HUMFELD, Sarah C; University of Missouri-Columbia: Male-male competition mediates the mating tactic switch in Hyla cinerea

An important example of phenotypic variation is alternative behaviors used for mate acquisition. Alternative reproductive behaviors are usually considered to be a consequence of male-male competition for a limited number of females, in which only a subset of males can successfully employ the dominant mating tactic. Animals that conditionally switch between alternative mating behaviors over a short time period provide an opportunity to study the role of social factors in mediating this decision. Male green treefrogs (Hyla cinerea) produce acoustic signals to attract females; however, some silent males adopt the satellite mating tactic, whereby they attempt to intercept females attracted to nearby calling males. Individual males can utilize both reproductive tactics within or between nights, and may switch in response to nearby acoustic stimuli. Chorusing results in competition among neighbors, so we predict that males will adaptively adopt tactics in response to the advertisement calls of neighbors of varying quality. To determine whether relative detectability (intensity) and attractiveness (frequency) mediate the decision to switch mating tactics, I conducted two field playback experiments in which I observed the calling and mating tactic behaviors of males confronted with low- and high-frequency signals of varying intensity. The results indicate that relative competitive ability is an important determinant of mating tactic adoption in green treefrogs.