THERMAL ECOLOGY OF A LIOLAEMUS LIZARD ASSEMBLAGE ALONG AN ANDEAN ALTITUDINAL GRADIENT IN CHILE

We studied the thermal ecology of ten species of Liolaemus lizards on an altitudinal transect in the central Chilean Andes, from 1500 to 300 0 m elevation, to determine in the field how thermoregulatory factors may be setting distribution limits. All but one species had the same f ield body temperatures (za. 35 degrees C). The only exception was the higher body temperature of the darkly colored male L. nigroviridis, wh ich appears to result from the interplay of biophysical attributes wit h the social structure of this species. Most species of lizard selecte d microhabitats that allowed increased length of diel activity time, c hoosing in the evenings rock substrates, which held heat even after ai r temperature dropped. Reproductive condition (particularly gestation) of individuals also resulted in broadened diel activity periods. Ther mal relationships set upper distributional limits on egg-laying specie s, which cannot successfully reproduce at high elevations, where only live-bearing lizards were found.