Thermal biology of four Israeli agamid lizards in early summer

The agamid lizard genera Agama and Stellio differ in thermal biology during early summer in Israel. Species of Agama (A. pallida, A. savignii, and A. sinaita) are small, live in hot desert habitats, and frequently use thermoregulatory behaviors that foster convective cooling. Individuals in local populations maintain body temperatures within a narrow range (within and among species), and body temperatures are only slightly higher than air and substrate temperatures. In contrast, Stellio stellio is of moderately large size, occupies cooler habitats, and frequently uses behaviors which tend to increase rates of heat gain. Body temperatures for Stellio are lower than those of Agama, but are more elevated above environmental temperatures. In two Stellio populations at high altitudes, body temperatures were extremely variable. In the laboratory, A. savignii was more tolerant of high temperatures than any of four populations of Stellio, but tolerance of low temperatures did not vary among any of these five populations. Differences in thermal biology between the two genera may influence their geographical distribution in Israel.