Revisiting Python Thermogenesis: Brooding Burmese Pythons (Python bivittatus) Cue on Body, not Clutch, Temperature

Previous studies have shown that brooding Burmese Pythons, Python bivittatus, use endogenous heat production to buffer clutch temperature against suboptimal environmental temperatures and that heat production is correlated with body muscle twitch rate and metabolic rate. Improving our understanding of the patterns of thermogenesis and the mechanisms that regulate it will provide insight into the proposed link between parental care and the evolution of endothermy. We measured body, clutch, and nest temperatures and also muscle twitch rate and metabolic rate to evaluate the buffering capability of thermogenesis during brooding as well as the thermal cues regulating thermogenesis. We found that, as expected, both muscle twitch rate and metabolic rate were correlated negatively with nest temperature. Furthermore, at nest temperature 6 degrees below optimal developmental temperature, females maintained body temperature at the optimal temperature. However, while thermogenesis increased clutch temperature significantly, clutch temperature decreases with decreasing nest temperature. Our results confirm general patterns of facultative thermogenesis reported previously and, in addition, strongly suggest that females use core body temperature to regulate their thermogenic activity.