Conservation genetic assessment of the paleback darter (Etheostoma pallididorsum), a narrowly distributed endemic in the Ouachita Highlands, Arkansas, USA

The Paleback Darter is considered imperiled and has recently been petitioned for listing under the Endangered Species Act. Prior allozyme-based studies found evidence of small effective population size, warranting conservation concern. The objective of this study was to assess population dynamics and the phylogeographic history of the Paleback Darter, using a multilocus microsatellite approach and mitochondrial DNA. The predictions of this study were that Paleback Darter populations will exhibit low genetic diversity and minimal gene flow; population structure will correspond to river systems where samples are derived; the reservoir dams impounding the reaches between the Caddo and Ouachita rivers would serve as effective barriers to gene flow; and the Caddo and Ouachita rivers are reciprocally monophyletic. Microsatellite DNA loci revealed significant structure among sampled localities (global Fst = 0.17, P < 0.001), with evidence of two distinct populations representing the ...