevDate: 2019-08-05

Winkler DE, Chapin KJ, François O, et al (2019)

Multiple introductions and population structure during the rapid expansion of the invasive Sahara mustard (Brassica tournefortii).

Ecology and evolution, 9(14):7928-7941 pii:ECE35239.

The specific mechanisms that result in the success of any species invasion case are difficult to document. Reproductive strategies are often cited as a primary driver of invasive success, with human activities further facilitating invasions by, for example, acting as seed vectors for dispersal via road, train, air, and marine traffic, and by producing efficient corridors for movement including canals, drainages, and roadways. Sahara mustard (Brassica tournefortii) is a facultative autogamous annual native to Eurasia that has rapidly invaded the southwestern United States within the past century, displacing natives, and altering water-limited landscapes in the southwest. We used a genotyping-by-sequencing approach to study the population structure and spatial geography of Sahara mustard from 744 individuals from 52 sites across the range of the species' invasion. We also used herbaria records to model range expansion since its initial introduction in the 1920s. We found that Sahara mustard occurs as three populations in the United States unstructured by geography, identified three introduction sites, and combined herbaria records with genomic analyses to map the spread of the species. Low genetic diversity and linkage disequilibrium are consistent with self-fertilization, which likely promoted rapid invasive spread. Overall, we found that Sahara mustard experienced atypical expansion patterns, with a relatively constant rate of expansion and without the lag phase that is typical of many invasive species.

RevDate: 2019-08-05

Ladino G, Ospina-Bautista F, Estévez Varón J, et al (2019)

Ecosystem services provided by bromeliad plants: A systematic review.

Ecology and evolution, 9(12):7360-7372 pii:ECE35296.

The unprecedented loss of biological diversity has negative impacts on ecosystems and the associated benefits which they provide to humans. Bromeliads have high diversity throughout the Neotropics, but they have been negatively affected by habitat loss and fragmentation, climate change, invasive species, and commercialization for ornamental purpose. These plants provide direct benefits to the human society, and they also form microecosystems in which accumulated water and nutrients support the communities of aquatic and terrestrial species, thus maintaining local diversity. We performed a systematic review of the contribution of bromeliads to ecosystem services across their native geographical distribution. We showed that bromeliads provide a range of ecosystem services such as maintenance of biodiversity, community structure, nutrient cycling, and the provisioning of food and water. Moreover, bromeliads can regulate the spread of diseases, and water and carbon cycling, and they have the potential to become important sources of chemical and pharmaceutical products. The majority of this research was performed in Brazil, but future research from other Neotropical countries with a high diversity of bromeliads would fill the current knowledge gaps and increase the generality of these findings. This systematic review identified that future research should focus on provisioning, regulating, and cultural services that have been currently overlooked. This would enhance our understanding of how bromeliad diversity contributes to human welfare, and the negative consequences that loss of bromeliad plants can have on communities of other species and the healthy functioning of the entire ecosystems.

RevDate: 2019-08-05

Walls SC, Barichivich WJ, Chandler J, et al (2019)

Seeking shelter from the storm: Conservation and management of imperiled species in a changing climate.

Ecology and evolution, 9(12):7122-7133 pii:ECE35277.

Climate change is anticipated to exacerbate the extinction risk of species whose persistence is already compromised by habitat loss, invasive species, disease, or other stressors. In coastal areas of the southeastern United States (USA), many imperiled vertebrates are vulnerable to hurricanes, which climate models predict to become more severe in the 21st century. Despite this escalating threat, explicit adaptation strategies that address hurricane threats, in particular, and climate change more generally, are largely underrepresented in recovery planning and implementation. We provide a basis for stronger emphasis on strategic planning for imperiled species facing the increasing threat of catastrophic hurricanes. Our reasoning comes from observations of short-term environmental and biological impacts of Hurricane Michael, which impacted the Gulf Coast of the southeastern USA in October 2018. During this storm, St. Marks National Wildlife Refuge, located along the northern Gulf of Mexico's coast in the panhandle region of Florida, received storm surge that was 3.0-3.6 m (NAVD88) above sea level. Storm surge pushed sea water into some ephemeral freshwater ponds used for breeding by the federally threatened frosted flatwoods salamander (Ambystoma cingulatum). After the storm, specific conductance across all ponds measured varied from 80 to 23,100 µS/cm, compared to 75 to 445 µS/cm in spring 2018. For 17 overwashed wetlands that were measured in both spring and fall 2018, posthurricane conductance observations were, on average, more than 90 times higher than in the previous spring, setting the stage for varying population responses across this coastal landscape. Importantly, we found live individual flatwoods salamanders at both overwashed and non-overwashed sites, although we cannot yet assess the demographic consequences of this storm. We outline actions that could be incorporated into climate adaptation strategies and recovery planning for imperiled species, like A. cingulatum, that are associated with freshwater coastal wetlands in hurricane-prone regions.

RevDate: 2019-08-05

Crenna E, Sinkko T, S Sala (2019)

Biodiversity impacts due to food consumption in Europe.

Journal of cleaner production, 227:378-391.

Food security and biodiversity conservation are closely interconnected challenges to be addressed to achieve a sustainable food system on a global scale. Due to the complex nature of food production and consumption system, quantifying the impacts of food supply chains on biodiversity is challenging. Life cycle assessment (LCA) allows for systematically addressing environmental impacts along supply chains, representing a reference methodology that can be applied for assessing food systems. In the present study, 32 representative food products of consumption in the European Union (EU) were selected and their environmental impacts calculated through a process-based LCA. The potential contribution of EU food consumption to the current biodiversity decline has been evaluated adopting both midpoint and endpoint indicators. A comparison of the impact drivers was performed. Meat products, the underpinning land use for agricultural purposes, and climate change represent the main hotspots of impacts on biodiversity. Notwithstanding several drivers of biodiversity loss can be accounted for with LCA, the evidence of the increasing biodiversity decline on both a European and a global scale indicates that the assessment system should be further expanded, especially for what concerns refining impact categories such as ecotoxicity, and including resource overexploitation, and impact due to invasive species. This study illustrates: how far the current LCA based impact assessment framework may help to address the drivers of biodiversity loss; which are the main uncertainties associated to results stemming from the application of different endpoint methods; which aspects need to be elaborated further to ensure a comprehensive assessment of biodiversity impacts due to food production and consumption.

RevDate: 2019-08-06
CmpDate: 2019-08-06

Jiang C, Shui W, Jian XM, et al (2019)

[Soil microbial community characteristics in degraded karst tiankeng invaded by Eupatorium adenophorum.].

Ying yong sheng tai xue bao = The journal of applied ecology, 30(6):2002-2010.

After invading the grand negative landform karst degraded tiankeng, Eupatorium adenophorum will affect the plant diversity, community succession and natural ecological restoration of degraded tiankeng by changing soil microbial community. Taking the degraded tiankeng "Bajiaxiantang" as the research area, the soil around E. adenophorum roots in different habitats was selected to explore the microbial community characteristics of E. adenophorum roots using the Biolog-ECO micro-plate method. The results showed that the invasion degree of E. adenophorum was in order of pit slope shrub-grassland > pit bottom grassland > pit slope forest > pit head shrub-grassland. The characteristics of E. adenophorum varied among different habitats due to habitat heterogeneity. The change of microbial community metabolic activity, dominance index, richness index and evenness index of E. adenophorum roots was closely related with the invasion degree, with significant diffe-rence between inside and outside of the tiankeng. Amino acids and polymers were the main carbon sources utilized by soil microorganism. The α diversity of herbaceous plants in different habitats were correlated with that of soil microbial community. The diversity of soil microbial community around E. adenophorum roots increased significantly with the increases of invasion level, which could form a microenvironment conducive to invasion and colonization. In the future, the degraded tiankeng would eventually form the climax community of underground forests with community succession and natural ecological restoration, which might result in the disappearance of E. adenophorum in the degraded tiankeng.

RevDate: 2019-08-06
CmpDate: 2019-08-06

Sarabeev V, Balbuena JA, S Morand (2018)

Invasive parasites are detectable by their abundance-occupancy relationships: the case of helminths from Liza haematocheilus (Teleostei: Mugilidae).

International journal for parasitology, 48(9-10):793-803.

The biogeographic patterns of abundance and prevalence of helminths from Liza haematocheilus were studied across its native (Sea of Japan) and introduced (Sea of Azov) distribution ranges. Abundance-occupancy relationships (AORs) were tested for the core-satellite and enemy release (ERH) species hypotheses in eight and 14 host samples from the native and introduced host ranges, respectively. The AOR model fitted parasite data extremely well, irrespective of whether the host or the parasite species were native or invasive. Except for co-introduced monogeneans, species were less abundant and prevalent in the introduced host population than in the native one, which agrees well with the ERH. Two occupancy patterns were observed. A unimodal, right-skewed distribution of prevalence frequency was common for the acquired groups of helminth parasites in the introduced range, whereas a bimodal distribution was more common in the native range. Core species in the native range were monogeneans, adult and larval digeneans, whereas host-specific, co-introduced monogeneans were the only core species in the introduced range. Acquired grey-mullet specialists and host generalists infected only a small portion of the introduced host population with low mean abundance. These results indicate that strict host specificity, together with a direct life cycle, are the traits that enabled helminth species to entirely occupy the invasive host population. The AORs showed that parasite individuals tend to accumulate in a relatively small fraction of susceptible introduced hosts, probably as an adaptation to enhance mating opportunities, thereby providing a mechanistic explanation of the ERH. All this evidence suggests that co-introduced and acquired species use the introduced host population in very different ways. Therefore, we posit that the examination of AORs can be instrumental in understanding the role of co-introduced parasites in invasion theory.

RevDate: 2019-08-06
CmpDate: 2019-08-06

Eritja R, Palmer JRB, Roiz D, et al (2017)

Direct Evidence of Adult Aedes albopictus Dispersal by Car.

Scientific reports, 7(1):14399.

Whereas the Asian tiger mosquito (Aedes albopictus) has low active dispersal capabilities, its worldwide colonization has been rapid. Indirect evidence and informal reports have long implicated passive transportation in cars, but this has not previously been studied systematically given the difficulties of real-time roadside surveys. Here we report the first sampling study confirming that adult tiger mosquitoes travel with humans in cars and enabling us to estimate the frequency of these events. We combine the results with citizen science data to model the car-facilitated dispersal of Aedes albopictus at a nationwide level. During the summer of 2015, we sampled 770 cars in north-eastern Spain, discovering 4 adult female tiger mosquitoes that had entered cars prior to sampling. Our Bayesian model suggests that of the 6.5 million daily car trips in the Barcelona metropolitan area, between 13,000 and 71,500 facilitate tiger mosquito movement, and that Barcelona is the largest source of inter-province tiger mosquito transfers in Spain. Our results are supported by expert-validated citizen science data, and will contribute to better understanding the tiger mosquito's invasion process and ultimately lead to more effective vector control strategies.

RevDate: 2019-08-05
CmpDate: 2019-08-05

Cope RC, Ross JV, Wittmann TA, et al (2019)

Predicting the Risk of Biological Invasions Using Environmental Similarity and Transport Network Connectedness.

Risk analysis : an official publication of the Society for Risk Analysis, 39(1):35-53.

