Genotypic differences in mating success and the maintenance of the alcohol dehydrogenase polymorphism inDrosophila melanogaster: No evidence for overdominance or rare genotype mating advantage

Abstract

Strains of Drosophila melanogaster having different alcohol dehydrogenase (Adh) genotypes (FF, FS, or SS) were assembled in a mating chamber in varying ratios, and the mating successes were recorded. In experiments with a 25:25 ratio, the FF males succeeded in mating more than did FS and SS males, while the FS males surpassed the SS males. As for the females, FF also surpassed SS. In experiments with a 5:45 or 45:5 ratio, some differences from the 25:25 ratio occurred, but in these cases the rare genotypes were at a disadvantage. In one case, female genotypes (FF vs. SS) displayed a difference in mating latency time, but male genotypes did not. The findings did not suggest that rare genotype mating advantage and overdominance in mating success play a role in the maintenance of the Adh polymorphism.

Environment-dependent fitness differences in Drosophila melanogaster: temperature, domestication and the alcohol dehydrogenase locus

“…A related laboratory study indicated that male heterozygotes mated more frequently with vigin females than did either homozygote (McKenzie and Fegent, 1980). Differences in mating abilities of flies of different Adh genotype have also been detected by Pot et aL (1980) and Knoppien eta!. (1980).…”

Effects of rearing conditions and age on the difference in mating success between alcohol dehydrogenase genotypes of Drosophila melanogaster

“…Rearing conditions and age of the flies were varied. The large mating advantage of FF for 4-6 days old flies, reared at 25°C, found by Pot et al (1980), was confirmed. This advantage decreased or even disappeared when rearing temperature or age of the flies was lowered.…”

“…These strains and also the food they were reared on were the same as in Pot et al (1980). Parents of the flies used in the experiments remained in bottles to lay eggs for 3 days (at 20°C for 5 days), each bottle containing 15 pairs.…”

“…Thus the mating behaviour of the genotypes seemed to act against the establishment of an equilibrium. It is doubtful, however, whether this conclusion can be generalized to flies reared under conditions different from those used by Pot et al (1980), as mating success can be influenced by various environmental factors (see for a review: Spiess, 1970). For instance, the difference in mating speed between different karyotypes of Drosophila pseudoobscura (Spiess et al, 1966) and Drosophila persimilis (Spiess & Spiess, 1967) varies with rearing temperature.…”

“…Recently, the role of mating behaviour in the maintenance of the Adh polymorphism was investigated by Pot et al (1980). They found no evidence for rare genotype mating advantage or overdominance in mating success which might account for the stable equilibrium.…”