Conservation genetic studies of the endangered Cape Fear Shiner, Notropis mekistocholas (Teleostei: Cyprinidae)

Genetic variation at ten microsatellite loci and one anonymous-nuclear locus was assayed for three geographic samples of the critically endangered North American cyprinid Notropis mekistocholas (Cape Fear shiner). Despite low abundance of this species, there was little suggestion of small population effects; allele diversity and hetero- zygosity were relatively high, FIS values within samples were non-significant, and genotypes were distributed in frequencies according to Hardy-Weinberg expectations. Genetic divergence among samples was minimal despite the presence of dams, constructed in the early 1900s, that separate the sample sites. This suggests that recent gene flow has been sufficient to inhibit genetic divergence or that gene flow has been reduced but there has been insufficient time for genetic divergence to develop. Tests of heterozygosity excess were non-significant, suggesting that N. mekistocholas in the localities sampled have not undergone recent reductions in effective population size. Future studies employing larger sample sizes to provide more robust tests of population structure and temporally separated samples to estimate contemporaneous Nare warranted.