Molecular and chromosomal polymorphism in continental and insular populations from the southwestern range of Drosophila subobscura

Eight insular and continental populations from the south-western range of Drosophila subobscura have been studied with regard to molecular and inversion polymorphisms. Heterogeneity between populations with respect to allele frequencies of 4 gene loci (Amy, Est-8, Est-9 and Pep-1) is the highest known for natural populations of the species. Moreover, the most common allele for these loci is not the same in all populations. Cladograms based on UPGMA clustering of the genetic distances based on allele frequency do not coincide with those constructed with inversion data. The allele-frequency differences between the populations may be due to non-random associations between enzyme alleles and gene arrangements and to founder effects appearing in the insular populations.