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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]