DNA-FINGERPRINTING REVEALS A LACK OF GENETIC-VARIATION IN NORTHERN POPULATIONS OF THE WESTERN POND TURTLE (CLEMMYS MARMORATA)

I used DNA fingerprinting to provide the first analysis of the genetic composition of western pond turtle (Clemmys marmorata) populations in Washington, Oregon, and California. Populations of the western pond t urtle in Washington and northern Oregon are rapidly approaching extinc tion. Genetic similarity within the largest northern populations which are located inland, is high. An analysis of population substructure ( F-st) revealed significant genetic divergence between inland populatio ns, indicating a lack of dispersal and gene flow between sites. In con trast, northern coastal sites are not genetically distinct, but there are few if any viable populations remaining in this region. Genetic va riability within southern California populations is a great deal highe r than in northern inland sites. Similarly, a low F-st value indicated a lack of genetic differentiation between southern sites. An inter-re gional analysis of population substructure (F-st = 0.24) revealed a si gnificant degree of genetic divergence between geographical regions th roughout the range. In addition, an estimate of western pond turtle ph ylogeny showed a genetic break in the species between northern and sou thern populations. Both population subdivision and phylogenetic analys es suggest a lack of appreciable gene flow between geographical region s for a considerable period of time. Genetic analyses support traditio nal subdivision based solely on the morphological variation of Clemmys marmorata into two subspecies: northern Clemmys marmorata marmorata a nd southern Clemmys marmorata pallida. Recovery of dwindling northern populations must combine demographic and genetic considerations. A fir st step should be to preserve local gene pools while augmenting popula tion numbers, with the goal of preventing the extinction of this genet ically and morphologically distinct subspecies.