Evidence for adaptive male mate choice in the fruit fly Drosophila melanogaster

Abstract

Theory predicts that males will benefit when they bias their mating effort towards females of higher reproductive potential, and that this discrimination will increase as males become more resource limited. We conducted a series of experiments to test these predictions in a laboratory population of the fruitfly, Drosophila melanogaster. In this species, courtship and copulation have significant costs to males, and females vary greatly in fecundity, which is positively associated with body size. When given a simultaneous choice between small and large virgin females, males preferentially mated with larger, more fecund, females. Moreover, after males had recently mated they showed a stronger preference for larger females. These results suggest that male D. melanogaster adaptively allocate their mating effort in response to variation in female quality and provide some of the first support for the theoretical prediction that male stringency in mate choice increases as resources become more limiting.

Figure 1

The difference in the per cent females mated (mean±s.e. of the percentage of large females mated−percentage of small female mated) by male D. melanogaster. Data are for (a) a ‘primary experiment’, where males were either ‘non-resource-depleted’ or ‘resource-depleted’ and (b) a ‘follow-up experiment’, where males were only ‘resource-depleted’. For each experiment, data are displayed both collectively and separately within each experimental block (day).