Adaptive Variability of the Frog Call Oscillator Provides Advantages for Communication in Noise

Most frogs and toads are vocal. The neural circuitry in the frog brain responsible for triggering a sequence of calls has been identified and termed the call oscillator. Early analyses of frog vocalizations have typically characterized frog calls as repetitive, stereotyped, species-specific, and unchanging within and between one individual's call to the next [1]. Here I provide six counter-examples of frog vocalizations that do not conform to these standards of stereotypy and thus bring to the fore the importance of inherent variation in frog communication signals and dispel the notion of frogs as tightly controlled genetic machines that produce fixed, identical, and repetitious calls. The purpose of frog call variation and the novel role of random processes in the generation of frog vocalizations are discussed.