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The bertha armyworm (BAW), Mamestra configurata, is a significant pest of canola (Brassica napus L. and B. rapa L.) in western North America that undergoes cyclical outbreaks every 6–8 years. During peak outbreaks millions of dollars are spent on insecticidal control and, even with control efforts, subsequent damage can result in losses worth millions of dollars. Despite the importance of this pest insect, information is lacking on the dispersal ability of BAW and the genetic variation of populations from across its geographic range which may underlie potential differences in their susceptibility to insecticides or pathogens. Here, we examined the genetic diversity of BAW populations during an outbreak across its geographic range in western North America. First, mitochondrial cytochrome oxidase 1 (CO1) barcode sequences were used to confirm species identification of insects captured in a network of pheromone traps across the range, followed by haplotype analyses. We then sequenced the BAW genome and used double-digest restriction site associated DNA sequencing, mapped to the genome, to identify 1000s of single nucleotide polymorphisms (SNP) markers. CO1 haplotype analysis identified 9 haplotypes distributed across 28 sample locations and three laboratory-reared colonies. Analysis of genotypic data from both the CO1 and SNP markers revealed little population structure across BAW’s vast range. The CO1 haplotype pattern showed a star-like phylogeny which is often associated with species whose population abundance and range has recently expanded and combined with pheromone trap data, indicates the outbreak may have originated from a single focal point in central Saskatchewan. The relatively recent introduction of canola and rapid expansion of the canola growing region across western North America, combined with the cyclical outbreaks of BAW caused by precipitous population crashes, has likely selected for a genetically homogenous BAW population adapted to this crop. [ABSTRACT FROM AUTHOR]

Canine circovirus (CanineCV) was detected, together with canine parvovirus (CPV), in samples from an outbreak of fatal gastroenteritis in dogs in Argentina. We obtained the full-length genome of this recently discovered virus by overlapping PCR, designated strain UBA-Baires. Sequence analysis revealed a highly conserved genome but also showed several unique mutations in amino acids from the capsid protein that have not been previously reported. Phylogenetic analysis shows that this strain is more closely related to European strains than to viruses detected in North America or Asia. Although the pathogenic role of CanineCV in dogs is still unclear, this study highlights the importance of CanineCV as a coinfecting virus in disease development. To our knowledge, this is the first report of the involvement of CanineCV in severe clinical disease in dogs in South America. Our results expand our information on the geographical extent of this virus and contribute to the understanding of its role in disease. [ABSTRACT FROM AUTHOR]

In the 1970s, the introduced silver carp Hypophthalmichthys molitrix (which is indigenous to eastern Asia) escaped from southern U.S. aquaculture to spread throughout the Mississippi River basin, and since has steadily moved northward. This large, prolific filter-feeder reduces food availability for other fishes. It now has reached the threshold of the Laurentian Great Lakes, where it likely will significantly impact food chains and fisheries. Our study evaluates population genetic variability and differentiation of the silver carp using 10 nuclear DNA microsatellite loci, and sequences of two mitochondrial genes–cytochrome b and cytochrome c oxidase subunit 1, along with the nuclear ribosomal protein S7 gene intron 1. We analyze population samples from: two primary Great Lakes’ invasion fronts (at the Illinois River outside of Chicago, IL in Lake Michigan and in the Wabash River, which leads into the Maumee River and western Lake Erie), the original establishment “core” in the Lower Mississippi River, and expansion areas in the Upper Mississippi and Missouri rivers. We analyze and compare our results with bighead and other invasive carps, and cyprinid relatives. Results reveal that the silver carp invasion possesses moderate levels of genetic diversity, with more mtDNA haplotypes and unique microsatellite alleles in the “core” Lower Mississippi River population, which also diverges the most. The two invasion fronts also significantly genetically differ. About 3% of individuals (including all populations except the Illinois River) contain a unique and very divergent mtDNA haplotype, which likely stems from historic introgression in Asia with female largescale silver carp H. harmandi. The nuclear microsatellites and S7 sequences of the introgressed individuals do not differ from silver carp and are very distant from bighead carp. These sequence variation data are employed to design and evaluate a targeted high-throughput metabarcoding sequence assay that identifies and distinguishes among species of invasive carps (i.e., silver, bighead, grass, black, and common carps, along with goldfish), as well as native cyprinids, using cytochrome b. Our assay further differentiates among selected silver carp haplotypes (including between H. molitrix and H. harmandi), for use in population genetics and future analyses of spread pathways. We test and evaluate this assay on environmental (e)DNA water samples from 48 bait shops in the Great Lakes’ region (along the Lake Erie, Lake St. Clair, and Wabash River watersheds), using positive and negative controls and custom bioinformatic processing. Test results discern silver carp eDNA in four of the shops–three in Lake Erie and one in the Wabash River watershed–and bighead carp from one of the same Lake Erie venues, suggesting that retailers (who often source from established southerly populations) comprise another introduction vector. Our overall findings thus provide key population genetic and phylogenetic data for understanding and tracing introductions, vectors, and spread pathways for silver carp, their variants, and their relatives. [ABSTRACT FROM AUTHOR]

