Evolutionary Rates of Models and Mimics in Batesian Mimicry

Abstract

As was first pointed out by R. A. Fisher, the evolution of close Batesian mimicry requires that the mimic evolve faster toward its model than the model away from it. There are three main reasons why in most cases the mimic should be able to evolve faster than the model: (1) When mimicry is not perfect the mimic is expected to suffer higher mortality (per individual) from the predators affected by mimicry than the model. (2) In the mimic the amount of genetic variability available for further evolution should be greater than in the model. (3) While in the mimic any change in the phenotype toward the model should be advantageous, in the model, changes away from the mimic should sometimes be disadvantageous because they would result in a phenotype which the predators may not recognize as distasteful.