Genetic structure and diversity of variegate darters (Etheostoma variatum) in the Big Sandy River drainage

Variegate darters (Etheostoma variatum) are widespread throughout the upper Ohio River drainage, but the effects of landscape features on the population genetic structure of this species are unstudied.  We used microsatellite DNA markers to conduct a preliminary investigation of the population structure and genetic diversity of variegate darters in the Big Sandy River drainage.  Both STRUCTURE and F_ST analyses indicated the existence of three populations: Tug Fork watershed, Levisa Fork watershed upstream of Fishtrap Lake, and Levisa Fork watershed downstream of Fishtrap Lake. Levels of genetic diversity within all three populations were consistent with large contemporary effective population sizes, and no population exhibited evidence of a recent bottleneck. Pairwise F_ST values indicated greater genetic differentiation between Tug and Levisa Fork populations than between populations upstream and downstream of the reservoir within the Levisa Fork. These results will in incorporated into future analysis of variegate darter genetic structure and diversity across the rest of its range.