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.Abstract
The effect of environmental temperature on (A) the temperature of the female's body, clutch, and nest, and (B) temperature differentials between these three temperatures and the environmental temperature in female Burmese Pythons (Python bivittatus, N = 3). Dashed lines represent the predicted result if optimal temperature of 33°C had been maintained while the dotted line represents temperature without thermogenesis. Asterisks indicate statistically significant effects of environmental temperature using rmANOVA. Values are presented as mean ± SE.
The effect of environmental temperature on twitch rate (Rtw) in brooding female Burmese Pythons (N = 3). Letters indicate statistical differences among temperatures using rmANOVA. Values are presented as mean ± SE.
The effect of environmental temperature on mean metabolic rate (
) of two female Burmese Pythons (Python bivittatus) during brooding and after reproduction.
Metabolic rate (
), female body temperature (Tb), and twitch rate (Rtw) over a 24-h period for two brooding female Burmese Pythons (Python bivittatus) at three environmental temperatures. Upper graphs (A, B) show metabolic rate and lower graphs (C, D) show body temperature and twitch rate on a split x-axis. Data were collected simultaneously for each female. ANOVA analysis revealed no statistical differences among hours. Values for Rtw were calculated for each hour and are presented as mean ± SE.
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