Accurate species delimitation and description are necessary to guide effective conservation of imperiled species, and this synergy is maximized when multiple data sources are used to delimit species. We illustrate this point by examining Drymarchon couperi (Eastern Indigo Snake), a large, federally-protected species in North America that was recently divided into two species based on gene sequence data from three loci and heuristic morphological assessment. Here, we re-evaluate the two-species hypothesis for D. couperi by evaluating both population genetic and gene sequence data. Our analyses of 14 microsatellite markers revealed 6–8 genetic population clusters with significant admixture, particularly across the contact zone between the two hypothesized species. Phylogenetic analyses of gene sequence data with maximum-likelihood methods suggested discordance between mitochondrial and nuclear markers and provided phylogenetic support for one species rather than two. For these reasons, we place Drymarchon kolpobasileus into synonymy with D. couperi. We suggest inconsistent patterns between mitochondrial and nuclear DNA are driven by high dispersal of males relative to females. We advocate for species delimitation exercises that evaluate admixture and gene flow in addition to phylogenetic analyses, particularly when the latter reveal monophyletic lineages. This is particularly important for taxa, such as squamates, that exhibit strong sex-biased dispersal. Problems associated with over-delimitation of species richness can become particularly acute for threatened and endangered species, because of high costs to conservation when taxonomy demands protection of more individual species than are supported by accumulating data. [ABSTRACT FROM AUTHOR]

Pleistocene glaciations had significant effects on the distribution and evolution of species inhabiting the Holarctic region. Phylogeographic studies concerning the entire region are still rare. Here, we compared global phylogeographic patterns of one boreo-montane and one boreo-temperate butterflies with largely overlapping distribution ranges across the Northern Hemisphere, but with different levels of range fragmentation and food specialization. We reconstructed the global phylogeographic history of the boreo-montane specialist Boloria eunomia (n = 223) and of the boreo-temperate generalist Boloria selene (n = 106) based on mitochondrial and nuclear DNA markers, and with species distribution modelling (SDM). According to the genetic structures obtained, both species show a Siberian origin and considerable split among populations from Nearctic and Palaearctic regions. According to SDMs and molecular data, both butterflies could inhabit vast areas during the moderate glacials. In the case of B. selene, high haplotype diversity and low geographic structure suggest long-lasting interconnected gene flow among populations. A stronger geographic structuring between populations was identified in the specialist B. eunomia, presumably due to the less widespread, heterogeneously distributed food resources, associated with cooler and more humid climatic conditions. Populations of both species show opposite patterns across major parts of North America and in the case of B. eunomia also across Asia. Our data underline the relevance to cover entire distribution ranges to reconstruct the correct phylogeographic history of species. [ABSTRACT FROM AUTHOR]

