Genetic structuring of relict populations of Gapper's red-backed vole (Clethrionomys gapperi)

We evaluated genetic variation in Gapper's red-backed vole (Clethrionomys g apperi) at 2 microsatellite DNA loci and related our results to the biogeog raphic history of the southern Appalachians. To investigate population gene tic structuring within relictual habitats, 222 individuals were sampled fro m 9 sites, including 2 populations suspected to have been isolated since th e Wisconsin glacial retreat. Genetic structuring was evident among the majo rity of the sampled populations. Unbiased estimates of exact P-values revea led significant allelic differentiation between 15 of 36 population pairs. Overall estimates of F-ST and rho were 0.07 and 0.10, respectively, indicat ing moderate genetic subdivision. Overall gene flow was estimated indirectl y with 3 methods and was 1.13-4.44 migrants/generation. The hypothesized is olation of 2 islandlike populations at Massanutten and Peaks of Otter was s upported by our data and was most apparent in the Massanutten population, w here genetic diversity was low compared with all other populations. The uni que genetic structure of the population at Massanutten also may be related to habitat disturbances. Genetic patterns observed in relict populations of the red-backed vole may provide insight into genetic structuring of codist ributed boreal populations in the southern Appalachians.