Print Page Metapopulation theory predicts increasing genetic differentiation between populations as a function of distance (isolation). The blanket application of metapopulation theory has received some criticism because there can be significant differences in dispersal behaviors among species. This is particularly true for amphibians, which vary dramatically in vagility. We used two syntopic amphibian species that breed in a common set of wetlands, but differ in putatitve dispersal capabilities, to test whether patterns of genetic differentiation suggest similar metapopulation structure across the same spatial scale. A total of 219 Rana sphenocephala, which is a moderately-sized and highly mobile frog, and 274 Eurycea quadridigitata, a small salamander with presumably limited dispersal ability, were collected from 10 and 8 isolated wetlands, respectively, located on an 11,800 ha habitat preserve located in Baker County, Georgia. Surveyed wetlands were separated by as little as 0.8 km and as much as 12.1 km. Both species were screened at 12 microsatellite loci.
Results/Conclusions
For R. sphenocephala, we found little to no differentiation (FST values ranged from 0.000 to 0.025) among wetlands, with the exception of the most remote site, which was moderately differentiated from all other wetlands (FST values ranged from 0.091 to 0.111). In E. quadridigitata, populations were generally highly differentiated (FST values ranged from 0.024 to 0.539). Based on our results, we believe that R. sphenocephala may follow a metapopulation model only at large spatial scales (e.g. when wetlands are at least 12 km apart). In contrast, Eurycea quadridigitata, exhibits metapopulation model at a fine scales, but are functionally separate populations at the metapopulation scale of R. sphenocephala. These patterns suggest that population structure can differ dramatically among syntopic amphibian species consistent with differences in dispersal ability between species.