The coastal tailed frog (Ascaphus truei) is endemic to the Pacific Northwest of North America and is listed as a species of Special Concern under the Canadian Species at Risk Act. Its range is limited to British Columbia where it occurs widely west of the Coast Mountain Ranges extending north almost to the Alaskan Panhandle. The present study focused on surveying within the Cayoosh, Bridge (Shulaps), Seton, Anderson, Carpenter, and Downton Lake drainages. Four years of previous inventory efforts using conventional time-constrained search (TCS) methods detected tailed frog at 23/292 discrete sites (7.9% detection rate) in seven watersheds. Non-invasive environmental DNA (eDNA) methods hold promise for cryptic and low-abundance species detection. We rigorously validated a quantitative real-time polymerase chain reaction (qPCR)-based tool for detecting coastal tailed frog eDNA in water samples. This eASTR4 test is highly specific and sensitive. We applied a two-step targeted eDNA analysis approach on duplicate filtered water samples from a total of 72 sites collected over five days. The first IntegritE-DNA step mitigates false negative results and tests all DNA samples for the ability to support amplification from endogenous plant chloroplast DNA as a measure of sample viability. Three DNA samples failed this step even after inhibitor clean up suggesting that these samples were poor quality and not reliable for targeted species’ DNA analyses. All other DNA samples were deemed viable and were then tested for species-specific DNA. Coastal tailed frog eDNA was detected in 55/72 (76%) discrete stream reaches; nine sites with historical known occurrence were all eDNA positive. The false negative rate for TCS compared to eDNA methods was 58%. The results expand known coastal tailed frog distribution to 24 watersheds effectively more than tripling extant occurrences and confirm a previously suspected, apparently isolated coastal tailed frog metapopulation in the Shulaps drainage. [ABSTRACT FROM AUTHOR]

The salamander family Sirenidae is represented by four extant species that are restricted to North America. Sirens are abundant throughout the southern United States and are among the world’s largest amphibians, yet the biology, ecology, and phylogeography of this group is poorly-known. In this study we use morphological and genetic evidence to describe a previously unrecognized species from southern Alabama and the Florida panhandle. We name this species the Reticulated Siren, Siren reticulata. Future studies will enable more precise phylogenetic information about S. reticulata and will almost surely reveal additional undescribed species within the family. [ABSTRACT FROM AUTHOR]

In the United States (US), the sugarcane aphid (SCA) Melanaphis sacchari (Zehnter) (Hemiptera: Aphididae) was introduced in the 1970s, however at that time it was only considered a pest of sugarcane. In 2013, a massive outbreak of M. sacchari occured on sorghum, resulting in significant economic damage to sorghum grown in North America including the US, Mexico, and Puerto Rico. The aim of the present study was to determine if the SCA pest emergence in American sorghum resulted from the introduction of new genotypes. To this end we used microsatellite markers and COI sequencing to compare the genetic diversity of SCA populations collected in the Americas after the 2013 SCA outbreak on sorghum (during 2013–2017) to older samples collected before the pest outbreak (during 2007–2009). Our results show that the SCA outbreak in the Americas and the Caribbean observed since 2013 belong to populations exhibiting low genetic diversity and consisting of a dominant clonal lineage, MLL-F, which colonizes Sorghum spp. and sugarcane. The comparison of MLL-F specimens collected post-2013 with specimens collected in Louisiana in 2007 revealed that both populations are genetically distinct, according to COI sequencing and microsatellite data analyses. Our result suggest that MLL-F is a new invasive genotype introduced into the Americas that has spread rapidly across sorghum growing regions in the US, Mexico, Honduras and the Caribbean. The origin of this introduction is either Africa or Asia, with Asia being the most probable source. [ABSTRACT FROM AUTHOR]

