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Canis latrans (Coyote) is a highly mobile, generalist species that occupies a wide variety of habitats and ecoregions across North and Central America. Assessments of population genetic diversity and structure among the recently colonized populations of Coyotes in the eastern US have been conducted at broad spatial scales, revealing genetic structure concordant with immigration routes and high genetic diversity, or at local spatial scales, usually finding genetic panmixia. However, few studies have assessed eastern Coyote genetics at an intermediate spatial scale (i.e., state-level), which may be commensurate with the population dynamics of this mobile animal. We sampled 10 study areas across South Carolina during summer 2019–2020 using noninvasive genetic sampling and 10 microsatellite loci to identify individuals. We assessed genetic diversity and pairwise relatedness as well as genetic structure across our populations to determine whether there were landscape-level differences in genetic differentiation and the scale of Coyote population structure across the state. We found high levels of observed heterozygosity (0.599–0.872) and allelic richness (3.99–5.12) across our sites but low levels of relatedness. We observed low genetic differentiation (pairwise FST = 0.010–0.066) and insignificant isolation by distance with limited evidence of genetic structure. Coyote populations seem to be operating at a spatial extent greater than South Carolina, and gene flow is likely maintained by unrelated, transient individuals. Future research and management of Coyotes in the heterogeneous landscapes of the southeastern US should account for the geographic scale that populations encompass. [ABSTRACT FROM AUTHOR]

The joint influence of abiotic and biotic factors is important for understanding the transmission of generalist pathogens. Abiotic factors such as temperature can directly influence pathogen persistence in the environment and will also affect biotic factors, such as host community composition and abundance. At intermediate spatial scales, the effects of temperature, community composition, and host abundance are expected to contribute to generalist pathogen transmission. We use a simple transmission model to explain and predict how host community composition, host abundance, and environmental pathogen persistence times can independently and jointly influence transmission. Our transmission model clarifies how abiotic and biotic factors can synergistically support the transmission of a pathogen. The empirical data show that high community competence, high abundance, and low temperatures correlate with high levels of transmission of ranavirus in larval amphibian communities. Discrete wetlands inhabited by larval amphibians in the presence of ranavirus provide a compelling case study comprising distinct host communities at a spatial scale anticipated to demonstrate abiotic and biotic influence on transmission. We use these host communities to observe phenomena demonstrated in our theoretical model. These findings emphasize the importance of considering both abiotic and biotic factors, and concomitant direct and indirect mechanisms, in the study of pathogen transmission and should extend to other generalist pathogens with the capacity for environmental transmission. [ABSTRACT FROM AUTHOR]

Mercury (Hg) is a ubiquitous contaminant in wetlands that can cause immunosuppression in birds, which may increase susceptibility to colonization with Salmonella spp. Previously, we found that White Ibis (Eudocimus albus), a recently urbanized wading bird, shed Salmonella spp. at a higher prevalence when captured at urban sites, compared with natural sites. In this study, we sought to determine if Hg burdens in ibis are related to Salmonella status or degree of urbanization or both. We analyzed feathers from 94 ibis in Palm Beach County, Florida, USA, along an urbanization gradient (0-68% urbanization) and from individuals with confirmed Salmonella spp. status (shedding or not shedding). We detected Hg in all ibis feathers (0.22-8.47 mg/kg; mean = 1.96 mg/kg; SD = 1.94). The Hg concentration was not significantly correlated to Salmonella spp. shedding status (Wilcoxon rank sum test, W = 1170; P = 0.596) but was negatively associated with capture site urbanization level (R² = 0.327; P = 0.026). Our findings may suggest that the immunosuppressive effects of Hg do not affect Salmonella shedding in the ibis or that Hg burdens were too low to affect Salmonella shedding status. Further, ibis that were captured in high urbanization sites appeared to have a lower risk of Hg exposure than ibis that were captured within low urbanization sites. [ABSTRACT FROM AUTHOR]

