Alcohol reduces choosiness and relaxes mate preferences in female Drosophila simulans

Alcohol can alter sexual behaviour. However, our understanding of alcohol's effects on sexual interactions is limited because males are usually the focus of nonhuman studies. Alcohol could in theory alter female mate-choice and, in turn, affect sexual selection, a major mechanism of evolution. Here we tested whether alcohol exposure affected female mate-preference, choosiness, and copulation duration in the fly Drosophila simulans, while simultaneously testing for genetic variation in these effects. We found that alcohol exposure did not affect copulation duration, but did weaken mate-preference, as females copulated with a broader range of males after exposure, and it tended to reduce female choosiness as females mated more quickly. Although female genotype significantly affected copulation duration and choosiness, the effects of alcohol appeared to be reasonably consistent across genotypes, but this depended on the analysis employed. Nonetheless, alcohol reduced female choosiness and weakened mate-preference, and may therefore reduce the strength of sexual selection. Testing whether these changes impact female fitness is now required.