Male Dispersal Drives Gene Flow in Timber Rattlesnakes (Crotalus horridus)

Threatened across much of their range, Timber Rattlesnakes (Crotalus horridus) exhibit patterns of genetic diversity that are shaped by movement and aspects of their environment in ways that may foster or constrain conservation. We combine movement data with nuclear and mitochondrial population genetic data to understand the population structure and patterns of gene flow for snakes in four overwintering sites (hibernacula) in central Pennsylvania. Our analyses show that hibernacula separated by only a few kilometers can maintain genetic structure along with high gene flow. Female spatial use rarely overlapped with individuals from adjacent hibernacula, whereas male spatial use typically did overlap with individuals from adjacent hibernacula. This study offers new evidence for how asymmetry in gene flow (with males responsible for inter-hibernaculum matings) shapes Timber Rattlesnake population genetics.