AbstractMale Plathemis lydia defend mating territories along the perimeter of ponds. Females come to ponds for brief periods of time every few days to oviposit. During these visits, females actively discriminate among males, rejecting up to 48.9 % of mating attempts. Males varied significantly in the proportion of attempts successfully leading to copulation. However, males that obtained more matings also experienced more rejections. Extensive analyses based on absolute male size, relative male size, and male size relative to female size yielded only marginally significant evidence of female mate preference based on body mass, wing length, wing loading index, or age; to the extent that any of these characters appeared to influence mating success, they similarly influenced refusal rates. The overall weakness of female mate choice is further suggested by the frequency of females ovipositing without prior matings and by the low frequency with which females remate with the same males. On a population basis, females strongly prefer to oviposit in the middle of the day and at particular parts of the study pond. Thus, females exhibit strong choice at several levels. However, despite the high incidence of active female rejection and high variance in male mating success, mate choice is apparently of minor importance in this population. Female discrimination of males, combined with variance in male mating success, are necessary but not sufficient for the action of sexual selection via mate choice. These findings support the prediction that male-male competition is of primary importance in resource control mating systems in which males are able to control female access to most or all favored oviposition sites. However, it is not clear why females generally fail to discriminate among males, given that they have the opportunity to do so. In general, females appear to have low motivation to mate with males, presumably because multiple mating does not significantly increase their fertility or fecundity. Selection for rapid mating may be significant, both because of predation on females during mating and oviposition and because of the risks for males of losing their territories during mating bouts. This time constraint may be the most important factor limiting female discrimination among males on the basis of consistent characteristics.
Limited genetic variation for male mating success reveals low evolutionary potential for thermal plasticity in Drosophila melanogaster
