Population genetics of the Halys pit viper (Gloydius halys) at the northern distribution limit in Siberia

We studied the genetic structure and diversity of a vulnerable population of the Halys pit viper ( Gloydius halys ) living at the northern distribution limit of the species (Novosibirsk Region, West Siberia, Russia) and fairly isolated from the nearest known locations (180-200 km). 157 snakes from three locations (separated by 5-11 km) were genotyped using 8 microsatellite loci. In addition, nucleotide sequences of a mitochondrial marker gene (ND4) were obtained from 30 individuals. Two mitochondrial haplotypes differing by one synonymous substitution could be detected. Haplotype H1 had a prevalence of 96.7%. High levels of genetic diversity (mean ) were detected and no evidence of a recent bottleneck in any sampling site could be discovered. We found that G. halys exhibits a low, although significant, level of genetic differentiation on a fine geographic scale (overall F ST = 0.013). The degree of differentiation is comparably low with regard to values reported for other vipers and more similar to those in Colubridae. In addition, using local based F ST estimates, we detected a significant difference in the extent of genetic drift between the centrally located and marginal local populations as predicted by the stepping-stone model of migration. Thus, from a short-term perspective, primary attention should be given to the peripheral local populations, due to limited immigration and stronger influence of genetic drift. Since all habitat patches are situated along the river and have a linear order it is important to preserve each habitat site to maintain gene flow across the metapopulation.