Spatial and genetic structure of a Lacerta viridis metapopulation in a fragmented landscape in Bulgaria

Numerous studies showed that habitat fragmentation can affect the constitution of species by impairing living conditions, impeding gene flow and thereby reducing genetic variability. However, populations of the same species may react less sensitive to fragmentation in the core than in the periphery of its distribution range. In the core they are assumed to be more euryoecious compared to the periphery, where they are assumed to be stenoecious with lower genetic diversity and higher genetic differentiation. We tested this hypothesis by comparing the genetic variability of 215 individuals of ten populations of Lacerta viridis from fragmented habitats within its distribution center in Bulgaria using genotype data of 19 microsatellite loci. We could not detect significant alteration of genetic variation, regardless of patch size and isolation by distance, indicating that fragmentation indeed did not have a strong impact on L. viridis in the core area of its historical and recent distribution range. We cannot rule out that the time elapsed since habitat fragmentation occurred was too short to yield a genetic response. However, in a similar study on L. agilis, which is stenoecious in Bulgaria, all genetic diversity indices declined with patch size. This provides indications that fragmentation at present does not have a strong effect on the genetic variation of Bulgarian L. viridis populations.