Population genetics of the eastern box turtle, Terrapene c. carolina

Genetic analyses have become indispensable in species conservation. They are increasingly widespread, accessible and inexpensive. In this dissertation I capitalize on these developments to investigate the population genetics of the eastern box turtle, Terrapene c. carolina. Its demographic decline has been well documented but few studies have evaluated the genetic ramifications of this, and none across the subspecies range. I address here three issues central to the conservation of the eastern box turtle. In my first chapter I evaluate the relatedness of individuals at small geographic scales. I found that at four sites across the range, most individuals were unrelated, with only 10% of pairs being first- or second-degree relatives. Computationally reconstructed parental genotypes for 67 subadults suggested that promiscuity is high in box turtles. Though it is thought that dispersal is low in this species, full siblings were found an average of 11.6 km apart. Finally, I failed to detect any population structure at the fine geographic scale. In my second chapter I scaled my population analyses up to most of the species range. I found evidence for only two populations across the range, though this may be a historical signal. The boundary between them followed the Appalachian Mountains, though population delineation may be more likely caused by isolation by distance. In my third chapter I explore the hypothesis that in the highly fragmented Midwest, contemporary gene flow could be operating along riparian corridor habitat, which is often the only remaining hardwood forest in these areas. I found that isolation by distance was significantly higher along direct lines among sample sites than along least cost paths that generally followed riparian corridors. Collectively, these data provide several novel and counterintuitive insights into box turtle biology, which have implications for the conservation of other forest-dwelling taxa and should provide a foundation for further research