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

Snakes are a particularly threatened vertebrate taxon, with distributions of many species and populations becoming increasingly fragmented. At present, little is known about the degree of genetic differentiation that exists between isolated populations even though such information may be critical to their survival and conservation. As an example of how recently developed RAPD genetic markers can be used in conservation genetics, we present preliminary results from a study which used these DNA-based markers to assess population divergence in two threatened Canadian snakes, the black rat snake (Elaphe o. obsoleta) and the eastern massasauga rattlesnake (Sistrurus c. catenatus). We present information on the levels of variation and reliability of amplification for fragments generated from five primers. We then use a recently developed analytical technique to estimate levels of nucleotide diversity within populations and sequence divergence between populations. Our results show that intrapopulation levels of divergence as estimated by the methods of Clark and Lanigan (Molecular Biology and Evolution 1993, 10, 1096-1111) approximate those found far mtDNA in vertebrates and that diversity between snake populations is small and non-significant when tested using randomization procedures. Thus, our study provides an example of how RAPDs can be applied to conservation genetic studies of vertebrates and suggest that the snake populations we examined have only recently become isolated and may be considered genetically equivalent from a conservation perspective, although this conclusion needs to be confirmed with other DNA-based markers.