Understanding the risk of biological invasions associated with particular transport pathways and source regions is critical for implementing effective biosecurity management. This may require both a model for physical connectedness between regions, and a measure of environmental similarity, so as to quantify the potential for a species to be transported from a given region and to survive at a destination region. We present an analysis of integrated biosecurity risk into Australia, based on flights and shipping data from each global geopolitical region, and an adaptation of the "range bagging" method to determine environmental matching between regions. Here, we describe global patterns of environmental matching and highlight those regions with many physical connections. We classify patterns of global invasion risk (high to low) into Australian states and territories. We validate our analysis by comparison with global presence data for 844 phytophagous insect pest species, and produce a list of high-risk species not previously known to be present in Australia. We determined that, of the insect pest species used for validation, the species most likely to be present in Australia were those also present in geopolitical regions with high transport connectivity to Australia, and those regions that were geographically close, and had similar environments.

RevDate: 2019-08-06
CmpDate: 2019-08-06

Wu Y, Wang H, EA Hadly (2017)

Invasion of Ancestral Mammals into Dim-light Environments Inferred from Adaptive Evolution of the Phototransduction Genes.

Scientific reports, 7:46542.

Nocturnality is a key evolutionary innovation of mammals that enables mammals to occupy relatively empty nocturnal niches. Invasion of ancestral mammals into nocturnality has long been inferred from the phylogenetic relationships of crown Mammalia, which is primarily nocturnal, and crown Reptilia, which is primarily diurnal, although molecular evidence for this is lacking. Here we used phylogenetic analyses of the vision genes involved in the phototransduction pathway to predict the diel activity patterns of ancestral mammals and reptiles. Our results demonstrated that the common ancestor of the extant Mammalia was dominated by positive selection for dim-light vision, supporting the predominate nocturnality of the ancestral mammals. Further analyses showed that the nocturnality of the ancestral mammals was probably derived from the predominate diurnality of the ancestral amniotes, which featured strong positive selection for bright-light vision. Like the ancestral amniotes, the common ancestor of the extant reptiles and various taxa in Squamata, one of the main competitors of the temporal niches of the ancestral mammals, were found to be predominate diurnality as well. Despite this relatively apparent temporal niche partitioning between ancestral mammals and the relevant reptiles, our results suggested partial overlap of their temporal niches during crepuscular periods.

RevDate: 2019-08-03

Liu HB, Rui L, Feng YQ, et al (2019)

Molecular Characterization and Functional Analysis of Three Autophagy Genes, BxATG5, BxATG9, and BxATG16, in Bursaphelenchus xylophilus.

International journal of molecular sciences, 20(15): pii:ijms20153769.

The pine wood nematode (PWN), Bursaphelenchus xylophilus, is the pathogen responsible for pine wilt disease (PWD), a devastating forest disease with a pathogenic mechanism that remains unclear. Autophagy plays a crucial role in physiological and pathological processes in eukaryotes, but its regulatory mechanism and significance in PWN are unknown. Therefore, we cloned and characterized three autophagy genes, BxATG5, BxATG9, and BxATG16, in PWN. BxATG9 and BxATG16 were efficiently silenced through RNA interference, and we found that BxATG16 positively regulated the expression of BxATG5. Silencing BxATG9 and BxATG16 severely inhibited feeding and reproduction in PWN, indicating that autophagy is essential for these processes. We then examined the expression patterns of these three autophagy genes in PWN under the stresses of α-pinene and H2O2, the main defense substances of pine trees, and during the development of PWD using quantitative reverse transcription polymerase chain reaction. The expression levels of BxATG5, BxATG9, and BxATG16 all significantly increased after nematodes were stressed with α-pinene and H2O2 and inoculated into pine trees, suggesting that autophagy plays an important role in the defense and pathogenesis of PWN. In this study, the molecular characteristics and functions of the autophagy genes BxATG5, BxATG9, and BxATG16 in PWN were elucidated.

RevDate: 2019-08-02

Padilla P, Courant J, A Herrel (2019)

Allocation trade-offs impact organ size and muscle architecture in an invasive population of Xenopus laevis in Western France.

Journal of anatomy [Epub ahead of print].

Invasive species are a global scourge and often negatively impact native species. Understanding the expansion and dispersal limits of these species is essential. As previous studies have demonstrated increased locomotor performance for populations at the edge of the range of expanding populations, studies of locomotion including the anatomical and physiological traits underlying dispersal capacity are of interest. We focus here on an invasive population of Xenopus laevis introduced in France nearly forty years ago. Previous studies have demonstrated differences in mobility between populations from the centre and the edge of the invasive range, with individuals from the range edge possessing a higher endurance capacity. We test here whether range-edge frogs show anatomical differences in organs or muscles underlying these observed differences of performance. We dissected 10 males and 10 females from central and range-edge sites (40 animals in total) and measured the mass of their organs and the mass, the length, and the physiological cross-sectional area (PCSA) of 28 hind limb muscles. Our results show anatomical differences with individuals from the range edge possessing heavier, longer and more forceful muscles. Moreover, females from the range edge had a heavier heart but lighter stomach than those of the centre of the range. Future studies comparing the morphology between native and invasive populations in other regions or for other species will be especially insightful to better understand the possible adaptive changes in invasive populations and the limits on dispersal capacity.

RevDate: 2019-08-02

Wauters LA, Mazzamuto MV, Santicchia F, et al (2019)

Interspecific competition affects the expression of personality-traits in natural populations.

Scientific reports, 9(1):11189 pii:10.1038/s41598-019-47694-4.

Competition between animal species can cause niche partitioning and shape an individual's phenotype, including its behaviour. However, little is known about effects of interspecific competition on personality, the among-individual variation in behaviour that is consistent across different spatial and temporal contexts. We investigated whether alien grey squirrels (Sciurus carolinensis) influenced the expression of personality traits in native red squirrels (Sciurus vulgaris). In Italy, alien grey squirrels replaced native reds through competition for food resources and space, reducing breeding and recruitment in the native species. We compared personality of red squirrels in red-only (no interspecific competition) and red-grey (with interspecific competition) sites, using arena-tests. The trait activity was measured by Open Field Test while sociability and avoidance were quantified by Mirror Image Stimulation test. Red squirrels co-occurring with the alien species had higher sociability scores and higher between-individual variation in sociability than in red-only sites. Differences in activity and avoidance were not significant. Personality - fitness relationships were not affected by presence or absence of grey squirrels, suggesting that the expression of sociability in red squirrels was not due to short-term selection, but was likely the result of context-related advantages when co-occurring with the competing species.

RevDate: 2019-08-02
CmpDate: 2019-08-02

da Silva ÍF, EA Vieira (2019)

Phytotoxic potential of Senna occidentalis (L.) Link extracts on seed germination and oxidative stress of Ipê seedlings.

Plant biology (Stuttgart, Germany), 21(4):770-779.

Senna occidentalis is an invasive plant producing a series of allelochemicals that might inhibit the development of other plants. The objective of this study was to assess the phytotoxic effect of S. occidentalis extracts on the germination, development and antioxidant defence of the native species Tabebuia chrysotricha, T. pentaphylla, T. roseoalba and Handroanthus impetiginosus (Ipê species). We evaluated the effects of chemicals extracted from S. occidentalis on the germination rate, germination speed index (GSI) and biometric parameters of the test species under controlled conditions. The effect of the extracts on the pigment content, amount of H2 O2 and malondialdehyde (MDA), and the activity of the antioxidant enzymes in roots and leaves were also tested. Alkaloids, coumarins, phenols, saponins, free steroids and condensed tannins were present in all extracts of S. occidentalis, while catechins were present only in leaf and stem extracts. Stem and root extracts caused a growth reduction in all Ipê species and total inhibition of seed germination in T. chrysotricha and T. roseoalba. All target species showed an increase in H2 O2 and MDA in radicles and leaves. Oxidative stress contributed strongly to the morphological changes, such as seed blackening, thinning and darkening of radicle tips and reduction of biomass allocation in all Ipê species. Although there was activation of antioxidant defence mechanisms, such as an increase in activity of ascorbate peroxidase (APX) and peroxidase (POD) enzymes, the joint action of the allelochemicals caused phytotoxicity, leading to cell dysfunction in all Ipê species.

RevDate: 2019-08-02
CmpDate: 2019-08-02

Abram PK, CE Moffat (2018)

Rethinking biological control programs as planned invasions.

Current opinion in insect science, 27:9-15.

Biological control of pests with their natural enemies essentially consists of planned invasions, with the opportunity to select both the invader and the invaded environment. Recent advances in invasion science link 'intrinsic invasion factors' (life history and behavioral traits) with invader success; connect 'extrinsic invasion factors' (abiotic and biotic aspects of the invaded environment) with environmental invasibility; and demonstrate that their interaction leads not only to ecologically driven variability but also to rapid evolutionary change in biocontrol systems. However, current theory and empirical evidence from invasion science have not yet been extensively adopted into biological control research and practice.

RevDate: 2019-08-01

Lim SR, Lee DH, Park SY, et al (2019)

Wild Nutria (Myocastor coypus) Is a Potential Reservoir of Carbapenem-Resistant and Zoonotic Aeromonas spp. in Korea.

Microorganisms, 7(8): pii:microorganisms7080224.

The emergence and spread of antibiotic-resistant Aeromonas spp. is a serious public and animal health concern. Wild animals serve as reservoirs, vectors, and sentinels of these bacteria and can facilitate their transmission to humans and livestock. The nutria (Myocastor coypus), a semi-aquatic rodent, currently is globally considered an invasive alien species that has harmful impacts on natural ecosystems and carries various zoonotic aquatic pathogens. This study aimed to determine the prevalence of antibiotic-resistant zoonotic Aeromonas spp. in wild invasive nutrias captured in Korea during governmental eradication program. Three potential zoonotic Aeromonas spp. (A. hydrophila, A. caviae, and A. dhakensis) were identified among isolates from nutria. Some strains showed unexpected resistance to fluoroquinolones, third-generation cephalosporins, and carbapenems. In carbapenem-resistant isolates, the cphA gene, which is related to intrinsic resistance of Aeromonas to carbapenems, was identified, and phylogenetic analysis based on this gene revealed the presence of two major groups represented by A. hydrophila (including A. dhakensis) and other Aeromonas spp. These results indicate that wild nutrias in Korea are a potential reservoir of zoonotic and antibiotic-resistant Aeromonas spp. that can cause infection and treatment failure in humans. Thus, measures to prevent contact of wild nutrias with livestock and humans are needed.

RevDate: 2019-08-01

Evans JS, Erwin PM, Shenkar N, et al (2018)

A comparison of prokaryotic symbiont communities in nonnative and native ascidians from reef and harbor habitats.

FEMS microbiology ecology, 94(9):.

Harbor systems represent passive gateways for the introduction of nonnative ascidians that compete with the surrounding benthos and may spread through localized dispersal, even populating adjacent natural reefs. To investigate the potential role of microbial symbionts in the success of ascidian introductions and spread, we evaluated the host-specificity of prokaryotic communities within two ascidian species commonly found off the North Carolina coast. Replicate samples of the native ascidian Eudistoma capsulatum, the nonnative ascidian Distaplia bermudensis and seawater were collected from artificial (harbor) and natural reef substrates. Prokaryotic communities in seawater samples and ascidian tunics were characterized via next-generation sequencing of partial 16S rRNA gene sequences. Ascidian microbiomes clustered strongly in response to host species, with significant differences in community structure between the two species and seawater. Further, symbiont community structure differed significantly between E. capsulatumindividuals collected from artificial and natural habitats, though this was not the case for D. bermudensis. These findings suggested that some ascidian species possess stable microbial symbiont communities that allow them to thrive in a wide range of habitats, while other species rely on the restructuring of their microbial communities with specific symbionts (e.g. Chelativorans) to survive under particular environmental conditions such as increased pollution.

