Asymmetric Response to Heterotypic Distress Calls in the Lizard Liolaemus chiliensis

Abstract

The weeping lizard, Liolaemus chiliensis, emits distress calls when trapped by a predator. Conspecific lizards respond to such calls with prolonged immobility, which may increase their probability of remaining undetected by a predator. This benefit, however, depends on the ability to react to the alert message of the call, which may be impaired by natural variation in the calls. The distress calls of L.chiliensis show geographic variation, and here we tested the response of two geographically distant populations (>700km apart) to local (homotypic) and non-local (heterotypic) distress calls; if populations are finely tuned to their local calls, they may not be able to respond to heterotypic calls. We found that geographic variation in calls affects the lizards' response, but this effect was population dependent; whereas southern lizards responded to calls of both populations, the northern lizards only reacted to homotypic distress calls. The factors that determine this asymmetric response to heterotypic calls are unclear and we discuss three hypotheses that have a common component in the difference in body size between the tested populations, which seems to play a key role in determining the response to distress calls in this species.