Genetic Analysis of Beaver Reintroductions in Texas

The restoration of Castor canadensis in Texas is one of the state’s greatest conservation success stories. By 1900, overexploitation by fur trappers decimated beaver numbers in the state and the species was thought to be extirpated from east Texas. Between 1939 and 1942, 129 beavers were translocated from source populations along the South Llano River of Edwards and Kimble Counties in southwest Texas were relocated into 27 eastern counties in an effort to restore the species. How this extirpation and subsequent reintroductions has impacted the genetic composition of present-day beaver populations is currently not known. Given the local extirpation in east Texas prior to 1900, our working hypothesis for this study was that current east Texas populations are wholly connected genetically to populations from southwest Texas. To address this question, we used mitochondrial DNA and microsatellite markers to determine the genetic effect of this bottleneck and connect present day populations to relict populations. To make this determination, we obtained samples from wildlife services, live trapping, incidental finds, and museum specimens from various regions across the state. Using mitochondrial markers, haplotype network analyses were used to reconstruct gene-flow patterns and historical events in current Texas populations. This reconstruction supports the hypothesis that significant gene flow has occurred across Texas beaver populations and that there is a genetic signature of past reintroduction events detectable. This indicates that while past conservation actions may have had some effect on repopulation, subsequent recolonization was a major factor in population recovery of Castor Canadensis.