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Levine B.A.,University of Arkansas | Levine B.A.,Copperhead Institute | Smith C.F.,Wofford College | Smith C.F.,Copperhead Institute | And 7 more authors.
Copeia | Year: 2016

Population genetic data are an important standard with which to gauge demography and gene flow within and among biodiversity units, and are often gathered on species of conservation concern. Yet an exclusive focus on 'conservation immediacy' can also have negative consequences. For example, it can shift monitoring efforts away from more abundant and/or widely distributed clades and, by so doing, promote a more myopic approach to conservation and management. A current example concerns North American pitvipers (Viperidae: Crotalinae), within which listed species of Crotalus and Sistrurus receive considerable population genetic attention whereas broadly distributed Agkistrodon is largely overlooked. To address this disparity, we used 22 polymorphic tetra-nucleotide microsatellite loci to explore genetic structure, diversity, and relatedness in a Connecticut population of Copperhead (A. contortrix). Three admixed genetic clusters were identified across five winter dens, with overall and sex-specific relatedness similar among dens and across the population. First- and second-order relationships were identified within the population, then juxtaposed against known den associations. Values for genetic structure, diversity, and effective population size are similar to those reported for populations of North American Crotalus and Sistrurus. However, the study population did not sustain a genetic bottleneck following recent anthropogenic habitat alterations, and this may reflect a potential resilience to environmental change, particularly when compared with North American Crotalus and Sistrurus. Our results underscore the importance of (1) quantifying population-level parameters in non-threatened crotalines so as to broaden and extend our understanding of anthropogenic impacts, and (2) evaluating population genetics in taxa that appear superficially resilient to anthropogenic modifications. The latter may also promote valuable comparative analyses with threatened and endangered taxa. © 2016 by the American Society of Ichthyologists and Herpetologists. Source


Smith C.F.,Copperhead Institute | Smith C.F.,Wofford College | Schuett G.W.,Copperhead Institute | Schuett G.W.,Georgia State University
Northeastern Naturalist | Year: 2015

Pair-bonding between sexes is common in vertebrate taxa, yet it has been noted far less frequently in some groups such as reptiles, and snakes in particular. Evidence to date indicates that many snake mating-systems are polyandrous, with both males and females having multiple partners in a single breeding season, and thus unlikely to exhibit lengthy pair-bonds. Wittenberger and Tilson (1980) suggested that pair-bonding exists when pairs remain intact for a consecutive period equaling at least 25% of the breeding season. Using this criterion, we present evidence of pair-bond formation in a North American pitviper, Agkistrodon contortrix (Copperhead), a species with a polyandrous mating system. © 2015, Humboldt Field Research Institute. All rights reserved. Source


Booth W.,North Carolina State University | Booth W.,University of Tulsa | Smith C.F.,Wofford College | Smith C.F.,Copperhead Institute | And 6 more authors.
Biology Letters | Year: 2012

Facultative parthenogenesis (FP)-asexual reproduction by bisexual species-has been documented in a variety of multi-cellular organisms but only recently in snakes, varanid lizards, birds and sharks. Unlike the approximately 80 taxa of unisexual reptiles, amphibians and fishes that exist in nature, FP has yet to be documented in the wild. Based on captive documentation, it appears that FP is widespread in squamate reptiles (snakes, lizards and amphisbaenians), and its occurrence in nature seems inevitable, yet the task of detecting FPinwild individuals has been deemed formidable. Herewe show, usingmicrosatelliteDNAgenotyping and litter characteristics, the first cases of FP in wild-collected pregnant females and their offspring of two closely related species of North American pitviper snakes-the copperhead (Agkistrodon contortrix) and cottonmouth (Agkistrodon piscivorus). Our findings support the view that non-hybrid origins of parthenogenesis, such as FP, are more common in squamates than previously thought. With this confirmation, FP can no longer be viewed as a rare curiosity outside the mainstream of vertebrate evolution. Future research on FP in squamate reptiles related to proximate control of induction, reproductive competence of parthenogens and population genetics modelling is warranted. © 2012 The Royal Society. Source


Clark R.W.,San Diego State University | Schuett G.W.,Georgia State University | Schuett G.W.,Copperhead Institute | Repp R.A.,National Optical Astronomy Observatory | And 4 more authors.
PLoS ONE | Year: 2014

Long-term studies of individual animals in nature contribute disproportionately to our understanding of the principles of ecology and evolution. Such field studies can benefit greatly from integrating the methods of molecular genetics with traditional approaches. Even though molecular genetic tools are particularly valuable for species that are difficult to observe directly, they have not been widely adopted. Here, we used molecular genetic techniques in a 10-year radio-telemetric investigation of the western diamond-backed rattlesnake (Crotalus atrox) for an analysis of its mating system and to measure sexual selection. Specifically, we used microsatellite markers to genotype 299 individuals, including neonates from litters of focal females to ascertain parentage using full-pedigree likelihood methods. We detected high levels of multiple paternity within litters, yet found little concordance between paternity and observations of courtship and mating behavior. Larger males did not father significantly more offspring, but we found evidence for size-specific male-mating strategies, with larger males guarding females for longer periods in the mating seasons. Moreover, the spatial proximity of males to mothers was significantly associated with reproductive success. Overall, our field observations alone would have been insufficient to quantitatively measure the mating system of this population of C. atrox, and we thus urge more widespread adoption of molecular tools by field researchers studying the mating systems and sexual selection of snakes and other secretive taxa. © 2014 Clark et al. Source

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