Data and R code for the manuscript "Hidden colour signals as key drivers in the evolution of anti-predator coloration and defensive behaviours in snakes"

The initial evolution of warning coloration (“aposematism”) within a cryptic population of defended prey presents an evolutionary paradox. Recent findings suggest that prey which combine cryptic colours with conspicuous patches on concealed body parts (“hidden signallers”), may have mediated the transition of species from camouflage to aposematism. Here, we examine the patterns of anti-predator colour evolution and test whether species with hidden colours serve as an intermediate stage in the evolution of aposematism, focusing on the colour-diverse snake family Elapidae. Phylogenetic comparative analysis revealed key patterns in anti-predator colour evolution: (i) a few major transitions influenced the overall distribution of anti-predator coloration, and (ii) aposematism evolved multiple times, with hidden coloration as a major precursory state. We also quantified associations between colour patterns and defensive behaviours that reveal ventral surfaces (i.e. hidden signals). We found that venter-revealing defensive behaviours are frequently associated with hidden colour signals, and that the evolution of these behaviours and hidden colours are associated. Our results highlight the importance of hidden colours in evolutionary transitions to aposematism and the co-evolution of defensive behaviour with anti-predator coloration in snakes.

具有防御机制的隐蔽种群（cryptic population）内，警戒色（aposematism）的初始演化曾是一道经典进化悖论。近期研究指出，同时携带隐蔽色（cryptic colours）与隐蔽躯体部位显眼斑块（conspicuous patches）的猎物，即“隐蔽信号者（hidden signallers）”，或可介导物种从伪装向警戒色的演化过渡。本研究聚焦色彩多样性丰富的眼镜蛇科（Elapidae）类群，旨在考察反捕食色彩演化的整体模式，并检验隐蔽色彩物种是否可作为警戒色演化的中间过渡阶段。系统发育比较分析（phylogenetic comparative analysis）揭示了反捕食色彩演化的两项关键模式：其一，少数重大演化事件塑造了反捕食色彩的整体分布格局；其二，警戒色曾多次独立演化，且隐蔽色彩是其主要的前体演化状态。我们还量化了色彩模式与显露腹面（ventral surfaces，即隐蔽信号）的防御行为之间的关联。研究结果显示，显露腹面的防御行为常与隐蔽色彩信号存在显著关联，且这类防御行为与隐蔽色彩的演化过程存在协同关系。本研究成果凸显了隐蔽色彩在物种向警戒色的演化过渡中所发挥的关键作用，以及蛇类防御行为与反捕食色彩的协同演化机制。