An RAPD (random amplified polymorphic DNA) analysis of genetic population structure of Balea biplicata (Gastropoda: Clausiliidae) in fragmented floodplain forests of the Elster/Saale riparian system

Eight German populations of the land snail Balea biplicata(Mollusca: Clausiliidae) were studied using the randomly amplified polymorphic DNA-polymerase chain reaction and morphometrics (principal component and discriminant analysis) to examine population structure and gene flow patterns in a fragmented landscape mosaic along the Elster/Saale riparian system, Germany. A variety of population genetic analyses targeting either more on the geographic scale of gene flow (genetic distances, F statistics, Mantel test) or on local genotypic structure (heterozygosity, linkage disequilibrium, bottleneck probability) showed that (1) the population system in total is governed by high gene flow independent of geographic distance, (2) genetic structure on the narrower sampling scale is mainly determined by stochastic processes due to genetic drift in small isolated and frequently recolonized populations, and (3) the morphometrical variation of the populations was related neither to habitat nor to genetic heterogeneity. The potentials for active and passive dispersal capacity of the snails and possible environmental impacts on their population structure are discussed.