Batesian

The mimic evolves to imitate the warning signals of a harmful species directed at a predator which they have in common. The model has some characteristic which makes it less profitable to a predator (such as unpalatability or poisonousness) and so mimics who express similar signals to the model are likely to be mistaken for the model and escape being preyed upon. When the mimic is less common than the model this arrangement can remain stable, since a predator is most likely to prey upon the model, be punished, and avoid similar prey in future. Where the mimic’s numbers are greater than the model’s, the probability of a young predator having a profitable first experience with a mimic is increased, damaging the effectiveness of the mimicry.

Mullerian

Similar to Batesian mimicry, but the model and mimic are both harmful to predators or not worthwhile as prey. At first, it was difficult to explain what catalyzed the mimicry, since a harmful species could seemingly rely on its own signalling to warn predators of its unpalatability. However, both model and mimic benefit from this arrangement since a predator is able to generalize a pattern of potentially harmful encounters more easily, strengthening the predator’s association between the signal and resulting harm by increasing the commonality of the signal. In this way, the predator also benefits.

Emsleyan/Mertensian

An unusual form of mimicry where deadly prey mimics a less dangerous, but still unprofitable species. In instances where a predator is likely to die as a result of an encounter with a particular prey they have no possibility of learning to avoid the prey, making unique signalling by the deadly prey pointless— it would be better off camouflaging to avoid attacks altogether. However, if a predator first learns to avoid a less deadly prey species by non-lethal encounters, it is likely also to avoid its mimics. Therefore, the deadlier species mimics the less deadly one to capitalize on the learned avoidance of that species by predators.

Vavilovian

A form of mimicry found in weeds which come to share characteristics with a domesticated plant through artificial selection. Selection against the weed may occur either by manually killing the weed, or by separating its seeds from those of the crop, pressuring the weed to express characteristics increasingly similar to the crop. Rye is an example of a ‘secondary crop’, originally a weed species which evolved to imitate wheat through artificial selection, until rye itself became worth harvesting. This form of mimicry does not occur in ecosystems unaltered by humans.

Concepts

• Commensalism: long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed
• Aposematism: use of warning coloration to inform potential predators that an animal is poisonous, venomous, or otherwise dangerous.
• Inquiline: an animal that lives commensally in the nest/ burrow/dwelling place of another species.
• Mutualism: ecological interaction between two or more species where each species has a net benefit.