KATYDID SYNCHRONOUS CHORUSING IS AN EVOLUTIONARILY STABLE OUTCOME OF FEMALE CHOICE

IN many animals that use rhythmic acoustic or bioluminescent sexual communication, neighbouring males precisely synchronize their signals1-4. This event has previously been interpreted as a development whereby cooperative individuals benefit from maintenance of species-specific signalling rates5,6, minimization of pre dation risks7,8, or maximization of peak signal amplitude of a local population2,9. Our recent findings on chorusing in the neotropical katvdid Neoconocephalus spiza (Orthoptera: Tettigoniidae), however, refute for this species all three hypotheses that claim that synchrony is adaptive. Instead, we demonstrate that synchrony can be an epiphenomenon created by competitive interactions between males jamming each other's signals. The mechanism generating this interference is shown to be an evolutionarily stable strategy (ESS) maintained under sexual selection for exploiting a critical psychoacoustic feature: females orienting toward signalling males choose the leading call in a closely synchronized sequence.