THE INFLUENCE OF LAND-USE ON THE GENETIC-STRUCTURE OF POPULATIONS OF THE COMMON FROG RANA-TEMPORARIA

In order to find out the influence of land use and topographic distance on the genetic structure of populations of the common frog Rana temporaria L. in the Saar-Palatinate lowlands (Federal Republic of Germany), tissue of larvae was examined by means of horizontal starch gel electrophoresis. A total of 24 loci coding for 14 different enzymes were studied. Genotype frequencies, allele frequencies and mean heterozygosity were calculated, and genetic distances using Nei's formula. Strong deviations from the Hardy-Weinberg equilibrium were found; the degree of homozygosity was higher than expected. Separation by highways reduced average heterozygosity as well as genetic polymorphism of local populations. One area surrounded by roads had high genetic distances to other sampling stations. A multiple regression analysis showed that motorways and railways have a significant (p = 0·03) barrier effect on frog populations within 3-4 km. Meadowland apparently enabled individual exchange in a range between 2 and 7 km. Consequences for the design of biotope systems are discussed. © 1990.