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.据推测，针对警戒色信号（aposematic signals）的选择性捕食可推动种群表型的同质化。尽管同一种群内部的表型趋于统一，但诸多物种在相邻种群间的警戒色信号却呈现出显著差异。因此，若不同地域的捕食者学会规避特定信号，同时对其他信号施加强烈选择压力，便可维持这种地理分布格局。我们通过在相邻地域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）的不同色型与一种无显著警戒色的蛙类，以此验证该假设。在每个实验地域，鸟类捕食者均可区分不同的警戒色信号；外来的异地色型所遭受的攻击次数最多可达本地色型的4倍，是无警戒色表型的2倍。此外，针对外来色型的捕食尝试快速降至近乎为零，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色信号施加局域同质化选择压力的现象，提供了直接证据。