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

## TL;DR

This study shows how the green anole lizard changes its skin color and reflectance to regulate body temperature in response to different ambient temperatures.

## Contribution

The study reveals a novel thermoregulatory role of skin color changes in Anolis carolinensis under short-term temperature fluctuations.

## Key findings

- Skin brightness increased and chroma decreased as ambient temperature rose from 20 °C to 40 °C.
- Skin spectral reflectance in visible and near-infrared ranges increased with higher temperatures.
- Optimal body temperature was observed around 30 °C, where body temperature matched ambient temperature.

## Abstract

Ambient temperature affects the skin color of some lizard species, but it was previously unclear how lizards adjust their skin color and body temperature in response to short-term temperature fluctuations. This study focused on the Anolis carolinensis to explore the impacts of different ambient temperatures on its skin color, body temperature, and skin spectral reflectance. The results showed that when the temperature rose from 20 °C to 40 °C, the lizard’s skin became brighter, color intensity decreased, and the reflectance of visible and near-infrared light increased. Around 30 °C was its optimal temperature, where body temperature was closest to ambient temperature. The study demonstrated that this lizard’s skin color changes not only serve camouflage and signal transmission but also help regulate body temperature. This provides a new perspective for understanding how ectothermic organisms adapt to ambient temperature fluctuations and has reference value for ecological conservation and biological adaptation research.

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.