Horses were a dominant component of North American Pleistocene land mammal communities and their remains are well represented in the fossil record. Despite the abundant material available for study, there is still considerable disagreement over the number of species of Equus that inhabited the different regions of the continent and on their taxonomic nomenclature. In this study, we investigated cheek tooth morphology and ancient mtDNA of late Pleistocene Equus specimens from the Western Interior of North America, with the objective of clarifying the species that lived in this region prior to the end-Pleistocene extinction. Based on the morphological and molecular data analyzed, a caballine (Equus ferus) and a non-caballine (E. conversidens) species were identified from different localities across most of the Western Interior. A second non-caballine species (E. cedralensis) was recognized from southern localities based exclusively on the morphological analyses of the cheek teeth. Notably the separation into caballine and non-caballine species was observed in the Bayesian phylogenetic analysis of ancient mtDNA as well as in the geometric morphometric analyses of the upper and lower premolars. Teeth morphologically identified as E. conversidens that yielded ancient mtDNA fall within the New World stilt-legged clade recognized in previous studies and this is the name we apply to this group. Geographic variation in morphology in the caballine species is indicated by statistically different occlusal enamel patterns in the specimens from Bluefish Caves, Yukon Territory, relative to the specimens from the other geographic regions. Whether this represents ecomorphological variation and/or a certain degree of geographic and genetic isolation of these Arctic populations requires further study. [ABSTRACT FROM AUTHOR]

Cornus florida (flowering dogwood) and C. nuttallii (Pacific dogwood) are North American native tree species that belong to the big-bracted group of dogwoods. Cornus species are highly valued for their ornamental characteristics, and have fruits that contain high fat content for animals. Also, they are an important understory tree in natural forests. Dogwood anthracnose, caused by Discula destructiva, was observed in the late 1970s on the east and west coasts of the United States and by 1991 had quickly spread throughout most of the native ranges of C. florida and C. nuttalli. We investigated the genetic diversity and population structure of 93 D. destructiva isolates using 47 microsatellite loci developed from the sequenced genome of the type strain of D. destructiva. Clone-corrected data indicated low genetic diversity and the presence of four genetic clusters that corresponded to two major geographic areas, the eastern United States and the Pacific Northwest, and to the two collection time periods when the isolates were collected (pre- and post-1993). Linkage disequilibrium was present in five out of six subpopulations, suggesting that the fungus only reproduced asexually. Evidence of population bottlenecks was indicated across four identified genetic clusters, and was probably the result of the limited number of founding individuals on both coasts. These results support the hypothesis that D. destructiva is an exotic pathogen with independent introductions on the east and west coasts of North America. We also tested the cross-amplification of these microsatellite primers to other Discula species. Genomic DNA from 17 isolates of four other Discula species and two isolates of Juglanconis species (formerly Melanconis species) were amplified by 17 of 47 primer pairs. These primers may be useful for investigating the genetic diversity and population structure of these Discula species. [ABSTRACT FROM AUTHOR]

Shrews of the Sorex genus are an evolutionarily successful group that includes more than 77 species widely distributed in Eurasia and North America. The genus is one of the rare cases where karyotypic changes reflect well the evolutionary relationships among its species. The taxa showing the greatest variation in karyotype are usually classified into the Sorex araneus group. Its evolution was associated with chromosomal rearrangements, which could have promoted fast diversification of this group into many chromosomal races and species. These processes were additionally complicated by introgressions of mitochondrial DNA, which made the evolutionary history of this group quite complex and difficult to infer. To tackle the problem, we performed multi-method phylogenetic analyses based on mitochondrial cytochrome b that is considered a good molecular marker available for many representatives of Sorex. The results were compared with phylogenies based on chromosomal rearrangement data and put into temporal and spatial context using molecular dating and historical biogeography methods. We complemented the study with the estimation of diversification rates within the S. araneus group as well as comparing the results with paleontological records and climatic oscillations within the last 4 million years. Based on the gathered data, we proposed a hypothetical scenario for the evolution and geographic dispersion of species belonging to the S. araneus group. The shrews began to diversify about 2.7 million years ago in Eurasia and then migrated at least twice to North America. The evolution of shrews was driven by Pleistocene glacial and interglacial cycles, which increased their speciation rate and the emergence of new lineages. The migrations of populations were accompanied by introgressions of mitochondrial DNA into native shrews and occurred at least twice. [ABSTRACT FROM AUTHOR]

