Behavioral thermoregulation is highly repeatable and unaffected by digestive status in Agama atra

The precision and the extent of behavioral thermoregulation are likely to provide fitness benefits to ectotherms. Yet the factors driving variation in selected or preferred body temperature (T_set ) and its usefulness as a proxy for optimal physiological temperature (T_opt ) are still debated. Although T_set is often conserved among closely related species, substantial variation at the individual, population and species level has also been reported. However, the repeatability (calculated as the intra-class correlation coefficient) of T_set is generally low. One factor that influences T_set is feeding status, with fed reptiles typically showing higher T_set , a process thought to aid meal digestion. Here, using experiments simulating realistic feeding and fasting regimes in Agama atra, a heliothermic lizard from southern Africa, we test if T_set and its repeatability under these 2 states significantly differ. Daily T_set ranged from 33.7 to 38.4 °C, with a mean (± SE) of 36.7 ± 0.1 °C for fed and 36.6 ± 0.1 °C for unfed individuals. Comparisons of repeatability showed that females tend to be more consistent in the selection of body temperature than males, but not significantly so regardless of feeding status. We report some of the highest repeatability estimates of T_set to date (full range: 0.229-0.642), and that the weak positive effects of feeding status on T_set did not increase its repeatability. In conclusion, one of the major prerequisites for natural selection, consistent among-individual variation, is present, making the adaptive significance of T_set considerably more plausible.