Genetic similarity as a measure for connectivity between fragmented populations of the moor frog (Rana arvalis)

Genetic differentiation among populations of the moor frog (Rana arvalis) w as tested on a spatial scale where some dispersal between populations is ex pected to occur, in a landscape in The Netherlands that has become fragment ed fairly recently, in the 1930s. Five microsatellite loci were used, with 2-8 alleles per locus. F-IS was 0.049 across loci. and most populations wer e in HW equilibrium. The degree of population subdivision was low (F-ST = 0 .052). A significant positive correlation between genetic distance and geog raphical distance was found, indicating a limitation in dispersal among pop ulations due to distance. To test the impact of the landscape mosaic on the connectivity between patches, distance measures were corrected for relativ e amounts of habitat types with known positive or negative influence on moo r frog dispersal. Notably, the resistance variable for the fraction of nega tive linear elements (roads and railways) gave a higher explanatory value t han geographical distance itself. Therefore, it is particularly the number of barriers (roads and railways) between populations that emerges as a fact or that reduces exchange between populations. It is concluded that genetic techniques show promise in determining the influence of landscape connectiv ity on animal dispersal.