Date of Graduation

5-2013

Document Type

Thesis

Degree Name

Master of Science in Biology (MS)

Degree Level

Graduate

Department

Biological Sciences

Advisor/Mentor

Marlis R. Douglas

Committee Member

Michael E. Douglas

Second Committee Member

Steven J. Beaupre

Keywords

Biological sciences, Agkistrodon, Central-peripheral hypothesis, Genetic structure, Hibernacula, Microsatellite, Multiple paternity

Abstract

The focus of molecular studies in North American pitvipers has been on species that warrant conservation concern, such as Timber (Crotalus horridus) and Massasauga rattlesnakes (Sistrurus catenatus). Scant effort has been directed towards the molecular ecology of the Copperhead (Agkistrodon contortrix), other than to evaluate male reproduction in a laboratory setting and phylogenetic history. Thus, employing DNA-based molecular techniques to study the natural history of A. contortrix will broaden our knowledge of molecular ecology in North American pitvipers, and particularly in a non-threatened species that can serve as a surrogate for threatened and endangered taxa. Our study will also provide insight into the population genetics of a peripheral population to supplement previous studies regarding the Central-Peripheral Hypothesis and the importance of adaptive genetic variation in peripheral populations as a hedge for environmental change. We employed 23 polymorphic tetra-nucleotide microsatellite loci to explore population parameters in A. c. mokasen at its most northern distribution. Six admixed genetic clusters were identified across 9 dens with intra-den relatedness not significantly different from the population average. Mean male and female relatedness did not differ either within hibernacula or in the adult population. Molecular effective population size is 93.6 individuals (CI = 78.7-113.5) whereas adult census size from mark-recapture is 116 individuals. Molecular evidence for a recent genetic bottleneck was noted in the study population. Several litters with known mothers were assigned to more than one male, indicating multiple paternity, with significant paternal skew detected in one litter. Our study detailed population genetic parameters of a non-threatened pitviper that may be useful in comparative studies with threatened and endangered pitvipers, and is the first to document multiple paternity and paternal skew in a free-living population of Copperhead snakes.

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