The extent to which evolution is deterministic (predictable), or random, is a fundamental question in evolution. This case study attempts to determine the extent to which interspecific divergence can be predicted from intraspecific trends related species. The mountainous Lesser Antilles are occupied by one or two anole species with very substantial intraspecific differences in the quantitative traits between xeric and rainforest habitats. These ecologically determined differences tend to be in parallel in each island species. A related species (Anolis bonairensis) lives on the far more xeric island of Bonaire, and this study tests the extent to which its interspecific divergence in hue and pattern traits can be predicted from the parallel intraspecific variation exhibited in Lesser Antillean anoles. Regression against a multivariate climate variable suggests that the hue and pattern of the Bonaire anole are consistently predicted from the ecologically determined intraspecific variation of its Lesser Antillean relatives. However, this predictability may be less consistent with other character systems, for example, scalation. [ABSTRACT FROM AUTHOR]

Here we conduct research to understand the evolutionary history of a shrubby species known as Agarito (Berberis trifoliolata), an endemic species to the Chihuahuan Desert. We identify genetic signatures based on plastid DNA and AFLP markers and perform niche modelling and spatial connectivity analyses as well as niche modelling based on records in packrats to elucidate whether orogenic events such as mountain range uplift in the Miocene or the contraction/expansion dynamics of vegetation in response to climate oscillations in the Pliocene/Pleistocene had an effect on evolutionary processes in Agarito. Our results of current niche modelling and palaeomodelling showed that the area currently occupied by Berberis trifoliolata is substantially larger than it was during the Last Interglacial period and the Last Glacial Maximum. Agarito was probably confined to small areas in the Northeastern and gradually expanded its distribution just after the Last Glacial Maximum when the weather in the Chihuahuan Desert and adjacent regions became progressively warmer and drier. The most contracted range was predicted for the Interglacial period. Populations remained in stable areas during the Last Glacial Maximum and expanded at the beginning of the Holocene. Most genetic variation occured in populations from the Sierra Madre Oriental. Two groups of haplotypes were identified: the Mexican Plateau populations and certain Northeastern populations. Haplogroups were spatially connected during the Last Glacial Maximum and separated during interglacial periods. The most important prediction of packrat middens palaeomodelling lies in the Mexican Plateau, a finding congruent with current and past niche modelling predictions for agarito and genetic results. Our results corroborate that these climate changes in the Pliocene/Pleistocene affected the evolutionary history of agarito. The journey of agarito in the Chihuahuan Desert has been dynamic, expanding and contracting its distribution range and currently occupying the largest area in its history. [ABSTRACT FROM AUTHOR]

Blastomyces dermatitidis and Blastomyces gilchristii are dimorphic fungal pathogens that cause serious pulmonary and systemic infections in humans. Although their natural habitat is in the environment, little is known about their specific ecologic niche(s). Here, we analyzed 25 microsatellite loci from 169 strains collected from various regions throughout their known endemic range in North America, representing the largest and most geographically diverse collection of isolates studied to date. Genetic analysis of multilocus microsatellite data divided the strains into four populations of B. dermatitidis and four populations of B. gilchristii. B. dermatitidis isolates were recovered from areas throughout North America, while the B. gilchristii strains were restricted to Canada and some northern US states. Furthermore, the populations of both species were associated with major freshwater drainage basins. The four B. dermatitidis populations were partitioned among (1) the Nelson River drainage basin, (2) the St. Lawrence River and northeast Atlantic Ocean Seaboard drainage basins, (3) the Mississippi River System drainage basin, and (4) the Gulf of Mexico Seaboard and southeast Atlantic Ocean Seaboard drainage basins. A similar partitioning of the B. gilchristii populations was observed among the more northerly drainage basins only. These associations suggest that the ecologic niche where the sexual reproduction, growth, and dispersal of B. dermatitidis and B. gilchristii occur is intimately linked to freshwater systems. For most populations, sexual reproduction was rare enough to produce significant linkage disequilibrium among loci but frequent enough that mating-type idiomorphic ratios were not skewed from 1:1. Furthermore, the evolutionary divergence of B. dermatitidis and B. gilchristii was estimated at 1.9 MYA during the Pleistocene epoch. We suggest that repeated glaciations during the Pleistocene period and resulting biotic refugia may have provided the impetus for speciation as theorized for other species associated with temperate freshwater systems. [ABSTRACT FROM AUTHOR]

