The snails the dinosaurs saw: are the pleurocerid populations of the Older Appalachians a relict of the Paleozoic Era?

Abstract

AbstractPleurocerid snails are a common element of the benthos in rivers and streams throughout the Appalachian highlands from Virginia to Georgia on both sides of the continental divide. Yet their dispersal capabilities are so limited today that significant gene frequency differences have been demonstrated over a scale of meters. We obtained mitochondrial cytochrome oxidase c subunit I (COI) sequence data from 3 individual snails sampled from each of 13 populations of pleurocerids representing 3 species—Leptoxis carinata (4 populations), Goniobasis (“Elimia”) catenaria (4 populations), and Goniobasis (“Elimia”) proxima (5 populations). To these data we added previously published COI sequences from 3 other G. proxima populations. Levels of intrapopulation sequence divergence were strikingly high, ranging up to 21.9% within populations and 22.6% between populations within species. A neighbor-joining analysis revealed 3 loose clusters corresponding to the species, but featured numerous extreme outliers. Wil...