GENETIC-ANALYSIS OF POPULATIONS OF THREATENED SNAKE SPECIES USING RAPD MARKERS

Snakes are a particularly threatened vertebrate taxon, with distributi ons of many species and populations becoming increasingly fragmented. At present, little is known about the degree of genetic differentiatio n that exists between isolated populations even though such informatio n may be critical to their survival and conservation. As an example of how recently developed RAPD genetic markers can be used in conservati on genetics, we present preliminary results from a study which used th ese DNA-based markers to assess population divergence in two threatene d Canadian snakes, the black rat snake (Elaphe o. obsoleta) and the ea stern massasauga rattlesnake (Sistrurus c. catenatus). We present info rmation on the levels of variation and reliability of amplification fo r fragments generated from five primers. We then use a recently develo ped analytical technique to estimate levels of nucleotide diversity wi thin populations and sequence divergence between populations. Our resu lts show that intrapopulation levels of divergence as estimated by the methods of Clark and Lanigan (Molecular Biology and Evolution 1993, 1 0, 1096-1111) approximate those found far mtDNA in vertebrates and tha t diversity between snake populations is small and non-significant whe n tested using randomization procedures. Thus, our study provides an e xample of how RAPDs can be applied to conservation genetic studies of vertebrates and suggest that the snake populations we examined have on ly recently become isolated and may be considered genetically equivale nt from a conservation perspective, although this conclusion needs to be confirmed with other DNA-based markers.