Thus they could respond only to the taste of the butterfly. In one fell swoop the basis for supporting Batesian mimicry between these species disappeared. Not all is lost, however. A few years after Bates a German zoologist, Fritz Muller also went collecting butterflies on the Amazon. Once bitten, twice shy,' presupposes at least one bite.
Predators have only to learn one pattern and fewer butterflies get eaten.
This reciprocal kind of mimicry is called Mullerian and it seems that the relation between Monarchs and Viceroys may be an example of it. In fact the evolutionary and ecological dynamics of these two types of mimicry are very different in terms of both predators and prey. Mullerian mimics, for example, should be converging over time on a common aposematic pattern whereas Batesian models should experience a pressure to diverge from their mimics. Moreover, other research is undermining the underpinings of mimicry. It is now thought that butterflies often evolve their own chemical defenses and only afterwards shift their feeding preferences to plants protected by similar means.