Round whitefish (Prosopium cylindraceum) have abroad, disjunct range across northern North America and Eurasia, and little is known about their genetic population structure. We performed genetic analyses of round whitefish from 17 sites across its range using nine microsatellites, two mitochondrial DNA (mtDNA) loci, and 4918 to 8835 single-nucleotide polymorphism (SNP) loci. Our analyses identified deep phylogenetic division between eastern and western portions of the range, likely indicative of origins from at least two separate Pleistocene glacial refugia. Regionally, microsatellites and SNPs identified congruent patterns in subdivision, and population structure was consistent with expectations based on hydrologic connectivity. Within the Laurentian Great Lakes, Lake Huron and Lake Ontario were identified as key areas of interest. Lake Huron appears to be a contemporary source population for several other Great Lakes, and Lake Ontario contains a genetically discrete group of round whitefish. In all cases, multiple genetic markers yielded similar patterns, but SNPs offered substantially enhanced resolution. We conclude that round whitefish have population subdivision on several scales important for understanding their evolutionary history and conservation planning. Les menominis ronds (Prosopium cylindraceum) ont une vaste aire de repartition discontinue dans le nord de l'Amerique du Nord et l'Eurasie, et les connaissances sur la structure genetique de leurs populations sont tres limitees. Nous avons realise des analyses genetiques de menominis ronds de 17 emplacements a la grandeur de leur aire en utilisant neuf microsatellites, deux sites d'ADN mitochondrial (ADNmt) et de 4918 a 8835 sites de polymorphisme mononucleotidique (SNP). Nos analyses font ressortir une division phylogenetique profonde entre les portions orientale et occidentale de l'aire de repartition, qui indique vraisemblablement des origines remontant a au moins deux refuges glaciaires pleistocenes distincts. A l'echelle regionale, les microsatellites et les SNPs font ressortir des motifs de subdivision congruents, et la structure des populations obtenue concorde avec les previsions basees sur la connectivite hydrologique. Il est etabli que, au sein des Grands Lacs laurentiens, les lacs Huron et Ontario constituent des regions d'interet. La population du lac Huron semble etre une population source contemporaine pour plusieurs autres Grands Lacs, et le lac Ontario renferme un groupe de menominis ronds distinct sur le plan genetique. Dans tous les cas, plusieurs marqueurs genetiques produisent des motifs semblables, mais les SNP offrent une resolution nettement accrue. Nous en concluons que les populations de menominis ronds sont subdivisees a plusieurs echelles importantes pour la comprehension de leur evolution et la planification de leur conservation. [Traduit par la Redaction], Introduction The round whitefish (Salmonidae; Coregoninae; Prosopium cylindraceum) is a widespread species that has become a conservation concern in several regions of North America. In the northeastern United States, several [...]

Coyotes (Canis latrans) colonized the eastern United States over the last century and formed a 3-species predator guild with bobcats (Lynx rufus) and gray foxes (Urocyon cinereoargenteus) across much of the southeastern United States. Diets among the three species vary along with respective impacts on game species such as white-tailed deer (Odocoileus virginianus) and wild turkeys (Meleagris gallopavo). To determine predation impacts on vertebrate prey and dietary overlap in consumption of prey items, we assessed diets of coyote, bobcat, and gray fox during spring, coinciding with white-tailed deer fawning and wild turkey nesting and brood rearing. We sampled across three sites along the Savannah River in South Carolina from mid-May through mid-June of 2020–2021. We collected 180 scat samples along 295.9 kilometers (71.1–122.4 km/site) of unpaved secondary roads and used DNA metabarcoding to determine vertebrate diet items. We identified predator species of scat using DNA metabarcoding and species-specific mtDNA fragment analysis (153 were coyote, 20 bobcat, and seven gray fox). Overall, we found evidence that two species, coyote and bobcat, consumed deer while all three consumed turkeys. Frequency of deer in the diet varied across sites for coyotes from 62–86% and wild turkey was present with a frequency of occurrence of 9% for coyotes, 5% for bobcats, and 14% for gray fox. Vertebrate diet specialization was evident across predator species with high frequency of deer in coyote diets, rabbits and small mammals in bobcat diets, and herpetofauna in gray fox diets. During deer fawning and wild turkey nesting and brood rearing, dietary overlap appears to be mediated by disparate selection of prey items, which reduced competition among coyotes, bobcats, and gray foxes. Use of DNA metabarcoding may augment our understanding of dietary preferences within this predator guild by providing increased resolution of diet composition among important game species. [ABSTRACT FROM AUTHOR]

Exposure to agrochemicals can have lethal and sublethal effects on amphibians. Most toxicology studies only examine exposure during the aquatic larval stage. Survival of the juvenile stage is the most important for population persistence and it is critical to understand the potential impacts of exposure during this life stage. We investigated how short-term exposure to triclopyr, an herbicide commonly used in forestry management, might impact several juvenile traits. To determine if juveniles perceived exposure as an environmental stressor, we measured their release of corticosterone. We also examined dispersal traits by measuring foraging and hopping behavior. We found no evidence that exposure negatively impacted these traits or was a stressor. Our results provide a preliminary assessment of the potential impact of triclopyr on juvenile amphibians, but we recommend additional research on the effects of agrochemicals on juvenile amphibians. [ABSTRACT FROM AUTHOR]

Delineating genetically distinct population segments of threatened species and quantifying population connectivity are important steps in developing effective conservation and management strategies aimed at preventing extinction. The gopher frog (Rana capito) is a xeric-adapted, pond-breeding species endemic to the Gulf and Atlantic coastal plains of the southeastern United States. This species has experienced extensive habitat loss and fragmentation in the formerly widespread longleaf pine-wiregrass savanna where it lives, resulting in individual abundance declines and population extinctions throughout its range. We used individual-based clustering methods along with Bayesian inference of historical migration based on almost 1500 multilocus microsatellite genotypes to examine genetic structure in this taxon. Clustering analyses identified panhandle and peninsular populations in Florida as distinct genetic clusters separated by the Aucilla River, consistent with the division between the Coastal Plain and peninsular mitochondrial lineages, respectively. Analysis of historical migration indicated an east–west population divergence event followed by immigration to the east. Together, our results indicate that the genetically distinct Coastal Plain and peninsular Florida lineages should be considered separately for conservation and management purposes. [ABSTRACT FROM AUTHOR]