Abstract

In squamate reptiles the effects of pregnancy on physiological thermoregulation, such as thermal tolerances and rates of heat exchange, are practically unknown. This is remarkable since pregnancy involves changes in body vascularization and may consequently affect heat exchange. We studied the effects of pregnancy on physiological thermoregulation in four oviparous Liolaemus species from central Chile. Results indicated that pregnancy did not affect most of the variables measured. In two species, however, pregnant females had slower heating rates than non-pregnant individuals, suggesting a capacity to control the egg thermal environment. On the other hand, in contrast to other small lizards, in Liolaemus heating, but not cooling, rates may have an adaptive value as a thermoregulatory mechanism. Cooling rates and thermal minimal tolerances seem to evolve less readily.