RevDate: 2019-07-31

McDonald IJ, M McKinnon (2019)

Communicating biosecurity information to Australian-registered veterinarians.

Australian veterinary journal [Epub ahead of print].

OBJECTIVE: Updating veterinarians (vets) on the latest biosecurity resources, information and alerts is important to ensure protection of domesticated and native animals. This preliminary questionnaire aimed to better understand the communication preferences of Australian-registered vets for biosecurity information, and their trust of these sources.

METHODS: An online questionnaire asking vets about their current communication preferences for biosecurity information, and their level of trust of these was created and distributed to Australian-registered vets.

RESULTS: Survey respondents (158) use and highly trust communication from (in order) vet and animal health organisations, vet surgeons' boards, the scientific literature, and government agencies.

CONCLUSIONS: This preliminary study identifies that using vet surgeon's boards, government agencies and vet and animal health organisations may be an effective means for communicating biosecurity information to vets. Future research should consider which sources vets trust and why, to facilitate effective communication to them and the clients they serve.

RevDate: 2019-07-31

Piper AM, Batovska J, Cogan NOI, et al (2019)

Prospects and challenges of implementing DNA metabarcoding for high-throughput insect surveillance.

GigaScience, 8(8):.

Trap-based surveillance strategies are widely used for monitoring of invasive insect species, aiming to detect newly arrived exotic taxa as well as track the population levels of established or endemic pests. Where these surveillance traps have low specificity and capture non-target endemic species in excess of the target pests, the need for extensive specimen sorting and identification creates a major diagnostic bottleneck. While the recent development of standardized molecular diagnostics has partly alleviated this requirement, the single specimen per reaction nature of these methods does not readily scale to the sheer number of insects trapped in surveillance programmes. Consequently, target lists are often restricted to a few high-priority pests, allowing unanticipated species to avoid detection and potentially establish populations. DNA metabarcoding has recently emerged as a method for conducting simultaneous, multi-species identification of complex mixed communities and may lend itself ideally to rapid diagnostics of bulk insect trap samples. Moreover, the high-throughput nature of recent sequencing platforms could enable the multiplexing of hundreds of diverse trap samples on a single flow cell, thereby providing the means to dramatically scale up insect surveillance in terms of both the quantity of traps that can be processed concurrently and number of pest species that can be targeted. In this review of the metabarcoding literature, we explore how DNA metabarcoding could be tailored to the detection of invasive insects in a surveillance context and highlight the unique technical and regulatory challenges that must be considered when implementing high-throughput sequencing technologies into sensitive diagnostic applications.

RevDate: 2019-07-31

Nogueira CB, Menéndez E, Ramírez-Bahena MH, et al (2019)

The N-fixing legume Periandra mediterranea constrains the invasion of an exotic grass (Melinis minutiflora P. Beauv) by altering soil N cycling.

Scientific reports, 9(1):11033 pii:10.1038/s41598-019-47380-5.

Melinis minutiflora is an invasive species that threatens the biodiversity of the endemic vegetation of the campo rupestre biome in Brazil, displacing the native vegetation and favouring fire spread. As M. minutiflora invasion has been associated with a high nitrogen (N) demand, we assessed changes in N cycle under four treatments: two treatments with contrasting invasion levels (above and below 50%) and two un-invaded control treatments with native vegetation, in the presence or absence of the leguminous species Periandra mediterranea. This latter species was considered to be the main N source in this site due to its ability to fix N2 in association with Bradyrhizobia species. Soil proteolytic activity was high in treatments with P. mediterranea and in those severely invaded, but not in the first steps of invasion. While ammonium was the N-chemical species dominant in plots with native species, including P.mediterranea, soil nitrate prevailed only in fully invaded plots due to the stimulation of the nitrifying bacterial (AOB) and archaeal (AOA) populations carrying the amoA gene. However, in the presence of P. mediterranea, either in the beginning of the invasion or in uninvaded plots, we observed an inhibition of the nitrifying microbial populations and nitrate formation, suggesting that this is a biotic resistance strategy elicited by P. mediterranea to compete with M. minutiflora. Therefore, the inhibition of proteolytic activity and the nitrification process were the strategies elicited by P.mediterranea to constrain M.munitiflora invasion.

RevDate: 2019-07-30

Briscoe NJ, Elith J, Salguero-Gómez R, et al (2019)

Forecasting species range dynamics with process-explicit models: matching methods to applications.

Ecology letters [Epub ahead of print].

Knowing where species occur is fundamental to many ecological and environmental applications. Species distribution models (SDMs) are typically based on correlations between species occurrence data and environmental predictors, with ecological processes captured only implicitly. However, there is a growing interest in approaches that explicitly model processes such as physiology, dispersal, demography and biotic interactions. These models are believed to offer more robust predictions, particularly when extrapolating to novel conditions. Many process-explicit approaches are now available, but it is not clear how we can best draw on this expanded modelling toolbox to address ecological problems and inform management decisions. Here, we review a range of process-explicit models to determine their strengths and limitations, as well as their current use. Focusing on four common applications of SDMs - regulatory planning, extinction risk, climate refugia and invasive species - we then explore which models best meet management needs. We identify barriers to more widespread and effective use of process-explicit models and outline how these might be overcome. As well as technical and data challenges, there is a pressing need for more thorough evaluation of model predictions to guide investment in method development and ensure the promise of these new approaches is fully realised.

RevDate: 2019-07-30

Craven D, Knight TM, Barton KE, et al (2019)

Dissecting macroecological and macroevolutionary patterns of forest biodiversity across the Hawaiian archipelago.

Proceedings of the National Academy of Sciences of the United States of America pii:1901954116 [Epub ahead of print].

Biodiversity patterns emerge as a consequence of evolutionary and ecological processes. Their relative importance is frequently tested on model ecosystems such as oceanic islands that vary in both. However, the coarse-scale data typically used in biogeographic studies have limited inferential power to separate the effects of historical biogeographic factors (e.g., island age) from the effects of ecological ones (e.g., island area and habitat heterogeneity). Here, we describe local-scale biodiversity patterns of woody plants using a database of more than 500 forest plots from across the Hawaiian archipelago, where these volcanic islands differ in age by several million years. We show that, after controlling for factors such as island area and heterogeneity, the oldest islands (Kaua'i and O'ahu) have greater native species diversity per unit area than younger islands (Maui and Hawai'i), indicating an important role for macroevolutionary processes in driving not just whole-island differences in species diversity, but also local community assembly. Further, we find that older islands have a greater number of rare species that are more spatially clumped (i.e., higher within-island β-diversity) than younger islands. When we included alien species in our analyses, we found that the signal of macroevolutionary processes via island age was diluted. Our approach allows a more explicit test of the question of how macroevolutionary factors shape not just regional-scale biodiversity, but also local-scale community assembly patterns and processes in a model archipelago ecosystem, and it can be applied to disentangle biodiversity drivers in other systems.

RevDate: 2019-07-30

García-Valcárcel AI, Martínez-Ferrer MT, Campos-Rivela JM, et al (2019)

Analysis of pesticide residues in honeybee (Apis mellifera L.) and in corbicular pollen. Exposure in citrus orchard with an integrated pest management system.

Talanta, 204:153-162.

In the last years, the honeybee population is facing growing threats such as expansion of pathogens, incorrect use of phytosanitary products and environmental contaminants, loss or fragmentation of habitat, invasive species and climate change. The citrus cropping by Integrated Pest Management (IPM) in Spain combines strategies to reduce pest populations preventing environmental problems and reducing levels of damage by using chemicals only when it is strictly necessary. The goal of this study is to develop a simple analytical method to evaluate pesticide residue levels in honeybees and corbicular pollen when honeybees are exposed to plant protection products (PPPs) used in integrated pest management citrus orchards. The proposed method is based in an ultrasound assisted extraction procedure followed by a dispersive solid phase extraction (d-SPE) clean-up with alumina and LC-MS/MS pesticides determination. The method was validated in samples of honeybee and corbicular pollen for 10 pesticides commonly used in citrus orchards under IPM. This procedure was compared with QuEChERS methodologies for these matrices. The developed method was applied to determine pesticides in both matrices in a two -year study in citrus orchards.

RevDate: 2019-07-30
CmpDate: 2019-07-30

Stefanowicz AM, Zubek S, Stanek M, et al (2019)

Invasion of Rosa rugosa induced changes in soil nutrients and microbial communities of coastal sand dunes.

The Science of the total environment, 677:340-349.

The aim of this study was to investigate the influence of R. rugosa invasion on soil physicochemical and microbial properties of coastal sand dunes. The study was performed at 25 paired invaded-native plots along the Hel Peninsula at the coast of the Baltic Sea. A number of soil physicochemical and microbial parameters were measured, namely organic matter layer thickness, pH, electrical conductivity, organic C, total Ca, N, Na, P, N-NH4, N-NO3 and P-PO4 concentrations, phospholipid and neutral fatty acid (PLFA, NLFA) markers of total microbial, bacterial, fungal biomass and microbial community structure, as well as arbuscular mycorrhizal fungi (AMF) spore and species numbers, and the degree of AMF root colonization. Since potential alterations in soil parameters induced by R. rugosa may be related to large amounts of secondary metabolites provided to the soil with litter or root exudates, total phenolic concentration in senescing tissues of R. rugosa and native species was compared. Rosa rugosa invasion was associated with increased organic C, total N and P-PO4 concentrations in mineral soil relative to native vegetation. Organic matter layer under R. rugosa was thicker, had higher pH and Ca concentration. Rosa rugosa invasion was associated with reduced total microbial, bacterial and G+ bacterial biomass and increased AMF biomass markers (16:1ω5 NLFA and 16:1ω5 NLFA/PLFA), and changes in microbial community structure in mineral soil. The reduction in total and bacterial biomass under R. rugosa might have been related to the production of secondary metabolites as total phenolic concentration was approx. 5 times higher in senescing tissues of R. rugosa than in native vegetation. The observed increase in element concentrations and alterations in microbial community structure suggest that invasion of R. rugosa may threaten nutrient-poor habitats of coastal dunes. Changes in the soil environment may hinder restoration of these valuable habitats after invader removal.

RevDate: 2019-07-30
CmpDate: 2019-07-30

Zhao M, Lu X, Zhao H, et al (2019)

Ageratina adenophora invasions are associated with microbially mediated differences in biogeochemical cycles.

The Science of the total environment, 677:47-56.

