Ontogenetic differences in the preferred body temperature of the European adder Vipera berus

Abstract

We tested the hypothesis that the costs of thermoregulation (e.g. predation) can affect the preferred body temperature (Tp, the "target" body temperature in thermoregulation) of reptiles. In European adders (Vipera berus), juveniles face higher predation risks than adults. We compared Tp between adult and juvenile adders and found that the Tp of juveniles was approximately 5°C lower than that of adults, while adult males and females did not differ. All groups were characterized by narrow Tp ranges. Our results suggest that reptiles may change their Tp in response to the high ecological costs of thermoregulation. Alternative explanations for the reported pattern are also discussed.