Data from: Orientation to the sun by animals and its interaction with crypsis

1. Orientation with respect to the sun has been observed in a wide range of species and has generally been interpreted in terms of thermoregulation and/or ultraviolet (UV) protection. For countershaded animals, orientation with respect to the sun may also result from the pressure to exploit the gradient of coloration optimally to enhance crypsis. 2. Here, we use computational modelling to predict the optimal countershading pattern for an oriented body. We assess how camouflage performance declines as orientation varies using a computational model that incorporates realistic lighting environments. 3. Once an optimal countershading pattern for crypsis has been chosen, we determine separately how UV protection/irradiation and solar thermal inflow fluctuate with orientation. 4. We show that body orientations that could optimally use countershading to enhance crypsis are very similar to those that allow optimal solar heat inflow and UV protection. 5. Our findings suggest that crypsis has been overlooked as a selective pressure on orientation and that new experiments should be designed to tease apart the respective roles of these different selective pressures. We propose potential experiments that could achieve this.1. 众多物种类群均存在相对于太阳的朝向行为，此类行为通常被归因于体温调节和/或紫外线（UV）防护需求。对于具有反荫蔽（countershading）体色的动物而言，其太阳朝向行为也可能源于通过最优利用体色梯度以强化隐蔽性（crypsis）的进化压力。2. 本研究通过计算建模，预测具有固定朝向的动物躯体的最优反荫蔽体色模式；并借助纳入真实光照环境的计算模型，量化分析朝向变化时隐蔽效能的衰减幅度。3. 在确定用于强化隐蔽性的最优反荫蔽体色模式后，我们分别分析了紫外线防护/辐照量与太阳热摄入随朝向变化的波动规律。4. 研究结果表明，可通过反荫蔽体色最优强化隐蔽性的躯体朝向，与实现最优太阳热摄入及紫外线防护的朝向高度吻合。5. 本研究结果显示，隐蔽性作为朝向行为的选择压力这一作用长期被忽视，未来应设计新实验以厘清上述不同选择压力的各自贡献；本文同时提出了可实现该目标的潜在实验方案。