Relative importance of taste and visual appearance for predator education in Mullerian mimicry

Mullerian mimicry, by definition, is the visual resemblance between two or more aposematic prey species. According to classical Mullerian mimicry theory, comimics draw mutual benefits from the resemblance because predators have to learn to avoid only one colour pattern. In contrast, the relatively untested quasi-Batesian mimicry theory suggests that, because of differences in unpalatablility, the less toxic mimic acts like a parasite on the more defended prey, decreasing its fitness. We tested predation pressures on artificial mimicry complexes in which comimics varied both in visual similarity and in taste. Both signal and taste were important for the survival of comimics. Predators learned to avoid two similarly conspicuous comimics differently when they were presented alone, suggesting that the signals were unequal. Despite the discrepancy in signal, imperfect visual mimicry did not increase the total number of comimics eaten, as suggested by the classical theory. Great tits, Parus major, learned to avoid highly unpalatable prey faster than mildly unpalatable prey. However, variation in palatability did not unequivocally increase the total mortality of models; instead, the effects depended on the signal of the prey. These results indicate that Mullerian mimicry dynamics may change depending on the configuration of mimicry complexes. (c) 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.