Data from: Poison frog colors are honest signals of toxicity, particularly for bird predators

Antipredator defenses and warning signals typically evolve in concert. However, the extensive variation across taxa in both these components of predator deterrence, and the relationship between them, are poorly understood. Here we test whether there is a predictive relationship between visual conspicuousness and toxicity levels across 10 populations of the color polymorphic strawberry poison frog, Dendrobates pumilio. Using a mouse-based toxicity assay, we find extreme variation in toxicity between frog populations. This variation is significantly positively correlated with frog coloration brightness, a viewer-independent measure of visual conspicuousness (i.e. total reflectance flux). We also examine conspicuousness from the view of three potential predator taxa, as well as conspecific frogs, using taxon-specific visual detection models and three natural background substrates. We find very strong positive relationships between frog toxicity and conspicuousness for bird-specific perceptual models. Weaker but still positive correlations are found for crab and D. pumilio conspecific visual perception, while frog coloration as viewed by snakes is not related to toxicity. These results suggest that poison frog colors can be honest signals of prey unpalatability to predators, and that birds in particular may exert selection on aposematic signal design.

反捕食防御与警戒信号通常协同演化。然而，学界对捕食者威慑效应的两类组成要素（反捕食防御与警戒信号）在不同类群间的广泛变异，以及二者之间的关联，仍缺乏深入了解。本研究针对体色多态的草莓箭毒蛙（Dendrobates pumilio）的10个种群，检验视觉显著性（visual conspicuousness）与毒性水平之间是否存在预测性关系。本研究采用基于小鼠的毒性检测实验，发现不同蛙种群间的毒性存在极大的变异。该毒性变异与蛙类体色亮度呈显著正相关，而体色亮度是一种不依赖于观察者的视觉显著性度量（即总反射通量（total reflectance flux））。本研究还借助类群特异性视觉检测模型与三种天然背景基质，分别从三种潜在捕食者类群以及同种蛙类的视角评估了视觉显著性。针对鸟类特异性感知模型的分析结果显示，蛙类毒性与视觉显著性之间存在极强的正相关关系；对于蟹类以及草莓箭毒蛙同种个体的视觉感知，虽相关性较弱但仍呈显著正相关；而以蛇类视角观测的蛙类体色，则与毒性并无关联。上述结果表明，箭毒蛙的体色可作为向捕食者传递猎物不可口性的诚实信号（honest signals），而鸟类尤其可能对警戒信号的设计施加选择压力。