Precision of Thermoregulation of Some African Lizards

Thermoregulatory abilities and patterns of thermoregulation were explored for 12 species of African lizards. They all regulated body temperature (Tb) by shuttling from sun to shade, and this movement resulted in a periodic fluctuation of Tb with time that showed intraspecific similarities and interspecific differences. A mean body temperature (T̄b) and amplitude and period of the Tb curve was calculated for each individual. In general, Tb was relatively independent of ambient temperature. Three attributes of thermoregulation were defined and used to characterize individuals and species. First, the relative precision of individuals was determined by examining both the standard deviation (SD) of the individual T̄b and the amplitude of the curve. Second, species were categorized according to the amount of variation among individuals based on the SD of the species T̄b. Third, the species each were described with regard to choice of high or low T̄b (ranging from thermophilic to thermophobic). The three attributes were then combined and used to compare simultaneously all 12 species. Most striking was the general lack of similarity among the species and the diversity of thermoregulatory modes.