Comparative molecular phylogeography of North American softshell turtles (Apalone): Implications for regional and wide-scale historical evolutionary forces

We use a comparative analysis of partial cytochrome b sequences to evaluate the evolutionary forces shaping wide-scale phylogeographic patterns of all three North American softshell turtles (Apalone ferox, A. mutica, and a. s pinifera). The overall phylogeographic patterns are concordant with results from both extensive regional studies of southeastern species, implicating historical vicariant processes during the Pliocene and Pleistocene, and inv estigations of more northerly distributed species, indicating a bottleneck effect of recent dispersal into postglacial habitat. We also resolved a nov el, shared genetic break between northern-western and southeastern populati ons within both A. mutica and A. spinifera, demonstrating the value of usin g widespread taxa to evaluate both regional and wider scale phylogeographic patterns. The extensive phylogenetic structure and sequence divergences wi thin both a., mutica and A. spinifera contrast sharply with most previous s tudies of turtles and with the hypothesis that turtles in general have slow rates of mtDNA evolution. (C) 2000 Academic Press.