Divergent mechanisms of acoustic mate recognition between closely related field cricket species ( Teleogryllus spp.)

Effective recognition of conspeci fi c mating signals reduces the risk of maladaptive hybridization. Dis- secting the signal recognition algorithms that underlie preferences is a useful approach for testing whether closely related taxa evaluate the same or different signal features to achieve mate recognition. Such data provide information about potential constraints and targets of selection during evolutionary divergence. Using a series of mate choice trials, we tested whether closely related, but genetically and phenotypically divergent, fi eld cricket species ( Teleogryllus oceanicus and Teleogryllus commodus ) use shared or distinct recognition algorithms when evaluating acoustic male calling songs. These species overlap in sympatry, show premating isolation based on female discrimination of male calling songs, yet are capable of producing hybrid offspring. Unexpectedly, female selectivity for features of male song differed between the two species. We found that the two species use a combination of shared and unique signal fi ltering mechanisms, and we characterized how information about male carrier frequency, pulse rate and temporal patterning is integrated to achieve song recognition in each species. These results illustrate how comparatively few, simple modi fi cations in key components of signal recognition algo- rithms can lead to striking interspeci fi c discrimination between closely related taxa, despite apparent signal complexity. The fi nding that some steps during signal recognition and fi ltering are shared between the species, while others differ, can help to identify behavioural traits targeted by selection during evolutionary divergence