The Variability and Malleability of Frog Call-Timing Mechanisms are Neglected in Traditional Call-Timing Models

Males of many insect and anuran species send courtship calls to females from within crowded chorusing aggregations. Despite large phylogenetic distances between insects and frogs, many convergences in communication behavior are evident due to similar selection pressures arising when competing acoustically within choruses. Consequently, mechanistic call-timing models and theoretical frameworks originally derived from work on synchronizing insects have been applied fruitfully to alternating frogs. However, despite such similarities, there exist extensive differences in the details of the communication ecologies and nervous systems of these taxa, suggesting interesting differences may have been overshadowed by these broad similarities. Here, we synthesize recent findings regarding the call-timing mechanisms of túngara frogs, a species showing flexible calling interaction patterns across varied chorusing environments. Based on these findings, and hints present in other frogs, we suggest that the unique demands arising within the dense choruses frogs form have selected for call-timing mechanisms whose parameters are highly flexible, and malleable moment-to-moment in response to complex stimulation patterns arising in varied acoustic environments. Such fine-scale malleability and responsiveness to external stimulation are neglected in traditional theoretical models of call-timing mechanisms, possibly because the resulting variability would be detrimental to the highly structured interaction patterns of the synchronizing insects from which much of this work derives. Though further experiments are needed to fully vet our broader claims, we hope to inspire researchers to consider previously neglected factors influencing call-timing responses and chorusing dynamics, and to complement the impressive work on similarities across chorusing taxa with additional details on finer differences.