Genetic variation in natural island populations of members of the Drosophila nasuta and Drosophila ananassae subgroups.

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Abstract
Enzyme variations were investigated using wild-caught flies of 2 Drosophila species from South Pacific islands. For the majority of the enzyme systems analyzed, there were 2 or 3 alleles with high frequencies (5% or more in some populations) which accounted for 99% of the total, and the remainder was shared by 1 or more alleles with extremely low frequencies. However, there were systems for which either only 1 major allele existed with a series of low-frequency alleles or no variation was detected. The genetic diversity among the populations within and between the Samoa and Fiji island groups was investigated, using the frequencies of majority alleles in each species. The diversity was highly significant between the island groups, while there was only 1 enzyme system showing significant divergence of allele frequencies among islands within each group. The heterozygosity for the enzyme systems studied was determined, ranging from 51% to less than 1%, with a few esterase bands showing no variation. The population divergence revealcd by an analysis of variance of the degrees of heterozygosity paralleled the findings from the analysis of variance of major allele frequency, except that the within-region variation among islands was slightly greater with the heterozygosity analysis.