Pliocene origins, Pleistocene refugia, and postglacial range expansions in southern devil scorpions (Vaejovidae: Vaejovis carolinianus )

The Southern Appalachians and adjacent provinces of the southeastern USA are geologically and biologically diverse, with high levels of endemism. Phylogeographic analyses indicate that animals with small distributions in these regions often contain cryptic diversity and that Pleistocene climate fluctuations had significant impacts on their distributions. We studied the phylogeography of Vaejovis carolinianus (Beauvois), a common forest scorpion from the region, to determine if a more widely distributed animal exhibits similar patterns. Mitochondrial and nuclear DNA, as well as species distribution models, were used to test biogeographic hypotheses. Results indicate that the species is composed of at least nine geographically structured mitochondrial clades. Seven clades are represented by only a few sampling locations, whereas two clades are much larger and appear to be the result of postglacial range expansion in the plateaus and coastal plains adjacent to the Southern Appalachians. A highly disjunct population from Tunica Hills of Louisiana appears to have been isolated since the Pliocene, rejecting a hypothesis of late glacial migration along the Blufflands escarpment. Nuclear DNA is much less structured, perhaps due to differences in habitat and dispersal capabilities between sexes. Although mitochondrial lineages are quite old, mito-nuclear discordance suggests that lineages have not sorted and that V. carolinianus should be treated as a single genetically diverse species.