Invasive plant species may alter soil nutrient availability to facilitate their growth and competitiveness. However, the roles and functional mechanisms of plant-associated microbes that mediate these soil biogeochemical cycles remain elusive. Here, we studied how soil microorganisms and their functional processes differed between soils invaded by Ageratina adenophora and adjacent non-invaded soils in a region of China with heavy invasion. Our results indicated that soil nitrogen contents were over 4.32 mg/kg higher (p < 0.05) in both rhizosphere soils and bulk soils dominated by A. adenophora as compared with those in soils dominated by non-invaded plants. Concurrently, soil microbial-mediated functional processes, i.e. nitrogen fixation rate, nitrification rate and ammonification rate, were also significantly (p < 0.05) higher in either rhizosphere soils or bulk soils of invasive A. adenophora. Using a functional gene microarray, we found higher relative abundances of soil microbial genes involved in N cycling processes in A. adenophora soils, e.g. nifH, required for nitrogen fixation, which significantly correlated with ammonia contents (r = 0.35 in bulk soils, r = 0.37 in rhizosphere soils, p < 0.05) and the nitrogen fixation rate (r = 0.44, p < 0.05). We also found that the relative abundances of labile carbon decomposition genes were higher in invasive A. adenophora soils, implying a potential higher availability of carbon. These results suggest that the soil surrounding the invasive plant A. adenophora is a self-reinforcing environment. The plant litter and rhizosphere environment of the invasive may influence soil microbial communities, promoting self-supporting soil processes. Alternatively, the regions invaded by A. adenophora may have already had properties that facilitated these beneficial microbial community traits, allowing easier invasion by the exotics. Both scenarios offer important insights for the mitigation of plant invasion and provide an ecosystem-level understanding of the invasive mechanisms utilized by alien plants.

RevDate: 2019-07-30
CmpDate: 2019-07-30

Mathai PP, Dunn HM, Magnone P, et al (2018)

Spatial and temporal characterization of epiphytic microbial communities associated with Eurasian watermilfoil: a highly invasive macrophyte in North America.

FEMS microbiology ecology, 94(12):.

Bacterial communities that inhabit the surface of aquatic plants are thought to play a critical role in relation to host fitness and function. However, little is known about their structure and dynamics in comparison with those of bacterioplankton. In this study, we performed a comprehensive spatial and temporal characterization of epibacterial communities associated with Eurasian watermilfoil (EWM; Myriophyllum spicatum), an invasive macrophyte, which has established itself in thousands of lakes across North America. EWM samples were collected from 10 lakes in Minnesota, once a month, for six consecutive months, along with surrounding water and sediment. High-throughput DNA sequencing analyses, performed on all samples (n = 522) using the Illumina platform, indicated that EWM-associated epibacterial communities were distinct from those found in water and sediment. EWM-specific microbiota was comprised of operational taxonomic units classified to the families Rhodobacteraceae, Comamonadaceae, Cyanobacteria Subsection I Family I, Aeromonadaceae, Planctomycetaceae, Sphingomonadaceae and Verrucomicrobiaceae. In addition, several identified taxa were overrepresented in EWM samples when compared to water and sediment. Amongst all the environmental factors examined, water temperature had the greatest influence on epibacterial community structure. Our findings suggest that EWM harbor specific, but temporally adapted, epibacterial communities that are potentially involved in host-microbe interactions.

RevDate: 2019-07-29

Queiroz-Sousa J, Keith SA, David GS, et al (2019)

Species richness and functional structure of fish assemblages in three freshwater habitats: effects of environmental factors and management.

Journal of fish biology [Epub ahead of print].

In this study, the inverted trophic hypothesis was tested in the freshwater fish communities of a reservoir. The distribution of fish species in three freshwater habitats in the Jurumirim Reservoir, Brazil, was examined using both species richness and the relative proportions of different trophic groups. These groups were used as a proxy for functional structure in an attempt to test the ability of these measures to assess fish diversity. Assemblage structures were first described using non-metric multidimensional scaling (NMDS). The influence of environmental conditions for multiple fish assemblage response variables (richness, total abundance and abundance per trophic group) was tested using generalised linear mixed models (GLMM). The metric typically employed to describe diversity; i.e., species richness, was not related to environmental conditions. However, absolute species abundance was relatively well explained with up to 54% of the variation in the observed data accounted for. Differences in the dominance of trophic groups were most apparent in response to the presence of introduced fish species: the iliophagous and piscivorous trophic groups were positively associated, while detritivores and herbivores were negatively associated, with the alien species. This suggests that monitoring functional diversity might be more valuable than species diversity for assessing effects of disturbances and managements policies on the fish community. This article is protected by copyright. All rights reserved.

RevDate: 2019-07-29

Tamburello N, Ma BO, IM Côté (2019)

From individual movement behaviour to landscape-scale invasion dynamics and management: a case study of lionfish metapopulations.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1781):20180057.

Modelling the dynamics of small, interconnected populations, or metapopulations, can help pinpoint habitat patches that are critical for population persistence in patchy habitats. For conservation purposes, these patches are typically earmarked for protection, but for invasive species management, these patches could be targeted to hasten the populations' demise. Here, we show how metapopulation modelling, coupled with an understanding of size-dependent dispersal behaviour, can be used to help optimize the distribution of limited resources for culling specific populations of invasive Indo-Pacific lionfish (Pterois volitans) in the western Atlantic. Through simulation using fitted model parameters, we derive three insights that can inform management. First, culling lionfish from target patches reduces the probability of lionfish occupancy at surrounding patches. Second, this effect depends on patch size and connectivity, but is strongest at the local scale and decays with distance. Finally, size-dependent dispersal in lionfish means that size-selective culling can change both a population's size distribution and dispersal potential, with cascading effects on network connectivity, population dynamics and management outcomes. By explicitly considering seascape structure and movement behaviour when allocating effort to the management of invasive species, managers can optimize resource use to improve management outcomes. This article is part of the theme issue 'Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation'.

RevDate: 2019-07-29
CmpDate: 2019-07-29

Li SP, Tan J, Yang X, et al (2019)

Niche and fitness differences determine invasion success and impact in laboratory bacterial communities.

The ISME journal, 13(2):402-412.

There is increasing awareness of invasion in microbial communities worldwide, but the mechanisms behind microbial invasions remain poorly understood. Specifically, we know little about how the evolutionary and ecological differences between invaders and natives regulate invasion success and impact. Darwin's naturalization hypothesis suggests that the phylogenetic distance between invaders and natives could be a useful predictor of invasion, and modern coexistence theory proposes that invader-native niche and fitness differences combine to determine invasion outcome. However, the relative importance of phylogenetic distance, niche difference and fitness difference for microbial invasions has rarely been examined. By using laboratory bacterial microcosms as model systems, we experimentally assessed the roles of these differences for the success of bacterial invaders and their impact on native bacterial community structure. We found that the phylogenetic distance between invaders and natives failed to explain invasion success and impact for two of three invaders at the phylogenetic scale considered. Further, we found that invasion success was better explained by invader-native niche differences than relative fitness differences for all three invaders, whereas invasion impact was better explained by invader-native relative fitness differences than niche differences. These findings highlight the utility of considering modern coexistence theory to gain a more mechanistic understanding of microbial invasions.

RevDate: 2019-07-27

De Araujo LI, Karsten M, JS Terblanche (2019)

Exploring thermal flight responses as predictors of flight ability and geographic range size in Drosophila.

Comparative biochemistry and physiology. Part A, Molecular & integrative physiology pii:S1095-6433(19)30296-X [Epub ahead of print].

Thermal flight performance curves (TFPCs) may be a useful proxy for determining dispersal on daily timescales in winged insect species. Few studies have assessed TFPCs across a range of species under standard conditions despite that they may be useful in predicting variation in performance, abundance or geographic range shifts with forecast climate variability. Indeed, the factors determining realized dispersal within and among flying insect species are generally poorly understood. To better understand how flight performance may be correlated with geographic range extent and potential latitudinal climate variability, we estimated the thermal performance curves of flight ability in 11 Drosophilidae species (in 4 °C increments across 16-28 °C) after standard laboratory rearing for two generations. We tested if key morphological, evolutionary or ecological factors (e.g. species identity, sex, body mass, wing loading, geographic range size) predicted traits of TFPCs (including optimum temperature, maximum performance, thermal breadth of performance) or flight ability (success/failure to fly). Although several parameters of TFPCs varied among species these were typically not statistically significant probably owing to the relatively small pool of species assessed and the limited trait variation detected. The best explanatory model of these flight responses across species included significant positive effects of test temperature and wing area. However, the rank of geographic distribution breadth and phylogeny failed to explain significant variation in most of the traits, except for thermal performance breadth, of thermal flight performance curves among these 11 species. Future studies that employ a wider range of Drosophilidae species, especially if coupled with fine-scale estimates of species' environmental niches, would be useful.

RevDate: 2019-07-26

Guzzetti E, Salabery E, Ferriol P, et al (2019)

Oxidative stress induction by the invasive sponge Paraleucilla magna growing on Peyssonnelia squamaria algae.

Marine environmental research, 150:104763 pii:S0141-1136(19)30201-6 [Epub ahead of print].

The introduction of invasive species can lead to significant adverse effects on the colonized areas. The aim of the present research was to determine if the invasive behavior of Paraleucilla magna could induce the activation of the antioxidant defences in the native red algae, Peyssonnelia squamaria. Individuals of isolated P. squamaria and individuals epiphytized by P. magna, both growing on rocky bottoms, were collected. The activity of the antioxidant enzymes - catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase - and the levels of the malondialdehyde were significantly higher in the algae of the epiphytic group compared to the control group, while the detoxifying enzyme glutathione S-transferase did not show significant differences. The levels of reduced glutathione and total polyphenols were higher in the algae affected by the sponge. In conclusion, the arrival of the species P. magna induces an adaptative antioxidant response in P. squamaria determined by the use of biomarkers.

RevDate: 2019-07-26

Thomas JR, Masefield S, Hunt R, et al (2019)

Terrestrial emigration behaviour of two invasive crayfish species.

Behavioural processes pii:S0376-6357(19)30060-9 [Epub ahead of print].

To disperse between isolated waterbodies, freshwater organisms must often cross terrestrial barriers and many freshwater animals that are incapable of flight must rely on transport via flooding events, other animals or anthropogenic activity. Decapods such as crayfish, on the other hand, can disperse to nearby waterbodies by walking on land, a behaviour that has facilitated the spread of invasive species. Overland movement could play a key role in the management of non-native crayfish, though to what extent terrestrial emigration occurs in different species is poorly understood. Here, we directly compared the terrestrial emigration tendency of two non-native crayfish species in Great Britain; red swamp (Procambarus clarkii) and signal (Pacifastacus leniusculus) crayfish. We found that both species emigrated from the water and that there was no significant difference in terms of their terrestrial emigration tendency, suggesting that there is a risk both of these species will migrate overland and disperse to new habitats. This study shows that terrestrial emigration is an important behavioural trait to consider when preventing the escape of crayfish from aquaculture and further spread of invasive species.

RevDate: 2019-07-26

Liu M, Liao H, S Peng (2019)

Salt-tolerant native plants have greater responses to other environments when compared to salt-tolerant invasive plants.

Ecology and evolution, 9(13):7808-7818 pii:ECE35368.

The strong expansion potential of invasive plants is often attributed to fast adaptive responses to stress. However, the evolution of tolerance to one stressor may affect the responses to other stressors. Currently, it remains unclear what effect the evolution to one stressor might have on the responses to other single or combined stressors. Moreover, it is unknown how this might differ between invasive and native species.Invasive plants (Mikania micrantha and Bidens pilosa) and native plants (Merremia hederacea and Sida acuta) from low- and high-salinity habitats were grown under control and stressful conditions [salt stress, water stress (drought/waterlogging), and their combinations]. We explored the effects of evolved salt tolerance on the responses to water stress/combined stresses and the underlying trait mechanisms.The high-salinity populations of all species exhibited stronger salt tolerance than the low-salinity populations. As to the tolerance to other stressors, the high-salinity and low-salinity populations of the invasive species were similar, whereas the high-salinity populations of the native species exhibited stronger tolerance than the low-salinity populations under most stress treatments. However, the enhanced salt tolerance in native species was accompanied by reduced total biomass under control condition. The stress tolerance of native species correlated with leaf production rate and allocation to root, while the performance of native species under control condition correlated with leaf morphology and carbon assimilation rate. This suggests a trade-off between salt tolerance and performance in the native but not the invasive species, probably resulting from altered phenotypic/physiological traits.