Wild birds, including waterfowl such as ducks, are reservoir hosts of influenza A viruses. Despite the increased number of avian influenza virus (AIV) genome sequences available, our understanding of AIV genetic structure and transmission through space and time in waterfowl in North America is still limited. In particular, AIVs in ducks of the Atlantic flyway of North America have not been thoroughly investigated. To begin to address this gap, we analyzed 109 AIV genome sequences from ducks in the Atlantic flyway to determine their genetic structure and to document the extent of gene flow in the context of sequences from other locations and other avian and mammalian host groups. The analyses included 25 AIVs from ducks from Newfoundland, Canada, from 2008–2011 and 84 available reference duck AIVs from the Atlantic flyway from 2006–2011. A vast diversity of viral genes and genomes was identified in the 109 viruses. The genetic structure differed amongst the 8 viral segments with predominant single lineages found for the PB2, PB1 and M segments, increased diversity found for the PA, NP and NS segments (2, 3 and 3 lineages, respectively), and the highest diversity found for the HA and NA segments (12 and 9 lineages, respectively). Identification of inter-hemispheric transmissions was rare with only 2% of the genes of Eurasian origin. Virus transmission between ducks and other bird groups was investigated, with 57.3% of the genes having highly similar (≥99% nucleotide identity) genes detected in birds other than ducks. Transmission between North American flyways has been frequent and 75.8% of the genes were highly similar to genes found in other North American flyways. However, the duck AIV genes did display spatial distribution bias, which was demonstrated by the different population sizes of specific viral genes in one or two neighbouring flyways compared to more distant flyways. [ABSTRACT FROM AUTHOR]

To gain a better understanding of North American population history, complete mitochondrial genomes (mitogenomes) were generated from four ancient and three living individuals of the northern Northwest Coast of North America, specifically the north coast of British Columbia, Canada, current home to the indigenous Tsimshian, Haida, and Nisga’a. The mitogenomes of all individuals were previously unknown and assigned to new sub-haplogroup designations D4h3a7, A2ag and A2ah. The analysis of mitogenomes allows for more detailed analyses of presumed ancestor–descendant relationships than sequencing only the HVSI region of the mitochondrial genome, a more traditional approach in local population studies. The results of this study provide contrasting examples of the evolution of Native American mitogenomes. Those belonging to sub-haplogroups A2ag and A2ah exhibit temporal continuity in this region for 5000 years up until the present day. Of possible associative significance is that archaeologically identified house structures in this region maintain similar characteristics for this same period of time, demonstrating cultural continuity in residence patterns. The individual dated to 6000 years before present (BP) exhibited a mitogenome belonging to sub-haplogroup D4h3a. This sub-haplogroup was earlier identified in the same general area at 10300 years BP on Prince of Wales Island, Alaska, and may have gone extinct, as it has not been observed in any living individuals of the Northwest Coast. The presented case studies demonstrate the different evolutionary paths of mitogenomes over time on the Northwest Coast. [ABSTRACT FROM AUTHOR]

