A population genetic analysis of the midget faded rattlesnake in Wyoming

Little is known about the population biology of midget faded rattlesnakes, a sensitive subspecies of the Western Rattlesnake, despite conservation efforts to protect them. We conducted a molecular genetic study of midget faded rattlesnakes in southwestern Wyoming to investigate population genetic structure in this area, particularly with reference to Flaming Gorge Reservoir and its associated human activities, and to document levels of genetic diversity. We genotyped 229 snakes from 11 sampling sites using 9 microsatellite loci. We found significant levels of genetic structure among sites that were better explained by geographic region and isolation by distance than by position relative to waterways. Sites on either side of the reservoir at its widest point were not significantly different. Six of the sites showed signatures of a population bottleneck using an alpha value of 0.05. Three of these bottlenecked sites (the three most northern) were the most genetically distinct and occur in areas of greatest impact from human activity.