page_title: Mimicry
section_title: Emsleyan/Mertensian
hierarchical_section_title: Mimicry / Classification / Defensive / Emsleyan/Mertensian
caption_attribution_description: English: Lampropeltis triangulum annulata. Animal courtesy of Austin Reptile Service.
context_page_description: In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. Often, mimicry functions to protect a species from predators, making it an antipredator adaptation. Mimicry evolves if a receiver perceives the similarity between a mimic and a model and as a result changes its behaviour in a way that provides a selective advantage to the mimic. The resemblances that evolve in mimicry can be visual, acoustic, chemical, tactile, or electric, or combinations of these sensory modalities. Mimicry may be to the advantage of both organisms that share a resemblance, in which case it is a form of mutualism; or mimicry can be to the detriment of one, making it parasitic or competitive. The evolutionary convergence between groups is driven by the selective action of a signal-receiver or dupe. Birds, for example, use sight to identify palatable insects, whilst avoiding the noxious ones. Over time, palatable insects may evolve to resemble noxious ones, making them mimics and the noxious ones models.
context_section_description: Emsleyan or Mertensian mimicry describes the unusual case where a deadly prey mimics a less dangerous species. It was first proposed by M. G. Emsley as a possible explanation for how a predator can learn to avoid a very dangerous aposematic animal, such as a coral snake, when the predator is very likely to die, making learning unlikely. The theory was developed by the German biologist Wolfgang Wickler who named it after the German herpetologist Robert Mertens.
  The scenario is unusual, as it is usually the most harmful species that is the model. But if a predator dies on its first encounter with a deadly snake, it has no occasion to learn to recognize the snake's warning signals. There would then be no advantage for an extremely deadly snake in being aposematic: any predator that attacked it would be killed before it could learn to avoid the deadly prey, so the snake would be better off being camouflaged, to avoid attacks altogether. But if the predator first learnt to avoid a less deadly snake that had warning colours, the deadly species could then profit (be attacked less often) by mimicking the less dangerous snake.
  Some harmless milk snake (Lampropeltis triangulum) subspecies, the moderately toxic false coral snakes (genus Erythrolamprus), and the deadly coral snakes (genus Micrurus) all have a red background color with black and white / yellow rings. In this system, both the milk snakes and the deadly coral snakes are mimics, whereas the false coral snakes are the model.
caption: The harmless Mexican milk snake, Lampropeltis triangulum annulata (the Batesian mimic)
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