A Comparative Study of Preferred Body Temperatures and Critical Thermal Tolerance Limits among Populations of Zootoca vivipara (Squamata: Lacertidae) along an Altitudinal Gradient

Abstract

We compared preferred body temperatures, critical thermal minima, and maxima, and toler- ance ranges among four populations of Zootoca vivipara (formerly Lacerta vivipara) distributed along an altitudinal gradient (250-1450 m) to examine whether different thermal environments have induced a change in these thermal characteristics. Lizards in all populations had similar preferred body temperatures and critical thermal limits, suggesting that acclimation or adaptation of these traits to different thermal environ- ments did not occur. Subadult females and gravid females preferred lower body temperatures than non- gravid females and subadult and adult males. Preferred body temperatures differed among individuals of the same age and sex within a particular population. In contrast to the negligible among-population vari- ation, preferred body temperatures varied considerably within populations in Z. vivipara.