Geographic variation in the matching between call characteristics and tympanic sensitivity in the Weeping lizard

Effective communication requires a match among signal characteristics,
environmental conditions, and receptor tuning and decoding. The degree of
matching, however, can vary, among others due to different selective
pressures affecting the communication components. For evolutionary
novelties, strong selective pressures are likely to act upon the signal
and receptor to promote a tight match among them. We test this prediction
by exploring the coupling between the acoustic signals and auditory
sensitivity in Liolaemus chiliensis, the Weeping lizard, the only one of
more than 285 Liolaemus species that vocalizes. Individuals emit distress
calls that convey information of predation risk to conspecifics, which may
respond with antipredator behaviors upon hearing calls. Specifically, we
explored the match between spectral characteristics of the distress calls
and the tympanic sensitivities of two populations separated by more than
700 km, for which previous data suggested variation in their distress
calls. We found that populations differed in signal and receptor
characteristics and that this signal variation was explained by population
differences in body size. No precise match occurred between the
communication components studied, and populations differed in the degree
of such correspondence. We suggest that this difference in matching
between populations relates to evolutionary processes affecting the
Weeping lizard distress calls.