High Evolutionary Potential Maintained in Common Frog (Rana temporaria) Populations Inhabiting Urban Drainage Ponds

Abstract

Urbanisation leading to habitat change and fragmentation is a recognised global threat to biodiversity. However, it may also offer opportunities for some species. Genetic diversity, one of the three components of biodiversity, is often overlooked in conservation planning and policy. In the present study, we used a panel of seven microsatellite markers to compare the genetic structure of 34 common frog (Rana temporaria) populations residing in urban and suburban drainage ponds in Inverness (Scotland) with populations from rural surroundings. As a main finding, the levels of genetic variation were indiscernible between (sub)urban and rural populations. Significant isolation-by-distance was observed only for rural populations, with measures of pairwise genetic differentiation (F_st) that were, on average, lower than those in urban and suburban areas. The mean numbers of alleles remained stable between two temporal sets of samples collected at intervals broadly representing one R. temporaria generation, but with a tendency of decreasing allelic richness, irrespectively of the site characteristics. Taking these results together, our study revealed that the elevated levels of differentiation between R. temporaria populations inhabiting (sub)urban drainage ponds did not lead to increased levels of genetic erosion. Our findings support the importance of well-designed blue–green infrastructure in urban landscapes for the retention of within-species genetic diversity and can help to inform future biodiversity management policies.