Abstract
Bluemask darters (Etheostoma akatulo) were sampled from the four drainages where extant populations of this narrowly endemic freshwater fish are known to exist. Population genetic diversity and structure were assessed at 10 microsatellite loci. All populations exhibited low levels of genetic variation, with expected heterozygosity ranging from 0.2 to 0.35. Significant population subdivision was found among most tributaries, and genetic divergence was strongly correlated with geographic distance. Bayesian population assignment and pairwise population differentiation measures both identified a lack of differentiation between E. akatulo populations inhabiting Cane Creek and the Caney Fork. This observation reduced the number of distinct breeding populations of this species to three. We also used approximate Bayesian computation to compare three models of demographic history in this species. A constant population size model was favored over models that included historic or recent population reductions. Our results suggest that impoundment of the Caney Fork and its tributaries, by completion of Great Falls Dam in 1916, was not responsible for the reduced genetic diversity in the sampled populations. Given the low levels of genetic diversity within populations and the limited geographic distribution, future conservation efforts should seek to maximize available habitat while simultaneously limiting the influences of anthropogenic stressors in the system.
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Acknowledgments
All collections were made under Tennessee Wildlife Resources Agency permit 750 and U.S. Fish and Wildlife Service Threatened/Endangered permit TE117405-2. Support for this project was provided by the Tennessee Valley Authority and the U.S. Fish and Wildlife Service, Cookeville, Tennessee field office. The authors would like to thank C.L. Phillips, J.T. Baxter, R.A. Kennon, G. Call, T. Shaw, and K. Robinson for assistance with field collections. Additionally, two reviewers provided helpful comments on the manuscript during peer review.
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Robinson, J.D., Simmons, J.W., Williams, A.S. et al. Population structure and genetic diversity in the endangered bluemask darter (Etheostoma akatulo). Conserv Genet 14, 79–92 (2013). https://doi.org/10.1007/s10592-012-0427-x
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DOI: https://doi.org/10.1007/s10592-012-0427-x