Proximate mechanisms leading to large male-mating advantage in the Andrew's toad, Bufo andrewsi

Abstract

AbstractIn animals, body size is a prominent trait that generally positively affects ecological and reproductive success. Through field observations and experiments, we investigated the effects of two mechanisms of sexual selection on large male mating advantage in the Andrew's toad, Bufo andrewsi, a species widely distributed in western China. We observed a large male mating advantage in the field. Field data were corroborated by experiments in which large males mated more frequently than smaller males. However, in female preference tests, in which females could choose freely between two males differing in body size, choosing females showed no size preference while many females did not exert mate choice at all. We suggest that the large male mating advantage observed in the field and laboratory is caused by competition among males rather than by female choice.