Microgeographic genetic structure in the yellow-pine chipmunk (Tamias amoenus)

While there is evidence for broad-scale genetic structure in small mammals, few studies have used variable DNA-based genetic markers to examine geneti c differentiation at microgeographic (tens of kilometres) scales. Yellow-pi ne chipmunks (Tamias amoenus) live in the heterogeneous landscape of the Ro ckies in southwest Alberta and are generally restricted to areas of low ele vation. We used seven microsatellite loci to determine whether chipmunks sh ow evidence of population genetic structure among three closely situated si tes (< 15 km) in the Kananaskis Valley, Alberta. We found evidence for gene tic structure in the form of significant differences in allele frequencies among populations and significantly nonzero values of F-ST for both overall and pairwise population comparisons. However, F-IS values for each populat ion were not significantly different from zero, suggesting little evidence for inbreeding within populations. Genetic differentiation probably occurs as a result of the strong effect of drift in very small (N-e <approximate t o> 25) populations of these animals even in the face of substantial immigra tion rates.