Evolutionary and Ecological Physiology

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Thermoregulation

selected references

Behavioural thermoregulation is an impotant aspect in the thermal biology of endotherms and ectotherms. By altering behavioural posture or moving between thermally different microhabitats, animals modify the operative temperature they experience and thereby alter heat transfer rates with the environment.

Transient receptor potential ion channels (TRPV1 and TRPM8) are the mechanism by which reptiles sense their environment. The TRP genes are expressed throughout the body and permit the animals to contrast environmental and internal temperatures to initiate thermoregulatory behaviour.

To determine whether or not behavioural sequences represent thermoregulation requires comparison between the study animal and a control. Random distributions of body temperature of a hypothetical animal are often used as a control, and these distributions may be derived from physical models, or from calculations of transient heat transfer.

Fig. 1 Body temperature measurements of an alligator in Louisiana in summer (red line), and the corresponding operative temperature (light blue line), and the predicted body temperature of the same animal if it was behaving randomly (dark blue line).

References

Seebacher, F., and Murray, S. A. 2007. Transient receptor potential ion channels control thermoregulatory behaviour in reptiles. PLoS One 3, e281.

Seebacher, F., and Shine, R. 2004. Evaluating thermoregulation in reptiles: the fallacy of the inappropriately applied method. Physiological and Biochemical Zoology 77, 688-695.

Seebacher, F., Elsey, R. M. and Trosclair, P. L. III. 2003. Body temperature null-distributions in large reptiles: seasonal thermoregulation in the American alligator (Alligator mississippiensis). Physiological and Biochemical Zoology 76, 348-359.

Seebacher, F. 2003. Dinosaur body temperatures: the occurrence of endothermy and ectothermy. Paleobiology 29, 105-122.

Seebacher, F. 1999. Behavioural postures and the rate of body temperature change in wild freshwater crocodiles, Crocodylus johnstoni. Physiological and Biochemical Zoology 72, 57-63.