Welcome to the ScienceDuo blog by Chris Wallis and Rhiannon Morris. Screeds on science and sanity from two people who understand neither.
Bates and Muller are two of my scientific heroes and I love mimicry so I thought I would write a short post on Batesian and Mullerian mimicry!
In Batesian mimicry one species, called the mimic, gains in fitness by resembling another species, called the model. This model usually has an attribute that discourages predators, whereas the mimic does not. The mimic essentially imitates the harmful signs of the model species although the mimic itself is not harmful. The fitness benefit for a mimic depends on how closely it resembles the model and on the ratio of distasteful models to mimics. It is more beneficial for the mimic if there are more models than mimics. On the other hand, if there are more mimics than models, this becomes a disadvantage for both species as experiences with the mimic may lead to the model being seen as harmless by the predator. Some species have adapted to mimic multiple species, which would be of even higher fitness benefit to the mimic.
Plate from Bates illustrating Batesian mimicry between Dismorphia species (top row, third row) and various Ithomiini (Nymphalidae) (second row, bottom row). Henry Walter Bates 1862. Contributions to an insect fauna of the Amazon Valley. Lepidoptera: Heliconidae. Trans. Linn. Soc. 23: 495-566.
In Mullerian mimicry there are two distasteful model species which resemble one another. Fitness benefits come from greater numbers showing the same coloration that is distasteful to predators. This re-inforces the warning to predators, which learn not to prey on these species. In this kind of mimicry, the greater number of each model, the greater the fitness is for both.
Plates Showing Four Forms of H. numata, Two Forms of H. melpomene, and the Two Corresponding Mimicking Forms of H. erato. Repeating Patterns of Mimicry. Meyer A, PLoS Biology, Vol. 4/10/2006, e341
Although here I have focused on visual mimicry, it is important to note that mimicry can involve deceiving any of the senses of a predatory species.
Post by Rhee