Influences of season, time of day, light and sex on the thermoregulatory behaviour of crotaphytus collaris

Abstract

1. 1.|Temperature selection of male Crotaphytus collaris acclimatized to 25 ± 1° C and an LD 12:12 photoperiod was measured over a 24-h period in a thermal gradient with either a uniform light over the entire gradient (UL), a point source of light over the hot end of the gradient (LH), or a point source of light over the cold end of the gradient (LC) during spring, summer and fall. 2. 2.|Lizards placed in the LC condition showed abnormal temperature selection over time as compared to the UL and LH groups that selected higher photophase T b than scotophase T b . 3. 3.|Season had a significant effect on temperature selection. 4. 4.|Female lizards chose significantly higher T b than male lizards in the LH group during the summer. 5. 5.|The location of a point source of light has a major impact on thermoregulatory behaviour in the lizards distinct from the role played by a heat source.