Synthesis: Our work suggests that the evolution of tolerance to one stressor may have stronger effects on the tolerance to other stressors of the native compared with the invasive species. This may be a new paradigm to explain the greater advantage of invasive vs. native species in highly stressful habitats.

RevDate: 2019-07-26

Langdon B, Pauchard A, RO Bustamante (2019)

Acacia dealbata invasion in Chile: Surprises from climatic niche and species distribution models.

Ecology and evolution, 9(13):7562-7573 pii:ECE35295.

Aim: Tree invasions are a threat to biodiversity conservation, and although it is hard to predict the future spread of invasive tree species, there are tools available which could allow some estimations. The magnitude of spatial spread (a proxy of invasiveness) can be predicted from species climatic requirement (climatic niche) and can be represented by species distribution models (SDMs). We aimed to assess whether Acacia dealbata conserves its niche in the new environment of south-central Chile, and also, to estimate the invasive stage of the species.

Location: South-central area of Chile, between the O'Higgins (34°0″0'S) and Aysen Regions (47°0″0'S).

Methods: We used a combination of global, native, and regional data to improve the estimation of the potential distribution of A. dealbata, which has been considered one of the most invasive species of the genus, being registered in at least 34 countries in all the Continents.

Results: Our results show that A. dealbata does not conserve its niche in the study area, invading areas with climatic conditions different from those of the native range. It is also not at equilibrium with the environment. According to the global versus regional SDM comparisons, populations present in south-central Chile present different invasion stages. There are some stable populations, but there are other populations colonizing new areas, occupying unsuitable habitats and some of them are adapting to new climatic conditions. Climatic factors, such as precipitation seasonality, could be acting behind the expansion to new environments, and biotic factors or dispersal limitations could be preventing the species to colonize suitable areas.

Main conclusions: The invasion process of A. dealbata is far from stabilizing, and management options should focus on prevention, avoiding, for example, the introduction of the species to Patagonia where the species has not spread yet. More research is needed to complement our results and enhance the development of effective management strategies.

RevDate: 2019-07-26

Gonçalves RM, Mastrangelo T, Rodrigues JCV, et al (2019)

Invasion origin, rapid population expansion, and the lack of genetic structure of cotton bollworm (Helicoverpa armigera) in the Americas.

Ecology and evolution, 9(13):7378-7401 pii:ECE35123.

In 2013, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) was officially declared as present in Brazil and, after two years, the species was detected in the Caribbean and North America. Information on genetic features and accurate distribution of pests is the basis for agricultural protection policies. Furthermore, such knowledge is imperative to develop control strategies, understand the geographical range, and genetic patterns of this species in the Americas. Here, we carried out the widest sampling of H. armigera in the South American continent and Puerto Rico, after we estimated the diversity, demographic parameters, and genetic structure. The Internal Transcribed Spacer 1 (ITS1) nuclear marker was used to investigate the presence of putative hybrids between H. armigera and H. zea, and they were observed at a frequency of 1.5%. An ABC analysis, based in COI gene fragment, suggested Europe as the origin of South America specimens of H. armigeraand following a movement northward through the Caribbean. Three mtDNA genes and three nDNA markers revealed high genetic diversity distributed without the defined population structure of H. armigera in South America. Most of the genetic variation is within populations with a multidirectional expansion of H. armigera among morphoclimatic regions. High genetic diversity, rapid population expansion, and hybridization have implications for pest management since they suggest that adaptive alleles are spread through wide areas in South America that favor rapid local adaptation of H. armigera to new and disturbed environments (e.g., in agricultural areas).

RevDate: 2019-07-26

Marcantonio M, Winokur OC, CM Barker (2019)

Revisiting Alkali Metals As a Tool to Characterize Patterns of Mosquito Dispersal and Oviposition.

Insects, 10(8): pii:insects10080220.

Mark-recapture methods constitute a set of classical ecological tools that are used to collect information on species dispersal and population size. These methods have advanced knowledge in disparate scientific fields, from conservation biology to pest control. Gathering information on the dispersal of mosquito species, such as Aedes aegypti, has become critical since the recognition of their role as vectors of pathogens. Here, we evaluate a method to mark mosquitoes that exploits the rare alkali metals rubidium (Rb) and caesium (Cs), which have been used previously to mark adult insects through feeding. We revised this method by adding Rb and Cs directly to water in which the immature stages of Ae. aegypti were allowed to develop. We then assessed the effect of Rb- and Cs-enriched water on fitness, survival and bioaccumulation in both adult females and their eggs. Results indicated that Cs had adverse effects on Ae. aegypti, even at low concentrations, whereas Rb at low concentrations had no measured effects on exposed individuals and accumulated at detectable levels in adult females. The method described here relies on passive uptake of Rb during immature stages, which has the benefit of avoiding handling or manipulation of the dispersive adults, which enables purer measurement of movement. Moreover, we demonstrated that Rb was transferred efficiently from the marked females to their eggs. To our knowledge, Rb is the only marker used for mosquitoes that has been shown to transfer vertically from females to eggs. The application of Rb rather than more traditional markers may therefore increase the quality (no impact on released individuals) and quantity (both adults and eggs are marked) of data collected during MR studies. The method we propose here can be used in combination with other markers, such as stable isotopes, in order to maximize the information collected during MR experiments.

RevDate: 2019-07-25

Dobigny G, Gauthier P, Houéménou G, et al (2019)

Spatio-temporal survey of small mammal-borne Trypanosoma lewisi in Cotonou, Benin, and the potential risk of human infection.

Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases pii:S1567-1348(19)30185-6 [Epub ahead of print].

Human trypanosomoses are the sleeping sickness in Africa and Chagas disease in Latin America. However, atypical human infections by animal trypanosomes have been described, but poorly investigated. Among them, the supposed rat-specific T. lewisi was shown to be responsible for a few severe cases. In Africa, the scarcity of data and the null awareness about the atypical human trypanosomoses suggest that the number of cases may be higher that currently thought. Furthermore, T. lewisi is resistant to normal human serum and therefore a potential human pathogen. In order to document T. lewisi distribution and ecology, a qPCR- and 16DNA sequencing-based survey was conducted in 369 rodents from three urban districts of Cotonou city, Benin, during three different periods of the same year. Our study demonstrated very high prevalence (57.2%) even when considering only individuals identified as positive through DNA sequencing (39.2%). Black rats represented the most dominant as well as the most T. lewisi-parasitized species. No difference was retrieved neither between seasons nor districts, suggesting a large infestation of rodents by trypanosomes throughout the year and the city. Our results suggest that conditions are gathered for rat to human transmission of T. lewisi in these socio-environmentally degraded urban areas, thus pointing towards the rapidly urbanizing Abidjan-Lagos corridor as a region at particular risk.

RevDate: 2019-07-25

DeGolia AH, Hiroyasu EHT, SE Anderson (2019)

Economic losses or environmental gains? Framing effects on public support for environmental management.

PloS one, 14(7):e0220320 pii:PONE-D-19-04840.

Environmental managers face major challenges related to project implementation and communicating the significance of those projects to the public. Effective communication can mitigate public opposition or increase support for specific projects and increase public and political support for environmental management more generally. In this study, we evaluate which types of benefits or losses environmental managers should communicate and how to frame those attributes to achieve greater public support. To do so, we field a survey experiment that presents the benefits of an invasive species management project, utilizing a two (economic, ecological) by two (gain, loss) factorial design as well as a control message. Ecological messages lead to significantly more support for invasive species management than economic messages, and loss frames are more effective than gain frames. We also find that treatment responses differ across several covariates including political ideology and environmentalism. These results indicate that the public is more concerned with managing invasive species for intrinsic environmental worth than economic benefit and that preventing further environmental degradation is more motivating than promoting additional environmental gains.

RevDate: 2019-07-25

García-Fernández A, Manzano P, Seoane J, et al (2019)

Herbivore corridors sustain genetic footprint in plant populations: a case for Spanish drove roads.

PeerJ, 7:e7311 pii:7311.

Habitat fragmentation is one of the greatest threats to biodiversity conservation and ecosystem productivity mediated by direct human impact. Its consequences include genetic depauperation, comprising phenomena such as inbreeding depression or reduction in genetic diversity. While the capacity of wild and domestic herbivores to sustain long-distance seed dispersal has been proven, the impact of herbivore corridors in plant population genetics remains to be observed. We conducted this study in the Conquense Drove Road in Spain, where sustained use by livestock over centuries has involved transhumant herds passing twice a year en route to winter and summer pastures. We compared genetic diversity and inbreeding coefficients of Plantago lagopus populations along the drove road with populations in the surrounding agricultural matrix, at varying distances from human settlements. We observed significant differences in coefficients of inbreeding between the drove road and the agricultural matrix, as well as significant trends indicative of higher genetic diversity and population nestedness around human settlements. Trends for higher genetic diversity along drove roads may be present, although they were only marginally significant due to the available sample size. Our results illustrate a functional landscape with human settlements as dispersal hotspots, while the findings along the drove road confirm its role as a pollinator reservoir observed in other studies. Drove roads may possibly also function as linear structures that facilitate long-distance dispersal across the agricultural matrix, while local P. lagopus populations depend rather on short-distance seed dispersal. These results highlight the role of herbivore corridors for conserving the migration capacity of plants, and contribute towards understanding the role of seed dispersal and the spread of invasive species related to human activities.

RevDate: 2019-07-25

Kong JY, Yeon SC, Lee HJ, et al (2019)

Protective Effects of Nutria Bile against Thioacetamide-Induced Liver Injury in Mice.

Evidence-based complementary and alternative medicine : eCAM, 2019:6059317.

Several eradication programs have been developed and executed to curb alien invasive species that tend to damage the ecological environments they colonize; however, only few studies have evaluated the utilization of carcasses of these species after eradication. Nutria (Myocastor coypus) is an invasive rodent species targeted by eradication programs in many countries. We noted that nutria produce large amounts of ursodeoxycholic acid (UDCA) in their bile. UDCA is a unique component responsible for the anti-inflammatory and hepatoprotective effects exerted by bear bile. Therefore, we sought to examine the medicinal utility of nutria carcasses by investigating the hepatoprotective effect of their bile in mice. C57BL/6 mice were injected with thioacetamide (TAA), which induced liver damage by increasing Kupffer cell infiltration. Administration of nutria bile reduced hepatic inflammation, improved hepatic function, and increased the levels of senescence marker protein 30 (an indicator of hepatocyte viability). Our results show that nutria bile exerts protective effects against TAA-induced liver injury in mice, suggesting that nutria carcasses may be used for the treatment of liver injuries.

RevDate: 2019-07-24

Jourdan J, Piro K, Weigand A, et al (2019)

Small-scale phenotypic differentiation along complex stream gradients in a non-native amphipod.

Frontiers in zoology, 16:29 pii:327.

