Question

Explain why coevolution through Batesian mimicry is most likely to be stable when the mimic species is rarer than the model species?

Answer 1

Coevolution through Batesian mimicry is most likely to be stable when the mimic species is rarer than the model species. This is because:

Batesian mimics should lose protection when common: they hide among superficially similar models, and hence are better off rare.

Rare mimetic morphs should be fittest because of this diversifying frequency-dependent selection, leading to the possibility of stable polymorphism if several distinct models are imitated by a single species.

One of the main attributes of Batesian mimicry is that the mimic is deleterious to its model.

The model could therefore escape its mimic by evolving a new warning pattern. However, this escape is likely to be transient, because mutant models could soon attract new mimics: a coevolutionary chase may result between models and mimics, an evolutionary ‘arms race’ similar to that in host-parasite interactions

More recently, equations for coevolution of a pair of mimetic species have been developed, which show that cyclical coevolution of model and mimic are possible if interspecific interactions (i.e. benefit of mimicry to the mimic and cost of Batesian mimicry to the model) are stronger than intraspecific interactions (i.e. aposematism and palatability).