The role of sex on behavioral responses to mating signals: studies of phonotaxis and evoked calling in male and female túngara frogs
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Signal detection theory predicts that costs associated with recognition errors, specifically failing to respond to relevant stimuli (missed detection) and responding to erroneous ones (false alarms), shape receiver permissiveness in animal communication systems. Fitness costs of missed detection and false alarms in response to sexual signals differ between the sexes, and are usually higher for females than males. This asymmetry in costs predicts that males should be more permissive than females in their responses to signals. In my dissertation I investigate the behavioral responses of male and female túngara frogs, Physalaemus pustulosus, to mating signals and sounds associated with such calls. Specifically I explore the following topics: i) responses of the sexes to call complexity, ii) perception of congeneric mating calls by males and females, iii) responses of males to the conspecific call compared to those of extant heterospecifics, iv) effect of sounds associated with increased predation risk in reproductive decisions, and v) effect of the task performed by each sex on signal permissiveness. My findings indicate that recognition errors are higher for males than females as predicted by the different costs associated with recognition errors for each sex. Males respond to a broader range of calls than females. Despite the differences, evolutionary history has left a footprint on the brain of both sexes. In addition, I found that females behaved more cautiously than males suggesting that the sexes balance the risk of predation and the cost of cautious mating strategies differently. In the mating system of túngara frog, as in many others, sexual signals elicit different tasks in the different sexes, female phonotaxis and male calling. Therefore, the sexual differences in decision making I found could be either sex-specific independent of task, or task-specific independent of sex. Here I show that sexual differences in receiver permissiveness are motivated by differences due to the typical reproductive tasks displayed by the sexes.