Mitochondrial DNA Variation in the Ouachita Map Turtle

We examined mitochondrial DNA sequence variation among populations of the Ouachita Map turtle (Graptemys ouachitensis ouachitensis), an aquatic species distributed throughout the Mississippi River drainage. We sequenced a 620 base-pair segment of the mitochondrial control region for 65 individuals collected throughout this turtle's range, identifying 18 haplotypes that form two minimally divergent groups. These haplotype groups exhibit substantial range overlap. A presumably disjunct population from the Scioto River in Ohio is represented by both haplotypes groups. The limited genetic differentiation observed suggests that the broad geographic range of haplotypes of G. o. ouachitensis reflects considerable dispersal from two Pleistocene glacial refugia, possibly Mississippi River and Teays River.