Trade-off in short- and long-distance communication in tungara (Physalaemus pustulosus) and cricket (Acris crepitans) frogs

Female phonotaxis in túngara(Physalaemus pustulosus)and cricket (Acris crepitans) frogsis biased toward male advertisementcalls or call components of lowerfrequency. This behavioralbias might result in part from a mismatch betweenthe spectralcharacteristics of the advertisement call and the most sensitivefrequencyof the peripheral end organ implicated in reception of thesesounds.In both species, females are tuned to frequencies lowerthan average for thecalls in their population. This mismatch,however, represents the situationduring short-distance communication.Female frogs can also use the call todetect choruses at longdistances, and the spectral distribution of callenergy canvary with transmission distance. We used computer simulationstotest the hypothesis that there is a better match betweentuning and callspectral energy at long distances from the callingmale than at shortdistances by comparing the performance (soundenergy received) of the naturaltuning curve relative to anoptimal tuning curve (i.e., one centered at thecall's dominantfrequency). The relative performance of the natural tuningcurveincreased with distance in túngarafrogs. For the twosubspecies of cricket frogs, however, the relativeperformancedecreased at longer distances. The performance did not equaltheoptimal tuning curve at the distances tested. The resultsindicate that therelationship between calls and auditory tuningcannot be optimal for both longand short distance reception.The relationship between female tuning and calldominant frequencymay represent a compromise between short and long distancecommunication,and the bias toward short or long distances may vary amongspecies.