Background: Selective landscapes in rivers are made up by an array of selective forces that vary from source to downstream regions or between seasons, and local/temporal variation in fitness maxima can result in gradual spatio-temporal variation of phenotypic traits. This study aimed at establishing freshwater amphipods as future model organisms to study adaptive phenotypic diversification (evolutionary divergence and/or adaptive plasticity) along stream gradients.

Methods: We collected Gammarus roeselii from 16 sampling sites in the Rhine catchment during two consecutive seasons (summer and winter). Altogether, we dissected n = 1648 individuals and quantified key parameters related to morphological and life-history diversification, including naturally selected (e.g., gill surface areas) as well as primarily sexually selected traits (e.g., male antennae). Acknowledging the complexity of selective regimes in streams and the interrelated nature of selection factors, we assessed several abiotic (e.g., temperature, flow velocity) and biotic ecological parameters (e.g., conspecific densities, sex ratios) and condensed them into four principal components (PCs).

Results: Generalized least squares models revealed pronounced phenotypic differentiation in most of the traits investigated herein, and components of the stream gradient (PCs) explained parts of the observed differences. Depending on the trait under investigation, phenotypic differentiation could be ascribed to variation in abiotic conditions, anthropogenic disturbance (influx of thermally polluted water), or population parameters. For example, female fecundity showed altitudinal variation and decreased with increasing conspecific densities, while sexual dimorphism in the length of male antennae-used for mate finding and assessment-increased with increasing population densities and towards female-biased sex ratios.

Conclusions: We provide a comprehensive protocol for comparative analyses of intraspecific variation in life history traits in amphipods. Whether the observed phenotypic differentiation over small geographical distances reflects evolutionary divergence or plasticity (or both) remains to be investigated in future studies. Independent of the mechanisms involved, variation in several traits is likely to have consequences for ecosystem functions. For example, leaf-shredding in G. roeselii strongly depends on body size, which varied in dependence of several ecological parameters.

RevDate: 2019-07-24

Idrissou FO, Huang Q, Yañez O, et al (2019)

International beeswax trade facilitates small hive beetle invasions.

Scientific reports, 9(1):10665 pii:10.1038/s41598-019-47107-6.

International trade can facilitate biological invasions, but the possible role of beeswax trade for small hive beetles (SHBs), Aethina tumida Murray (Coleoptera: Nitidulidae) is poorly understood. SHBs are parasites of social bee colonies native to sub-Saharan Africa and have become an invasive species. Since 1996, SHBs have established in all continents except Antarctica. Here, we combine mitochondrial DNA analyses (COI gene, N = 296 SHBs, 98 locations) with previously published beeswax trade data (FAO) for 12 confirmed SHB invasions. Our genetic data confirm previous findings and suggest novel SHB African origins. In nine out of 12 invasion cases, the genetic and beeswax trade data match. When excluding one confirmed pathway (bee imports) and two cases, for which no FAO data were available, the genetics and beeswax trade data consistently predict the same source. This strongly suggests that beeswax imports from Ethiopia, South Africa, Tanzania and the USA, respectively, have mainly been responsible for the past invasion success of this beetle species. Adequate mitigation measures should be applied to limit this key role of beeswax imports for the further spread of SHBs. Combining genetics with trade data appears to be a powerful tool to better understand and eventually mitigate biological invasions.

RevDate: 2019-07-23

Tarter KD, Levy CE, Yaglom HD, et al (2019)

USING CITIZEN SCIENCE TO ENHANCE SURVEILLANCE OF AEDES AEGYPTI IN ARIZONA, 2015-17.

Journal of the American Mosquito Control Association, 35(1):11-18.

Vector surveillance is an essential component of vector-borne disease prevention, but many communities lack resources to support extensive surveillance. The Great Arizona Mosquito Hunt (GAMH) was a collaborative citizen science project conducted during 2015-17 to enhance surveillance for Aedes aegypti in Arizona. Citizen science projects engage the public in scientific research in order to further scientific knowledge while improving community understanding of a specific field of science and the scientific process. Participating schools and youth organizations across the state conducted oviposition trapping for 1-4 wk during peak Ae. aegypti season in Arizona and returned the egg sheets to collaborating entomologists for identification. During the 3-year program, 120 different schools and youth organizations participated. Few participants actually collected Aedes eggs in their traps in 2015 or 2017, but about one-third of participants collected eggs during 2016, including 3 areas that were not previously reported to have Ae. aegypti. While relatively few new areas of Ae. aegypti activity were identified, GAMH was found to be a successful method of engaging citizen scientists. Future citizen science mosquito surveillance projects might be useful to further define the ecology and risk for vector-borne diseases in Arizona.

RevDate: 2019-07-23

Thiébaut G, Tarayre M, H Rodríguez-Pérez (2019)

Allelopathic Effects of Native Versus Invasive Plants on One Major Invader.

Frontiers in plant science, 10:854.

Allelopathy is defined as the effects (stimulatory and inhibitory) of a plant on the development of neighboring plants through the release of secondary compounds. Autoallelophaty is the beneficial or harmful effect of a plant species on itself. The allelopathic potential belonging to a native species could induce a biotic resistance against invasive plants, whereas allelochemicals released by exotic species could favor the establishment of invasive species (invasional meltdown). The aim of our study was to examine the potential allelopathic effect of four plant species on the target species Ludwigia hexapetala using two experiments. In the first experiment, we tested the allelopathic effect of root and leaf leachates of the two congeneric exotic species Ludwigia hexapetala and Ludwigia peploides on L. hexapetala, while in the second experiment, we studied the allelopathic effect of root and leaf leachates of a sympatric exotic species Myriophyllum aquaticum and of one native species Mentha aquatica on L. hexapetala. We measured the stem length to calculate the relative growth rate and four physiological traits (nitrogen balance index and flavonol, chorophyll, anthocyanin indices) of the target plants on a weekly basis. At the end of the experiment, we determined the aboveground and belowground biomass. We also counted the number of lateral branches and measured their lengths. We found that the root leachates of L. peploides and of Myriophyllum aquaticum had stimulated the synthesis of flavonols of L. hexapetala. Leaf leachate of L. hexapetala also stimulated its own flavonol synthesis. Also, the root leachate of L. peploides had stimulated the total biomass and length of lateral branches of L. hexapetala, whereas the production of lateral branches had been stimulated by root leachates of both Ludwigia species and by leaf leachate of Myriophyllum aquaticum. The autoallelopathy of L. hexapetala could explain its invasiveness. Both leachates produced by Mentha aquatica had no effect on the physiological and morphological traits of the invasive L. hexapetala and indicated no biotic resistance in the recipient community. The two invasive plant species Myriophyllum aquaticum and L. peploides could favor the establishment of L. hexapetala. These results suggested an "invasional meltdown."

RevDate: 2019-07-23

Bertoldi V, Rondoni G, Brodeur J, et al (2019)

An Egg Parasitoid Efficiently Exploits Cues From a Coevolved Host But Not Those From a Novel Host.

Frontiers in physiology, 10:746.

Egg parasitoids have evolved adaptations to exploit host-associated cues, especially oviposition-induced plant volatiles and odors of gravid females, when foraging for hosts. The entire host selection process is critical for successful parasitism and relevant in defining host specificity of parasitoids. We hypothesized that naïve egg parasitoid females reared on their coevolved host are able to exploit cues related to the coevolved host but not those from a novel host. We used the egg parasitoid Trissolcus japonicus, its coevolved host Halyomorpha halys, and the non-coevolved host Podisus maculiventris to evaluate this hypothesis. H. halys, a polyphagous pest native from Eastern Asia, has invaded North America and Europe, resulting in serious damage to crops. T. japonicus is the most effective egg parasitoid of H. halys in its native area and thus considered a major candidate for biological control. This parasitoid was detected in North America and Europe as a result of accidental introductions. Laboratory host range of T. japonicus includes P. maculiventris, an American predatory stink bug used as a biological control agent of several pests. Using T. japonicus reared on its natural host H. halys, we tested in a Y-tube olfactometer the responses of naïve parasitoid females to volatiles from tomato plants with a deposited egg mass and feeding punctures of either H. halys or P. maculiventris. Additionally, using two different olfactometer set-ups, we tested T. japonicus responses to volatiles emitted by eggs and mature males and females of H. halys or P. maculiventris. Tomato plants subjected to oviposition and feeding by H. halys were preferred by the wasp compared to clean plants, suggesting a possible activation of an indirect defense mechanism. Furthermore, T. japonicus females were attracted by cues from gravid females and mature males of H. halys but not from eggs. By contrast, naïve parasitoid females never responded to cues associated with P. maculiventris, although this non-target host is suitable for complete parasitoid development. Such lack of responses might reduce the probability of T. japonicus locating and parasitizing P. maculiventris under field conditions. Our experimental approach properly simulates the parasitoid host-location process and could be combined with the required host specificity tests for risk assessment in biological control programs.

RevDate: 2019-07-23

Rivera B, Cook K, Andrews K, et al (2019)

Pathogen Dynamics in an Invasive Frog Compared to Native Species.

EcoHealth pii:10.1007/s10393-019-01432-4 [Epub ahead of print].

Emerging infectious diseases threaten the survival of wildlife populations and species around the world. In particular, amphibians are experiencing population declines and species extinctions primarily in response to two pathogens, the fungus Batrachochytrium dendrobatidis (Bd) and the iridovirus Ranavirus (Rv). Here, we use field surveys and quantitative (q)PCR to compare infection intensity and prevalence of Bd and Rv across species and seasons on Jekyll Island, a barrier island off the coast of Georgia, USA. We collected oral and skin swabs for 1 year from four anuran species and three families, including two native hylids (Hyla cinerea and Hyla squirella), a native ranid (Rana sphenocephala), and the invasive rain frog Eleutherodactylus planirostris. Bd infection dynamics did not vary significantly over sampling months, but Rv prevalence and intensity were significantly higher in fall 2014 compared to spring 2015. Additionally, Rv prevalence and intensity were significantly higher in E. planirostris than in the other three species. Our study highlights the potential role of invasive amphibians as drivers of disease dynamics and demonstrates the importance of pathogen surveillance across multiple time periods and species to accurately capture the infectious disease landscape.

RevDate: 2019-07-23
CmpDate: 2019-07-23

González E, Sher AA, Anderson RM, et al (2017)

Vegetation response to invasive Tamarix control in southwestern U.S. rivers: a collaborative study including 416 sites.

Ecological applications : a publication of the Ecological Society of America, 27(6):1789-1804.

Most studies assessing vegetation response following control of invasive Tamarix trees along southwestern U.S. rivers have been small in scale (e.g., river reach), or at a regional scale but with poor spatial-temporal replication, and most have not included testing the effects of a now widely used biological control. We monitored plant composition following Tamarix control along hydrologic, soil, and climatic gradients in 244 treated and 172 reference sites across six U.S. states. This represents the largest comprehensive assessment to date on the vegetation response to the four most common Tamarix control treatments. Biocontrol by a defoliating beetle (treatment 1) reduced the abundance of Tamarix less than active removal by mechanically using hand and chain-saws (2), heavy machinery (3) or burning (4). Tamarix abundance also decreased with lower temperatures, higher precipitation, and follow-up treatments for Tamarix resprouting. Native cover generally increased over time in active Tamarix removal sites, however, the increases observed were small and was not consistently increased by active revegetation. Overall, native cover was correlated to permanent stream flow, lower grazing pressure, lower soil salinity and temperatures, and higher precipitation. Species diversity also increased where Tamarix was removed. However, Tamarix treatments, especially those generating the highest disturbance (burning and heavy machinery), also often promoted secondary invasions of exotic forbs. The abundance of hydrophytic species was much lower in treated than in reference sites, suggesting that management of southwestern U.S. rivers has focused too much on weed control, overlooking restoration of fluvial processes that provide habitat for hydrophytic and floodplain vegetation. These results can help inform future management of Tamarix-infested rivers to restore hydrogeomorphic processes, increase native biodiversity and reduce abundance of noxious species.

