A lizard basking on a sun-warmed rock changes its location and posture to control heat exchange, an example of behavioural thermoregulation. Solar radiation and conduction from the rock raise body temperature, increasing enzyme activity, nerve conduction, muscle performance, digestion, and escape speed toward an optimal range. Once sufficiently warm, the lizard may move into shade, flatten or elevate its body, orient differently to the sun, or retreat into a burrow to avoid overheating. Most lizards are ectothermic: environmental sources provide the majority of their heat. This differs from en
Ref:
Evolutionary Analysis, Herron & Freeman, 5th Ed., Ch. 10