Plasticity in female mate choice associated with changing reproductive states

Flexibility in female mate choice occurs over a range of timescales. We examined this plasticity over the course of a single breeding cycle using phonotaxis tests that assay acoustic-based mating preferences of female túngara frogs, Physalaemus pustulosus. Tests were performed throughout three reproductive stages: unamplexed, amplexed and postmated. We tested whether the approach of the time at which a female needs to release her eggs (i.e. amplexed stage) influences her mate decisions. We examined three aspects of female mate choice behaviour: receptivity, permissiveness and discrimination. We considered a female receptive if she accepted a conspecific male's call, permissive if she accepted a call that was less attractive than a conspecific call and discriminating if she maintained her preference for a ‘whine-chuck’ over a ‘whine’. Our results show that the proportion of females responding receptively and permissively peaks during the amplexed stage. Individual females also increase receptive and permissive responses in the amplexed stage. Furthermore, time to respond to mate signals is lowest in the amplexed stage. The increase in permissive mate decisions was not associated with a decrease in the probability of expressing discriminatory behaviour. We suggest that the increase in permissive mate choice is due to a decrease in female choosiness, that is, a lowering of her threshold for accepting unattractive calls, as her receptivity increases. This study provides empirical support for theoretical models predicting that females will reduce their threshold criteria for choosing mates as critical time points approach.