Mimicry means that one species of animal resembles another species closely enough to deceive predators. To evolve, the mimicked species must have warning coloration, because appearing to be bitter-tasting or dangerous gives natural selection something to work on. Once a species has a slight, chance, resemblance to a warning coloured species, natural selection can drive its colours and patterns towards more perfect mimicry. There are numerous possible mechanisms, of which by far the best known are: Batesian mimicry, where an edible species resembles a distasteful or dangerous species. This is most common in insects such as butterflies. A familiar example is the resemblance of harmless hoverflies (which have no sting) to bees. Mullerian mimicry, where two or more distasteful or dangerous animal species mutually resemblance each other. This is most common among insects such as wasps and bees (hymenoptera). Batesian mimicry was first described by pioneering naturalist Henry W. Bates. When an edible prey animal comes to resemble, even slightly, a distasteful animal, natural selection favours those individuals that even very slightly better resemble the target. This is because even a small degree of protection reduces predation and increases the chance that an individual mimic will survive and reproduce. For example, many species of hoverfly are coloured black and yellow like bees, and are in consequence avoided by birds (and people). Mullerian mimicry was first described by pioneering naturalist Fritz Muller. When a distasteful animal comes to resemble a more common distasteful animal, natural selection favours individuals that even very slightly better resemble the target. For example, many species of stinging wasp and bee are similarly coloured black and yellow. Muller's explanation of the mechanism for this was one of the first uses of mathematics in biology. He argued that a predator, such as a young bird, must attack at least one insect, say a wasp, to learn that the black and yellow colours mean a stinging insect. If bees were differently coloured, the young bird would have to attack one of them also. But when bees and wasps resemble each other, the young bird need only attack one from the whole group to learn to avoid all of them. So, fewer bees are attacked if they mimic wasps; the same applies to wasps that mimic bees. The result is mutual resemblance for mutual protection.
Mullerian mimicry is a natural phenomenon in which two or more poisonous species, that may or may not be closely related and share one or more common predators, have come to mimic each other's warning signals. It is named after the German naturalist Fritz Muller, who first proposed the concept in 1878. The phenomenon can be understood by imagining two poisonous species that do not resemble one another and are also prey to a common predator. Occasionally, individuals of the predatory third species will encounter one or the other type of noxious prey, and thereafter avoid it. Predators that avoid only one or the other type of harmful species provide no benefit to the species that is not avoided. Therefore, there is an evolutionary advantage to be gained in the gradual approach in appearance of the two prey species. This is because a predator that learns to avoid either species in a pair of species exhibiting Mullerian mimicry learns, in effect, to avoid both. This strategy is typically contrasted with Batesian mimicry, in which one harmless species adopts the appearance of another, harmful species to gain the advantage of predators' avoidance. However, because comimics may have differing degrees of protection, the distinction between Mullerian and Batesian mimicry is not absolute, and there can be said to be a spectrum between the two forms. Additionally, a species may be a Batesian mimic to one predator and a Mullerian mimic to another. While Batesian and Mullerian mimicry are commonly given examples of mimicry, there is often little or no mention of other forms. There are many other types of mimicry however, some very similar in principle, others far separated. For example in aggressive mimicry a predator might mimic the food of its prey, luring them towards it and improving its foraging success. Mullerian mimicry needs not involve visual mimicry; it may employ any of the senses. For example, many snakes share the same auditory warning signals, forming an auditory Mullerian mimicry ring. More than one common signal may show convergences by the parties. While model and mimic are often closely related species, Mullerian mimicry between very distantly related taxa also occurs.