RevDate: 2019-07-22

Makkonen J, Kokko H, Gökmen G, et al (2019)

The signal crayfish (Pacifastacus leniusculus) in Lake Tahoe (USA) hosts multiple Aphanomyces species.

Journal of invertebrate pathology pii:S0022-2011(19)30027-8 [Epub ahead of print].

The genus Aphanomyces (Oomycetes) comprises approximately 50 known species of water molds in three lineages. One of the most notorious is Aphanomyces astaci, the causative agent of crayfish plague. In this study, fresh isolates of Aphanomyces astaci were collected from 20 live specimens of the signal crayfish Pacifastacus leniusculus (Dana, 1852) from Lake Tahoe, California, providing 35 axenic cultures of A. astaci as well as two apparently undescribed Aphanomyces spp. isolates. Based on the results of ITS-, chitinase-, mitochondrial rnnS- and rnnL-sequences and microsatellite markers combined, the Lake Tahoe A. astaci isolates were identical to isolates of A. astaci B-haplogroup commonly detected in Europe, and infection experiments confirmed their high virulence towards noble crayfish. One of the two undescribed Aphanomyces spp. isolates was highly similar to an Aphanomyces lineage detected previously in crustacean zooplankton (Daphnia) in Central Europe, while the other was distinct and most closely related (ITS sequence similarity of 93%) to either A. astaci or to Aphanomyces fennicus isolated recently from Astacus astacus in Finland. Neither of the two Aphanomyces spp. isolates caused crayfish mortality under experimental conditions. Our results indicate that the populations of North American signal crayfish can act as carriers of both pathogenic and non-pathogenic Aphanomyces at the same time. Furthermore, considering that a limited number of crayfish individuals from a single location yielded multiple distinct Aphanomyces isolates, our results suggest that substantial species diversity within this genus remains undescribed.

RevDate: 2019-07-22

Kamiyama MT, C Guédot (2019)

Varietal and Developmental Susceptibility of Tart Cherry (Rosales: Rosaceae) to Drosophila suzukii (Diptera: Drosophilidae).

Journal of economic entomology pii:5480701 [Epub ahead of print].

Drosophila suzukii (Matsumura) is an invasive species of vinegar fly that infests soft-skinned and stone fruits. Since its first detection in the United States, D. suzukii has become a prominent economic threat in fruit crop industries, particularly affecting caneberry and sweet cherry growers. This study examined the susceptibility of tart cherries (Prunus cerasus) to D. suzukii and sampled for larvae and adult D. suzukii during the tart cherry growing season. Four tart cherry cultivars (Montmorency, Balaton, Carmine Jewel, and Kántorjánosi) were tested at three different ripeness stages (unripe, ripening, and ripe), in no-choice laboratory bio-assays. Field monitoring and sampling revealed that first adult D. suzukii detection occurred on 16 June, and first field larval D. suzukii detection occurred on 28 July. Adult D. suzukii populations increased through late August, and high numbers of adults overlapped with the tart cherry harvest. Lab assays indicated that tart cherry cultivars generally became more susceptible to D. suzukii as they ripened. As the fruit developed, °Brix (sugar content) increased and firmness generally decreased. Tart cherry °Brix and firmness were not correlated with the number of D. suzukii eggs per gram of fruit, but showed a significant interaction effect with the number of larvae and adults per gram of fruit. This study shows that tart cherries are largely not susceptible to D. suzukii when unripe and become susceptible as soon as the fruits change color, suggesting that fruits should be protected as soon as they begin to ripen and D. suzukii populations begin to rise.

RevDate: 2019-07-22

Puterka GJ, Hammon RW, Franklin M, et al (2019)

Distribution of a New Invasive Species, Sipha maydis (Heteroptera: Aphididae), on Cereals and Wild Grasses in the Southern Plains and Rocky Mountain States.

Journal of economic entomology pii:5436903 [Epub ahead of print].

Sipha maydis Passerini (Heteroptera: Aphididae) is a cereal pest with an extensive geographical range that includes countries in Europe, Asia, Africa, and South America. Reports of S. maydis in the United States have been infrequent since it was first detected in California, 2007. Two studies, focused (NW CO) and multistate (OK, TX, NM, CO, UT, WY), were conducted to determine the distribution and host range of S. maydis in the Rocky Mountain and Southern Plains states over a 3-yr period, 2015-2017. In 2015, focused sampling in NW Colorado found S. maydis at 59% of the 37 sites, primarily on wheat. Sipha maydis did not survive extreme winter temperatures from late December 2015 to early January 2016 that ranged from -9.0 to -20.9°C over a 9-d period, which resulted in no aphids detected in 2016. In the multistate study, S. maydis occurred in 14.6% of 96 sites sampled in 2015, 8% of 123 sites in 2016, and 9% of 85 sites in 2017 at wide range of altitudes from 1,359 to 2,645 m. Sipha maydis occurred mainly in NW and SW Colorado and NE New Mexico along with a few sites in NE Colorado, SE Utah, and SE Wyoming. This aphid mainly infested wheat followed by a variety of eight wild grass species. No parasites, predators, sexual morphs, or significant plant damage occurred at the sites. Sipha maydis utilized 14 hosts in the United States including 8 new host records, which expands its host range to 52 plant species worldwide. Sipha maydis may be of concern to wheat, barley, and sorghum production in the United States if its populations continue to increase.

RevDate: 2019-07-22
CmpDate: 2019-07-22

Boiffin J, Badeau V, N Bréda (2017)

Species distribution models may misdirect assisted migration: insights from the introduction of Douglas-fir to Europe.

Ecological applications : a publication of the Ecological Society of America, 27(2):446-457.

Species distribution models (SDMs), which statistically relate species occurrence to climatic variables, are widely used to identify areas suitable for species growth under future climates and to plan for assisted migration. When SDMs are projected across times or spaces, it is assumed that species climatic requirements remain constant. However, empirical evidence supporting this assumption is rare, and SDM predictions could be biased. Historical human-aided movements of tree species can shed light on the reliability of SDM predictions in planning for assisted migration. We used Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), a North American conifer introduced into Europe during the mid-19th century, as a case-study to test niche conservatism. We combined transcontinental data sets of Douglas-fir occurrence and climatic predictors to compare the realized niches between native and introduced ranges. We calibrated a SDM in the native range and compared areas predicted to be climatically suitable with observed presences. The realized niches in the native and introduced ranges showed very limited overlap. The SDM calibrated in North America had very high predictive power in the native range, but failed to predict climatic suitability in Europe where Douglas-fir grows in climates that have no analogue in the native range. We review the ecological mechanisms and silvicultural practices that can trigger such shifts in realized niches. Retrospective analysis of tree species introduction revealed that the assumption of niche conservatism is erroneous. As a result, distributions predicted by SDM are importantly biased. There is a high risk that assisted migration programs may be misdirected and target inadequate species or introduction zones.

RevDate: 2019-07-20

Hohenadler MAA, Nachev M, Freese M, et al (2019)

How Ponto-Caspian invaders affect local parasite communities of native fish.

Parasitology research pii:10.1007/s00436-019-06399-3 [Epub ahead of print].

Invasive species are a major threat to ecosystems worldwide. Their effects are versatile and mostly well studied. However, not much is known about the impact of invasion on native parasite communities, although parasites are usually important response variables for ecosystem health. To improve the knowledge on how native fish parasite communities and their dynamics are affected by invasive species and how these processes change local host-parasite interactions over time, we studied different host-parasite systems in four German rivers. Three of these rivers (Rhine, Ems, and Elbe) are heavily invaded by different Ponto-Caspian species such as the amphipod Dikerogammarus villosus and various gobiids such as Neogobius melanostomus and Ponticola kessleri that serve as potential hosts for different local parasite species, while the fourth river (Schwentine) was free of any Ponto-Caspian invaders. Due to the lack of additional uninvaded river systems, literature data on parasite communities before invasion were compared with the post invasion status for the rivers Rhine and Elbe. The results showed differences among the parasite communities of different host species from the three invaded rivers when compared to the Schwentine River. Among the local internal parasite communities, especially the acanthocephalan Pomphorhynchus laevis and the nematode Raphidascaris acus have to be considered as key species associated with invasions from the Ponto-Caspian region. As the examined invasive Ponto-Caspian fish species serves as suitable host for both parasite species, the increases in their infection rates in native fish species are examples of parasite spill back (R. acus) and spill over (P. laevis, at least in the river Rhine). These results were further supported by the analysis of literature data on parasite communities of the past 20 years. Consequences for local parasite communities range from decreased prevalence of native parasites towards an extinction of entire parasite species.

RevDate: 2019-07-20

Liu G, Tang H, Fan J, et al (2019)

Removal of 2,4,6-trichlorophenol from water by Eupatorium adenophorum biochar-loaded nano-iron/nickel.

Bioresource technology, 289:121734 pii:S0960-8524(19)30964-2 [Epub ahead of print].

From the perspective of waste utilization, the invasive species, Eupatorium adenophorum was used to prepare biochar, which was then loaded with iron/nickel bimetals. Compared with pure biochar, the biochar-loaded nano-iron/nickel bimetals have a significant effect on the removal of 2,4,6-trichlorophenol (2,4,6-TCP) from water, and their degradation rate can be increased by 39.7%-71.6% under different conditions. Several factors can influence the removal of 2,4,6-TCP, including the load ratio, pH of the solution, concentration of 2,4,6-TCP, and coexisting ions in water (HCO3-, SO42-, NO3-). Based on the density functional model (DET), Ni can activate H2 (produced in the reaction between nano-Fe and H2O) to convert to H*, which can then substitute Cl. The activation energy is 109.5 kJ/mol, indicating the reaction is easy to take place.

RevDate: 2019-07-19

Mcgeoch MA, Latombe G, Andrew NR, et al (2019)

Measuring continuous compositional change using decline and decay in zeta diversity.

Ecology [Epub ahead of print].

Incidence, or compositional, matrices are generated for a broad range of research applications in biology. Zeta diversity provides a common currency and conceptual framework that links incidence-based metrics with multiple patterns of interest in biology, ecology and biodiversity science. It quantifies the variation in species (or OTU) composition of multiple assemblages (or cases) in space or time, to capture the contribution of the full suite of narrow, intermediate and wide-ranging species to biotic heterogeneity. Here we provide a conceptual framework for the application and interpretation of patterns of continuous change in compositional diversity using zeta diversity. This includes consideration of the survey design context, and the multiple ways in which zeta diversity decline and decay can be used to examine and test turnover in the identity of elements across space and time. We introduce the zeta ratio-based retention rate curve to quantify rates of compositional change. We illustrate these applications using 11 empirical datasets from a broad range of taxa, scales and levels of biological organisation - from DNA molecules and microbes to communities and interaction networks - including one of the original data sets used to express compositional change and distance decay in ecology. We show (i) how different sample selection schemes used during the calculation of compositional change are appropriate for different data types and questions, (ii) how higher orders of zeta may in some cases better detect shifts and transitions, and (iii) the relative roles of rare versus common species in driving patterns of compositional change. By exploring the application of zeta diversity decline and decay, including the retention rate, across this broad range of contexts, we demonstrate its application for understanding continuous turnover in biological systems. This article is protected by copyright. All rights reserved.

