The mechanism of sound production in túngara frogs and its role in sexual selection and speciation.

Sexual communication can evolve in response to sexual selection, and it can also cause behavioral reproductive isolation between populations and thus drive speciation. Anurans are an excellent system to investigate these links between behavior and evolution because we have detailed knowledge of how neural mechanisms generate behavioral preferences for calls and how these preferences then generate selection on call variation. But we know far less about the physical mechanisms of call production, especially how different laryngeal morphologies generate call variation. Here we review studies of a group of species that differ in the presence of a secondary call component that evolved under sexual selection. We discuss how the larynx produces this call component, and how laryngeal morphology generates sexual selection and can contribute to speciation.