Behaviour 2019
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Newly Evolved Rattling Crickets Use Novel Morphology to Attract Mates While Evading Eavesdroppers
James / H Gallagher, David / M Zonana, E / Dale Broder, Robin / M Tinghitella. University of Denver, Denver, CO, United States

Change in sexual signals drives diversification, but the early stages of this process remain elusive, as observing the origins of novel signals in real time is exceptionally rare. The recent appearance of new sexual signals in Hawaiian populations of the Pacfic field cricket provides an opportunity to study signal origins. Over ~20 years, wing morphology has changed repeatedly, leading to males that are silent or produce attenuated song, protecting them from an acoustically orienting parasitoid. Here, we describe the most recently discovered morph, rattling, which produces songs distinct from other Hawaiian morphs and is now locally dominant at one site. Using traditional landmarking, rattling wings do not differ from ancestral wings, despite clear song differences. However, microscopy revealed a novel modification to one sound-producing structure that exists only in rattling males. Further, rattling appears to be a private mode of communication among crickets. Our findings suggest that multiple evolutionary solutions to shared selective pressures have arisen and spread in this system in a short period of time, providing a microcosm to observe real-time signal diversification.