Evolutionarily stable investment in anti-predatory defences and aposematic signalling

Abstract

Many species possess defences (such as toxins) against predator attack which cannot be observed by the predator prior to attack, but which it might be beneficial for the predator to avoid. Often, such animals are brightly coloured or have some other way of signalling that they are defended (aposematism). In one of our papers we examined the evolution and maintenance of defence and conspicuousness, the brightness of the defence signal, in such prey species using a game theoretic model. In this chapter we develop the model further and in particular expand on the more theoretical results with examples demonstrating the type of solutions which can occur. We categorise eight possible configurations of solution states for simple solutions. Finally there is another class of solutions possible where there is strong between-individual variation in appearance between conspicuous, poorly defended prey, and we demonstrate one example of this complex solution.