Light versus Heat: Thermoregulatory Behavior in a Nocturnal Lizard (Gekko gecko)

• Published in: Herpetologica Vol. 44; no. 3; pp. 266 - 273
• Main Authors: Sievert, Lynnette M., Hutchison, Victor H.
• Format: Journal Article
• Language: English
• Published: Johnson, TN Herpetologists' League 01-09-1988
• Subjects: Acclimatization; Biological and medical sciences; Body temperature; Fundamental and applied biological sciences. Psychology; Herpetology; Lighting; Lizards; Photophase; Scotophase; Statistical variance; Temperature gradients; Thermoregulation; Thermoregulation. Hibernation. Estivation. Ecophysiology and environmental effects; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrata; Gekko gecko; Gradient; Temperature; Sauria; Thermoregulation; Reptilia; Photoperiod; Biological rhythm; Nocturnal animal; Circadian rhythm; Metabolism
• ISSN: 0018-0831; 1938-5099

Tokay geckos (Gekko gecko) acclimatized to 25 ± 1 C and a LD 12:12 photoperiod exhibited significant diel cycles of temperature selection in a thermal gradient with either uniform light over the entire gradient (UL) or a point-source of light over the hot end of the gradient (LH). Both groups selected higher body temperatures at night than during the day. No diel cycle was observed in the geckos exposed to the paradoxical condition of a point-source of light over the cold end of the gradient (LC). The UL and LH groups showed greater precision in thermoregulation during the scotophase than during the photophase. The opposite was found for the LC group. We concluded that light has a definite impact on thermoregulatory behavior that is distinct from the role that heat plays in thermoregulation. We recommend that variance be used as a standardized measure of thermoregulatory precision.