Etude comparative de la résistance à la chaleur d’Uromastix acanthinurus et de Varanus griseus

Abstract

Field experiments have been conducted in the Algerian Sahara to test the ability of two lizards of about the same size Uro-mastix acanthinurus and Varanus griseus, to regulate their body temperature when exposed to sun in conditions preventing any behavioral regulation. Both species are able, through increased ventilation, to prevent a too rapid increase of body temperature, but physiological regulation is more efficient in Varanus than in Uromastix. The Sand monitor is able, even in the hottest part of the day, to keep its body temperature at a more or less constant level (42° C) for up to 4 hours, in contrast with Uromastix which is not able to do this. Young Uromastix are able to resist heat stress much better than adults.