Female treefrogs do not avoid heterospecific calls as they approach conspecific calls: implications for the mechanisms of mate choice

Because male treefrogs indiscriminately try to mate with other frogs of comparable size that move close to them, a major cause of heterospecific matings is thought to be inadvertent contact between a female of one species and a vocalizing male of another species. It follows that the probability of such mismatings would be reduced if females recognized the calls of sympatric, heterospecific males and avoided moving near those males during phonotactic approaches to vocalizing conspecific males. Gravid female treefrogs of three species were tested in situations in which they could avoid a source of heterospecific calls as they responded to conspecific calls. The results of these experiments provide no evidence that females avoid sources of heterospecific calls. Because females of all three species sometimes show positive phonotactic responses in 'no-choice' situations to the same kinds of heterospecific calls used in this study, these results suggest that the mechanisms responsible for homospecific pairing are qualitatively no different than those mediating intraspecific mate choice. The implications of these results for current debates about processes underlying mate choice are discussed