Geographic variation of six allozyme loci in Drosophila melanogaster: an analysis of data from different continents.

Based on data from 70 literature sources, the frequencies of common alleles at six allozyme loci were examined in Drosophila melanogaster populations from five geographic regions: North America (including Central America), South America, Europe-Africa, Asia, and Australasia. The analyzed loci were Adh, Odh, Gpdh, G6pd, Pgd, and Est-6, which have been previously reported by other authors to show latitudinal variation in North America, Eurasia and Australasia. We found five parallel latitudinal clines for AdhF and three clines for GpdhS in five geographic regions as well as four clines for G6pdF, three clines for Est-6S, and two clines for OdhF and PgdF in four regions (data from South America for G6pd, Odh, Est-6, and Pgd were not available). Such pattern of variation confirmed the possibility that considered allozyme polymorphisms are maintained by climatic selection. Significant differentiation of mean allele frequencies among geographic regions was in agreement with current evidence on history of D. melanogaster worldwide dispersion.