Thermal Dependence of Appetite and Digestive Rate in the Flat Lizard, Platysaurus intermedius wilhelmi

Abstract

We investigated the thermal dependence of appetite and digestive rate in the flat lizard, Platysaurus intermedius wilhelmi, over a wide thermal range (12?-34?C). Because Platysaurus seldom venture off rock outcrops, their body temperatures are determined to a large extent by the thermal characteristics of this microhabitat. Our results demonstrate that appetite, measured as the number of food items eaten in a given time, is clearly temperature-dependent, increasing to a maximum that coincides with the thermal preference of 32?C for the species. Our measures for digestive rate, measured as the time to the first passing of feces after a meal, are temperature-dependent below 22?C but are temperature-independent between 22? and 34?C. Furthermore, our data indicate a critical body temperature of 12?C, below which all feeding ceases. We predict that lizards of this species with TbS below 20?C are effectively excluded from nutritive energy gain under natural conditions.