Population structure and genetic diversity of Rana dalmatina in the Iberian Peninsula

The increasing fragmentation of natural habitats may strongly affect patterns of dispersal and gene flow among populations, and thus alter evolutionary dynamics. We examined genetic variation at twelve microsatellite loci in the Agile frog (Rana dalmatina) from 22 breeding ponds in the Iberian Peninsula, the southwest limit of its range, where populations of this species are severely fragmented and are of conservation concern. We investigated genetic diversity, structure and gene flow within and among populations. Diversity as observed heterozygosities ranged from 0.257 to 0.586. The mean number of alleles was 3.6. Just one population showed a significant F-IS value. Four populations show evidence of recent bottlenecks. Strong pattern of structure was observed due to isolation by distance and to landscape structure. The average degree of genetic differentiation among populations was F-ST = 0.185. Three operational conservation units with meta-population structure were identified. Additionally, there are some other isolated populations. The results reinforce the view that amphibian populations are highly structured even in small geographic areas. The knowledge of genetic structure pattern and gene flow is fundamental information for developing programmes for the preservation of R. dalmatina at the limits of its geographic distribution.