Consistency of female choice in the túngara frog: a permissive preference for complex characters

Previous phonotaxis experiments in the túngara frog,Physalaemus pustulosus, indicated a permissiveness in female preference that allows sexually selected complex call characters to be replaced with various alternative characters. Although they prefer complex to simple calls, females as a group did not discriminate between several alternative complex characters appended to the simple conspecific call. However, these studies did not address the possibility that the apparent permissiveness in female preference occurred because of an averaging of population data. The observed patterns in female preference could result from all females finding a certain set of call variants equally attractive, or from a polymorphism in female call preference. To discriminate between these two alternatives, consistency of mate choice was determined for three pairs of calls that elicited no phonotactic bias in population studies. Individual females did not repeatedly choose one stimulus of a pair over the other, demonstrating that the patterns of permissiveness observed in the population are paralleled by similar patterns within females. A broad preference for complex calls in theP.pustulosusspecies group would permit the evolution of sexually selected call variation through sensory exploitation.