GRB-associated binding protein 2 (GAB2) represents a compelling genome-wide association signal for late-onset Alzheimer’s disease (LOAD) with reported odds ratios (ORs) ranging from 0.75–0.85. We tested eight GAB2 variants in four North American Caucasian case-control series (2,316 LOAD, 2,538 controls) for association with LOAD. Meta-analyses revealed ORs ranging from (0.61–1.20) with no significant association (all p>0.32). Four variants were hetergeneous across the populations (all p<0.02) due to a potentially inflated effect size (OR = 0.61–0.66) only observed in the smallest series (702 LOAD, 209 controls). Despite the lack of association in our series, the previously reported protective association for GAB2 remained after meta-analyses of our data with all available previously published series (11,952-22,253 samples; OR = 0.82–0.88; all p<0.04). Using a freely available database of lymphoblastoid cell lines we found that protective GAB2 variants were associated with increased GAB2 expression (p = 9.5×10−7−9.3×10−6). We next measured GAB2 mRNA levels in 249 brains and found that decreased neurofibrillary tangle (r = −0.34, p = 0.0006) and senile plaque counts (r = −0.32, p = 0.001) were both good predictors of increased GAB2 mRNA levels albeit that sex (r = −0.28, p = 0.005) may have been a contributing factor. In summary, we hypothesise that GAB2 variants that are protective against LOAD in some populations may act functionally to increase GAB2 mRNA levels (in lymphoblastoid cells) and that increased GAB2 mRNA levels are associated with significantly decreased LOAD pathology. These findings support the hypothesis that Gab2 may protect neurons against LOAD but due to significant population heterogeneity, it is still unclear whether this protection is detectable at the genetic level. [ABSTRACT FROM AUTHOR]

An integral part to understanding the biology of an invasive species is determining its origin, particularly in pest species. As one of the oldest known invasive species, the goals of this study were to evaluate the evidence of a westward expansion of Hessian fly into North America, from a potential singular introduction event, and the population genetic structure of current populations. Levels of genetic diversity and population structure in the Hessian fly were compared across North America, Europe, North Africa, Western Asia, and New Zealand. Furthermore, Old World populations were evaluated as possible sources of introduction. We tested diversity and population structure by examining 18 microsatellite loci with coverage across all four Hessian fly chromosomes. Neither genetic diversity nor population genetic structure provided evidence of a westward movement from a single introduction in North America. Introduced populations in North America did not show identity or assignment to any Old World population, likely indicating a multiple introduction scenario with subsequent gene flow between populations. Diversity and selection were assessed on a chromosomal level, with no differences in diversity or selection between chromosomes or between native and introduced populations. [ABSTRACT FROM AUTHOR]

The pinewood nematode, Bursaphelenchus xylophilus, native to North America, is the causative agent of pine wilt disease and among the most important invasive forest pests in the East-Asian countries, such as Japan and China. Since 1999, it has been found in Europe in the Iberian Peninsula, where it also causes significant damage. In a previous study, 94 pairs of microsatellite primers have been identified in silico in the pinewood nematode genome. In the present study, specific PCR amplifications and polymorphism tests to validate these loci were performed and 17 microsatellite loci that were suitable for routine analysis of B. xylophilus genetic diversity were selected. The polymorphism of these markers was evaluated on nematodes from four field origins and one laboratory collection strain, all originate from the native area. The number of alleles and the expected heterozygosity varied between 2 and 11 and between 0.039 and 0.777, respectively. First insights into the population genetic structure of B. xylophilus were obtained using clustering and multivariate methods on the genotypes obtained from the field samples. The results showed that the pinewood nematode genetic diversity is spatially structured at the scale of the pine tree and probably at larger scales. The role of dispersal by the insect vector versus human activities in shaping this structure is discussed. [ABSTRACT FROM AUTHOR]

Cooperative breeding is generally associated with increased philopatry and sedentariness, presumably because short-distance dispersal facilitates the maintenance of kin groups. There are, however, few data on long-distance dispersal in cooperative breeders—the variable likely to be important for genetic diversification and speciation. We tested the hypothesis that cooperative breeders are less likely to engage in long-distance dispersal events by comparing records of vagrants outside their normal geographic range for matched pairs (cooperatively vs. non-cooperatively breeding) of North American species of birds. Results failed to support the hypothesis of reduced long-distance dispersal among cooperative breeders. Thus, our results counter the conclusion that the lower rate of speciation among cooperative breeding taxa found in recent analyses is a consequence of reduced vagility. [ABSTRACT FROM AUTHOR]