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

Strains ofDrosophila 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 2525 ratio, theFF males succeeded in mating more than didFS andSS males, while theFS males surpassed theSS males. As for the females,FF also surpassedSS. In experiments with a 545 or 455 ratio, some differences from the 2525 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 theAdh polymorphism.