Frequency and temperature dependent selection at the alcohol dehydrogenase-1 locus of Drosophila buzzatii

Abstract

Genotype frequencies at the alcohol dehydrogenase-1 (Adh-1) locus of D. buzzatii were analysed for deviations from Hardy-Weinberg equilibria in the progeny of laboratory populations established at five initial Adh-1" allele frequencies and kept at either 18°C, 25°C or 30°C. At 25°C, no observed genotype frequencies were significantly different from Hardy-Weinberg expectations. Observed frequencies of heterozygotes were generally less than expected for populations at 18°C and 30°C. Fitness differences among genotypes were greater in males than in females, with Adh-1' homozygotes having highest fitness at 18°C and AdIs-1' homozygotes having highest fitness at 30°C. The results are discussed in relation to previous field and laboratory studies on D. buzzatii and to the Adh polymorphism of D. melanogaster.