Data from: The role of predators in maintaining the geographic organization of aposematic signals

Selective predation of aposematic signals is expected to promote phenotypic uniformity. But while uniform within a population, numerous species display impressive variations in warning signals among adjacent populations. Predators from different localities learning to avoid distinct signals while performing intense selection on others are thus expected to maintain such a geographic organization. We tested this assumption by placing clay frog models, representing distinct color morphs of the Peruvian poison-dart frog Ranitomeya imitator and a non conspicuous frog, reciprocally between adjacent localities. In each locality, avian predators were able to discriminate between warning signals; the adjacent exotic morph suffered up to four times more attacks than the local one and two times more than the non conspicuous phenotype. Moreover, predation attempts on the exotic morph quickly decreased to almost nil, suggesting rapid learning. This experiment offers direct evidence for the existence of different predator communities performing localized homogenizing selection on distinct aposematic signals.

针对警戒信号（aposematic signals）的选择性捕食，被认为可推动表型均一性（phenotypic uniformity）的形成。但尽管同一种群内部的表型均一，众多物种在相邻种群间却展现出显著的警戒信号差异。据此推测，来自不同地域的捕食者在学会规避特定信号的同时，对其他信号施加强烈选择压力，这正是维持此类地理分布格局的关键。为验证该假设，我们在相邻样地间交叉放置黏土蛙模型：这些模型分别代表秘鲁箭毒蛙（Ranitomeya imitator）的不同色型（color morphs），以及一种隐蔽型蛙类。在每个样地中，鸟类捕食者均可区分不同的警戒信号：相邻样地的外来色型所受攻击次数最多可达本地色型的4倍，是隐蔽型表型（non conspicuous phenotype）的2倍。此外，针对外来色型的捕食尝试迅速降至近乎为零，这表明捕食者具备快速学习能力。本实验为不同捕食者群落对不同警戒信号施加局域化同质化选择（localized homogenizing selection）提供了直接实证依据。