Aposematism

First, the selection of "red" as a releaser in courtship and social chasing indicates a secondarily evolved use of aposematic coloring. It is assumed here that aposematism in this and other red-and-black heliconiids, and their correlated development of Müllerian mimicry, occurred in evolution before the development of red as a social releaser.

The co-occurrence of conspicuous coloration and noxious characteristics in many coastal marine species suggests that aposematism is a common predator deterrent in the marine environment.

Detected prey can avoid an attack by way of warning signals (aposematism), for example, bright coloration as a sign of toxicity. […] Aposematisms offer opportunities for 'cheating' species which are not poisonous but show the same color pattern, so-called Batesian mimicry.

For example, both toxicity and coloration may be energetically costly to produce and maintain, and some theoretical models have predicted that once a predator has learned that a prey is toxic, prey should reduce the amount of energy invested in producing an honest signal. This could in turn make aposematism evolutionarily stable, as opposed to a constant arms race between toxicity, coloration and predator perception or toxic resistance

We focus in this text on animal defences, but aposematism may apply in other groups. Aposematism has thus been variously proposed in plants […] where, for example, conspicuous coloration on the tips of defensitve spines might serve to draw the attention of predators and deter them from attacking. It has been suggested also that aposematism exists in some fungi […]