Résumé
The persistence of distinct warning signals within and between sympatric
mimetic communities is a puzzling evolutionary question because selection
favours convergence of colour patterns among toxic species. Such
convergence is partly shaped by predators’ reaction to similar but not
identical stimulus, i.e. generalization behaviour. And generalisation by
predators is likely to be shaped by the diversity of local prey.
However, studying generalization behaviour is generally limited
to simple variations of prey colour patterns. Here, we used a computer
game played by humans as surrogate predators to investigate generalization
behaviours on simple (4 morphs) and complex (10 morphs) communities of
unprofitable (associated with a penalty) and profitable butterflies.
Colour patterns used in the game are observed in the natural populations
of unprofitable butterfly species such as Heliconius numata. Analyses of
449 game participants’ behaviours show that players avoided unprofitable
prey more readily in simple than in complex communities. However,
generalization was observed only in players that faced complex
communities, enhancing the protection of profitable prey that looked
similar to at least one unprofitable morph. Additionally, similarity among
unprofitable prey also reduced attack rates only in complex communities.
These results are consistent with previous studies using avian predators
but artificial colour patterns and suggest that mimicry is more likely to
evolve in complex communities where increases in similarity are more
likely to be advantageous.