Data from: Colour change on different body regions provides thermal and signalling advantages in bearded dragon lizards

Many terrestrial ectotherms are capable of rapid colour change, yet it is unclear how these animals accommodate the multiple functions of colour, particularly camouflage, communication and thermoregulation, especially when functions require very different colours. Thermal benefits of colour change depend on an animal's absorptance of solar energy in both UV–visible (300–700 nm) and near-infrared (NIR; 700–2600 nm) wavelengths, yet colour research has focused almost exclusively on the former. Here, we show that wild-caught bearded dragon lizards (Pogona vitticeps) exhibit substantial UV–visible and NIR skin reflectance change in response to temperature for dorsal but not ventral (throat and upper chest) body regions. By contrast, lizards showed the greatest temperature-independent colour change on the beard and upper chest during social interactions and as a result of circadian colour change. Biophysical simulations of heat transfer predicted that the maximum temperature-dependent change in dorsal reflectivity could reduce the time taken to reach active body temperature by an average of 22 min per active day, saving 85 h of basking time throughout the activity season. Our results confirm that colour change may serve a thermoregulatory function, and competing thermoregulation and signalling requirements may be met by partitioning colour change to different body regions in different circumstances.

许多陆生变温动物均可实现快速体色变化，但目前尚不明确这类动物如何兼顾体色的多重功能——尤其是伪装、信号交流与体温调节，尤其当不同功能所需体色差异极大时。体色变化的体温调节效益取决于动物对紫外可见光（UV–visible，300~700 nm）与近红外（NIR，700~2600 nm）波段太阳能的吸收率，但当前体色研究几乎仅聚焦于前者。本研究显示，野生捕获的鬃狮蜥（Pogona vitticeps）的背部皮肤可随温度变化发生显著的紫外可见光与近红外波段反射率改变，而腹面（喉部与上胸部）区域无此现象。与之形成对比的是，鬃狮蜥在社交互动期间以及因昼夜节律性体色变化时，其鬃毛区域与上胸部的体色变化受温度影响最小、变化幅度最大。热传递生物物理模拟预测，背部反射率的最大温度依赖性变化可使每活动日达到活跃体温的时间平均缩短22分钟，整个活动季累计可节省85小时的晒背时间。本研究结果证实，体色变化可兼具体温调节功能；通过在不同情境下将体色变化分配至不同身体区域，可兼顾相互冲突的体温调节与信号交流需求。