Skin Coloration Changes and Thermoregulation in Anolis carolinensis Across Different Thermal Environments

Ambient temperature plays a crucial role in shaping the skin color of some lizard species. While the long-term correlation between ambient temperature and skin color changes in lizards has been well-studied, how they adjust skin color and body temperature in response to short-term thermal fluctuations remains unclear. In this study, we examined the impacts of ambient temperature on the body temperature and skin color of Anolis carolinensis. In a white background, as the ambient temperature rose from 20 °C to 40 °C, both body surface and core temperatures increased; skin brightness rose from 71.47 to 88.05 cd/m², chroma decreased from 43.55% to 36.43%, and hue dropped from 95.80° to 78.82°. Their changes against a brown background were similar to those against a white background. Correlation analysis showed that brightness was positively correlated with body temperature, chromaticity was negatively correlated with it, and hue negatively correlated with body temperature in white backgrounds but showed no significant correlation in brown backgrounds. As the ambient temperature rose from 20 °C to 40 °C, the spectral reflectance of skin in the visible (300-700 nm) and near-infrared (700-2500 nm) range increased from 26.01 ± 0.57% to 30.22 ± 0.63% and 8.61 ± 1.20% to 11.71 ± 1.48%, respectively. These results demonstrate that the skin color and spectral reflectance variations in A. carolinensis play a role in body temperature regulation. Additionally, this study offers new insights into the adaptive strategies of ectothermic organisms in balancing skin color and body temperature in fluctuating ambient temperatures.