RevDate: 2019-07-19

Cheng D, Chen S, Huang Y, et al (2019)

Symbiotic microbiota may reflect host adaptation by resident to invasive ant species.

PLoS pathogens, 15(7):e1007942 pii:PPATHOGENS-D-18-02136 [Epub ahead of print].

Exotic invasive species can influence the behavior and ecology of native and resident species, but these changes are often overlooked. Here we hypothesize that the ghost ant, Tapinoma melanocephalum, living in areas that have been invaded by the red imported fire ant, Solenopsis invicta, displays behavioral differences to interspecific competition that are reflected in both its trophic position and symbiotic microbiota. We demonstrate that T. melanocephalum workers from S. invicta invaded areas are less aggressive towards workers of S. invicta than those inhabiting non-invaded areas. Nitrogen isotope analyses reveal that colonies of T. melanocephalum have protein-rich diets in S. invicta invaded areas compared with the carbohydrate-rich diets of colonies living in non-invaded areas. Analysis of microbiota isolated from gut tissue shows that T. melanocephalum workers from S. invicta invaded areas also have different bacterial communities, including a higher abundance of Wolbachia that may play a role in vitamin B provisioning. In contrast, the microbiota of workers of T. melanocephalum from S. invicta-free areas are dominated by bacteria from the orders Bacillales, Lactobacillales and Enterobacteriales that may be involved in sugar metabolism. We further demonstrate experimentally that the composition and structure of the bacterial symbiont communities as well as the prevalence of vitamin B in T. melanocephalum workers from S. invicta invaded and non-invaded areas can be altered if T. melanocephalum workers are supplied with either protein-rich or carbohydrate-rich food. Our results support the hypothesis that bacterial symbiont communities can help hosts by buffering behavioral changes caused by interspecies competition as a consequence of biological invasions.

RevDate: 2019-07-19

Escobar-Correas S, Mendoza-Porras O, Dellagnola F, et al (2019)

Integrative proteomic analysis of digestive tract glycosidases from the invasive golden apple snail, Pomacea canaliculata.

Journal of proteome research [Epub ahead of print].

The freshwater snail Pomacea canaliculata, an invasive species of global significance, possesses a well-developed digestive system and diverse feeding mechanisms enabling the intake of a wide variety of food. The identification of glycosidases in adult snails would increase the understanding of their digestive physiology and potentially generate new opportunities to eradicate and/or control this invasive species. In this study, liquid chromatography coupled to tandem mass spectrometry was applied to define the occurrence, diversity, and origin of glycoside hydrolases along the digestive tract of P. canaliculata. A range of cellulases, hemicellulases, amylases, maltases, fucosidases, and galactosidases were identified across the digestive tract. The digestive gland and the contents of the crop and style sac yield a higher diversity of glycosidase-derived peptides. Subsequently, peptides derived from 81 glycosidases (46 proteins from the public database and 35 uniquely from the transcriptome database) that were distributed amongst 13 glycoside hydrolase families were selected and quantified using multiple reaction monitoring mass spectrometry. This study showed a high glycosidase abundance and diversity in the gut contents of P. canaliculata which participate in extracellular digestion of complex dietary carbohydrates. Salivary and digestive glands were the main tissues involved in their synthesis and secretion.

RevDate: 2019-07-19

Abril S, C Gómez (2019)

Factors triggering queen executions in the Argentine ant.

Scientific reports, 9(1):10427 pii:10.1038/s41598-019-46972-5.

Competition among queens in polygynous societies may result in queen executions or conflicts over personal reproduction. Understanding the factors that mediate the executions of ant queens should provide insight into how queen numbers are regulated in polygynous insect societies. The Argentine ant is a widespread invasive species that displays secondary polygyny, and workers execute 90% of their nestmate queens each spring. In this study, we investigated: (1) whether ambient temperature, queen number, and protein deprivation have an effect on queen executions and (2) whether workers select the queens slated for execution based on their cuticular hydrocarbon (CHC) profiles. We found that the percentage of queens executed was positively correlated with temperature and queen number but that protein deprivation did not play a role. As for queen fate, the levels of some CHCs were higher in surviving queens. One of these CHCs is associated with queen productivity (i.e egg-laying rate and ovarian index) suggesting that workers execute the least productive queens. Our findings suggest that chemical cues related to fertility signaling may mediate queen executions in Argentine ants.

RevDate: 2019-07-19
CmpDate: 2019-07-19

Benucci GMN, Bonito V, G Bonito (2019)

Fungal, Bacterial, and Archaeal Diversity in Soils Beneath Native and Introduced Plants in Fiji, South Pacific.

Microbial ecology, 78(1):136-146.

The Fiji Islands is an archipelago of more than 330 islands located in the tropics of the South Pacific Ocean. Microbial diversity and biogeography in this region is still not understood. Here, we present the first molecular characterization of fungal, bacterial, and archaeal communities in soils from different habitats within the largest Fijian island, Viti Levu. Soil samples were collected from under native vegetation in maritime-, forest-, stream-, grassland-, and casuarina-dominated habitats, as well as from under the introduced agricultural crops sugarcane, cassava, pine, and mahogany. Soil microbial diversity was analyzed through MiSeq amplicon sequencing of 16S (for prokaryotes), ITS, LSU ribosomal DNA (for fungi). Prokaryotic communities were dominated by Proteobacteria (~ 25%), Acidobacteria (~ 19%), and Actinobacteria (~ 17%), and there were no indicator species associated with particular habitats. ITS and LSU were congruent in β-diversity patterns of fungi, and fungal communities were dominated by Ascomycota (~ 57-64%), followed by Basidiomycota (~ 20-23%) and Mucoromycota (~ 10%) according to ITS, or Chytridiomycota (~ 9%) according to LSU. Indicator species analysis of fungi found statistical associations of Cenococcum, Wilcoxina, and Rhizopogon to Pinus caribaea. We hypothesize these obligate biotrophic fungi were co-introduced with their host plant. Entoloma was statistically associated with grassland soils, and Fusarium and Lecythophora with soils under cassava. Observed richness varied from 65 (casuarina) to 404 OTUs (cassava) for fungi according to ITS region, and from 1268 (pine) to 2931 OTUs (cassava) for bacteria and archaea. A major finding of this research is that nearly 25% of the fungal OTUs are poorly classified, indicative of novel biodiversity in this region. This preliminary survey provides important baseline data on fungal, bacterial, and archaeal diversity and biogeography in the Fiji Islands.

RevDate: 2019-07-19
CmpDate: 2019-07-19

Tamate S, Iwasaki WM, Krysko KL, et al (2017)

Inferring evolutionary responses of Anolis carolinensis introduced into the Ogasawara archipelago using whole genome sequence data.

Scientific reports, 7(1):18008.

Invaded species often can rapidly expand and establish in novel environments through adaptive evolution, resulting in devastating effects on native communities. However, it is unclear if genetic variation at whole-genomic levels is actually reduced in the introduced populations and which genetic changes have occurred responding to adaptation to new environments. In the 1960s, Anolis carolinensis was introduced onto one of the Ogasawara Islands, Japan, and subsequently expanded its range rapidly throughout two of the islands. Morphological comparison showed that lower hindlimb length in the introduced populations tended to be longer than those in its native Florida populations. Using re-sequenced whole genomic data, we estimated that the effective population size at the time of introduction was actually small (less than 50). We also inferred putative genomic regions subject to natural selection after this introduction event using SweeD and a method based on Tajima's D, π and F ST . Five candidate genes that were potentially subject to selection were estimated by both methods. The results suggest that there were standing variations that could potentially contribute to adaptation to nonnative environments despite the founder population being small.

RevDate: 2019-07-19
CmpDate: 2019-07-19

White JD, Sarnelle O, SK Hamilton (2017)

Unexpected population response to increasing temperature in the context of a strong species interaction.

Ecological applications : a publication of the Ecological Society of America, 27(5):1657-1665.

Climate change is driving large changes in the spatial and temporal distributions of species, with significant consequences for individual populations. Community- and ecosystem-level implications of altered species distributions may be complex and challenging to anticipate due to the cascading effects of disrupted interactions among species, which may exhibit threshold responses to extreme climatic events. Toxic, bloom-forming cyanobacteria like Microcystis are expected to increase worldwide with climate change, due in part to their high temperature optima for growth. In addition, invasive zebra mussels (Dreissena polymorpha) have caused an increase in Microcystis aeruginosa, a species typically associated with eutrophication, in low-nutrient lakes. We conducted a 13-yr study of a M. aeruginosa population in a low-nutrient lake invaded by zebra mussels. In 10 of the 13 years, there was a significant positive relationship between M. aeruginosa biomass and accumulated degree days, which are projected to increase with climate change. In contrast, Microcystis biomass was up to an order of magnitude lower than predicted by the above relationship during the other three years, including the warmest in the data set, following repeated heat-induced mass mortality of D. polymorpha. Thus, the positive relationship between Microcystis biomass and temperature was negated when its facilitating species was suppressed during a series of exceptionally warm summers. Predicting the net response of a species to climate change may therefore require, at minimum, quantification of responses of both the focal species and species that strongly interact with it over sufficiently long time periods to encompass the full range of climatic variability. Our results could not have been predicted from existing data on the short-term responses of these two interacting species to increased temperature.

RevDate: 2019-07-19
CmpDate: 2019-07-19

Schuster MJ, JS Dukes (2017)

Rainfall variability counteracts N addition by promoting invasive Lonicera maackii and extending phenology in prairie.

Ecological applications : a publication of the Ecological Society of America, 27(5):1555-1563.

Although encroaching woody plants have reduced the global extent of grasslands, continuing increases in soil nitrogen availability could slow this trend by favoring resident herbaceous species. At the same time, projected increases in rainfall variability could promote woody encroachment by aligning spatiotemporal patterns of soil moisture availability with the needs of woody species. We evaluated the responses of two deciduous woody species to these simulated environmental changes by planting seedlings of Quercus palustris and Lonicera maackii into tallgrass prairie communities grown under a factorial combination of increased rainfall variability and nitrogen addition. Lonicera maackii growth was reduced 20% by nitrogen addition, and increased rainfall variability led to 33% larger seedlings, despite greater competition for light and soil resources. In contrast, Q. palustris growth showed little response to either treatment. Increased rainfall variability allowed both species to retain their leaves for an additional 6.5 d in autumn, potentially in response to wetter end-of-season shallow soils. Our findings suggest increases in rainfall variability will counteract the inhibitory effect of nitrogen deposition on growth of L. maackii, extend autumn phenology, and promote the encroachment of some woody species into grasslands.

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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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This is a must read book for anyone with an interest in invasion biology. The full title of the book lays out the author's premise — The New Wild: Why Invasive Species Will Be Nature's Salvation. Not only is species movement not bad for ecosystems, it is the way that ecosystems respond to perturbation — it is the way ecosystems heal. Even if you are one of those who is absolutely convinced that invasive species are actually "a blight, pollution, an epidemic, or a cancer on nature", you should read this book to clarify your own thinking. True scientific understanding never comes from just interacting with those with whom you already agree. R. Robbins

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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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RJR Picks from Around the Web (updated 11 MAY 2018 )