Simulated Predation Risk Influences Female Choice in Túngara Frogs, Physalaemus pustulosus

Abstract

While the presence of predators can influence female mate choice, few studies have investigated how females respond to quantitative variation in predation risk. In addition, we know little of how females respond to multiple, independent cues of risk. In this study, we investigated the effects of simulated predation risk on mate choice in tungara frogs, Physalaemus pustulosus, using the advertisement calls of predatory frogs, variation in ambient light, and simulated distance. Females showed aversion to conspecific calls associated with the calls of predators, and females were significantly less likely to travel perceived longer distances while the calls of predatory frogs were broadcast. In both the laboratory and field, females chose among potential mates significantly faster under higher light levels. Female responses to acoustic cues of predation risk were significantly influenced by light level, but decisions about travel distances were not. These results demonstrate that female choice is strongly influenced by perceived predation risk and that females can simultaneously evaluate quantitative variation in different cues of pre- dation risk. The changes in search behavior and mate evaluation we demonstrate indicate that predation plays a strong role in limiting signal evolution and possibly reproductive isolation.