Predator learning favours mimicry of a less-toxic model in poison frogs

Don't eat me One of the earliest tests of Darwin's theory of natural selection was defensive mimicry, and this act of deception continues to cast light into hidden corners of evolutionary biology. Few frogs catch the eye like poison frogs — and such is their intent. Their garish colours advertise toxicity, and ‘cheating’ species mimic the warning coloration without the toxins to back it up. A study in the Amazonian rainforest in Ecuador has produced the surprising finding that edible frogs mimic the less toxic of two poison-frogs in the vicinity. Why mimic the less potent deterrent? The answer, discovered through learning experiments, lies in avoidance psychology. Extreme noxiousness makes predators avoid things that only slightly resemble the noxious object; however, with less severity, predator avoidance becomes specific. So the mimics of the less toxic poison frog gain total protection; they are avoided by predators learning on either the more or less toxic frogs.