Population genetic structure of Blanding's turtles (Emydoidea blandingii) in an urban landscape

Recent investigations of Blanding's turtles Emydoidea blandingii in urban landscapes in the Greater Chicago metropolitan area (GCMA) indicate that populations are small and isolated. This led to the prediction that two local populations of Blanding's turtles in the GCMA would have less within-population genetic variation than larger populations in Michigan, Nova Scotia, and Wisconsin. We further predicted that Blanding's turtles in Nova Scotia would be genetically differentiated from those in the species' main range. We tested these predictions using variation in randomly amplified polymorphic DNA. Levels of genetic variability as measured by percent polymorphism and mean percent band sharing were similar among populations in the GCMA, Nova Scotia, and Wisconsin, though genetic variation in Michigan was significantly higher. No unique bands were detected in GCMA, however, 16 were found in Michigan, five in Nova Scotia, and one in Wisconsin. As predicted, Blanding's turtles in Nova Scotia, which have been geographically isolated from the species' main range for 4000-8000 years, were genetically differentiated from all other populations in the study. Although it was not clear that recent isolation and population declines resulted in a loss of genetic variation, our results indicated that Blanding's turtles in the GCMA may be genetically depauperate. The use of management interventions to prevent the loss of genetic diversity in the GCMA is discussed.