Historical biogeography of Farancia abacura (Colubridae): Effect of Pleistocene glaciations as inferred from analysis of mitochondrial DNA

The biogeography of mud snakes (Farancia abacura ) was examined using mitochondrial DNA analysis. Five specimens were chosen, representing eastern and western F. abacura as well as one individual from the zone of intergradation. The complete cytochrome b gene of each individual was amplified via the polymerase chain reaction and was sequenced with forward and reverse primers. A genetic distance matrix was constructed using the HKY85 model of nucleotide evolution and potential phylogenies were assessed using maximum parsimony, maximum likelihood, and distance methods. Outgroup comparison was performed using a Coluber Constrictor cytochrome b sequence obtained from GenBank. The phylogenetic analysis revealed that the F. abacura specimens in this study fell into two distinct clades that correspond to the currently recognized subspecies, F. a. abacura and F. a. reinwardti. The genetic distance analysis revealed low intrapopulation genetic divergence, but a large (7.5%) interpopulation variation that suggests long-term genetic isolation of the two clades. The climatic history of the southeastern United States and the genetic variation observed in other vertebrate species support a hypothesis that Pleistocene glaciations divided the F. abacura population.