Genic variation in central and marginal populations of Drosophila subobscura

The genic variability at twenty loci in marginal, submarginal and central populations of Drosophila subobscura has been studied by starch gel electrophoresis. The samples from marginal populations orginate from Finland, the submarginal ones from Sweden and Denmark, whereas flies collected from France and northeastern Italy are taken to represent central populations. The average degrees of genic polymorphism are undifferentiated over the distribution area of D. subobscura. Most loci have fairly uniform allele frequencies in all populations. Local differences have been found at six loci. These fluctuations represent adaptations to local environmental differences.