COMPARATIVE POPULATION STRUCTURING OF MOLECULAR AND ALLOZYME VARIATION OF DROSOPHILA-MELANOGASTER ADH BETWEEN EUROPE, WEST-AFRICA AND EAST-AFRICA

Restriction enzyme molecular variation in Drosophila melanogaster Adh was compared between three natural populations from Europe, West Afric a and East Africa. The frequency distribution of silent variation in t he slow allele was compatible with the neutral model in all three samp les. The number of haplotypes in East Africa was significantly higher than in the other two populations. The largest divergence, as measured by F-st, was between the East African population and a group made up from the West African, the European, and previously studied American p opulations. We suggest that a split first occurred within African popu lations at least 44000 years ago. European populations separated from West Africa more recently, between the last glacial maximum and the po st-glacial optimum, 18 000 to 8000 years ago. We suggest that this spe cies was domesticated recently relative to human evolution, possibly w ith the advent of agriculture. Population differentiation with respect to the two allozymes, fast and slow, does not follow the geographical pattern of silent variation. It opposes European to both African popu lations, and probably results from selection for adaptation to alcohol in recent temperate populations.