Socially flexible female choice and premating isolation in field crickets (Teleogryllus spp.)

Social influences on mate choice are predicted to influence evolutionary divergence of closely related taxa, because of the key role mate choice plays in reproductive isolation. However, it is unclear whether females choosing between heterospecific and conspecific male signals use previously experienced social information in the same manner or to the same extent that they do when discriminating among conspecific mates only. We tested this using two field cricket sister species (Teleogryllus oceanicus and Teleogryllus commodus), in which considerable information is known about the role of male calling song in premating isolation, in addition to the influence of acoustic experience on the development of reproductive traits. We manipulated the acoustic experience of replicate populations of both species and found, unexpectedly, that experience of male calling song during rearing did not change how accurate females were in choosing a conspecific over a heterospecific male song during playback trials. However, females with acoustic experience were considerably less responsive to male song compared with naive females. Our results suggest that variation in the acoustic environment affects mate choice in both species, but that it may have a limited impact on premating isolation. The fact that social flexibility during interspecific mate discrimination does not appear to operate identically to that which occurs during conspecific mate discrimination highlights the importance of considering the context in which animals exercise socially flexible mating behaviours. We suggest an explanation for why social flexibility might be context dependent and discuss the consequences of such flexibility for the evolution of reproductive isolation.