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 hours 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.诸多陆生变温动物具备快速体色变化的能力，但目前尚不清楚这类动物如何协调体色的多重功能——尤其是伪装、通讯与体温调节，尤其当不同功能所需的体色差异极大时。体色变化的体温调节收益，取决于动物对紫外可见光（UV-visible，300–700 nm）与近红外（NIR，700–2600 nm）波段太阳能的吸收效率，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）的背部区域可随温度变化发生显著的紫外可见光与近红外皮肤反射率改变，而腹部区域（喉部与上胸部）则无此现象。与之相反，鬃狮蜥在社交互动过程中以及因昼夜节律发生体色变化时，其喉部与上胸部区域会出现最为显著的、不受温度影响的体色改变。热传递生物物理模拟结果表明，背部反射率最大的温度依赖性变化，可使动物达到活动体温所需的时间平均每日减少22分钟，在整个活动季累计可节省85小时的晒太阳时长。本研究结果证实，体色变化可发挥体温调节功能，而通过在不同情境下将体色变化分配至不同身体区域，可协调体温调节与信号传递之间的竞争性需求。