MOLECULAR VARIATION OF ADH AND P6 GENES IN AN AFRICAN POPULATION OF DROSOPHILA-MELANOGASTER AND ITS RELATION TO CHROMOSOMAL INVERSIONS

Four-cutter molecular polymorphism of Adh and P6, and chromosome inver sion polymorphism of chromosome II were investigated in 95 isogenic li nes of an Ivory Coast population of Drosophila melanogaster, a species assumed to have recently spread throughout the world from a West Afri can origin. The P6 gene showed little linkage disequilibrium with the In(2L)t inversion, although it is located within this inversion. This suggests that the inversion and the P6 locus have extensively exchange d genetic information through either double crossover or gene conversi on. Allozymic variation in ADH was in linkage disequilibrium with In(2 L)t and In(2R)NS inversions. Evidence suggests either that inversion l inkage with the Fast allele is selectively maintained, or that this al lele only recently appeared. Molecular polymorphism at the Adh locus i n the Ivory Coast is not higher than in North American populations. Ne w haplotypes specific to the African population were found, some of th em connect the ''Wa(S)-like'' haplotypes found at high frequencies in the United States to the other slow haplotypes. Their relation with In (2L)t supports the hypothesis that Wa(S) recently recombined away from an In(2L)t chromosome which may be the cause of its divergence from t he other haplotypes.