Mimicry

A Batesian mimic, such as a hoverfly, is harmless, while its model, such as a wasp, is harmful, and is avoided by the dupe, such as an insect-eating bird.

More complex types may be bipolar, involving only two species, such as when the model and the dupe are the same; this occurs for example in aggressive mimicry, where a predator in wolf-in-sheep's-clothing style resembles its prey, allowing it to hunt undetected.

Returning home, he described multiple forms of mimicry in an 1862 paper at the Linnean Society in London,[6] and then in his 1863 book The Naturalist on the River Amazons.

[2][7] The term "Batesian mimicry" has since been used in his honour, its usage becoming restricted to the situation in which a harmless mimic gains protection from its predators by resembling a distasteful model.

[2] Among the observations in Bates's 1862 paper is the statement: I was never able to distinguish the Leptalides from the species they imitated, although they belong to a family totally different in structure and metamorphosis from the Heliconidae, without examining them closely after capture.

He first published a journal article on mimicry in German in 1878,[8] followed in 1879 by a paper to the Entomological Society of London (translated and presented by Ralph Meldola).

[9] He described a situation where different species were each unpalatable to predators, and shared similar, genuine, warning signals.

[5][10] Müller wrote that The resemblance of the genera named [Ituna and Thyridia] is the more worthy of notice since it occurs between insects both belonging to the group of butterflies which are protected by distastefulness.

[26][27][28] Convergent evolution is an alternative explanation for why coral reef fish have come to resemble each other;[29][30] the same applies to benthic marine invertebrates such as sponges and nudibranchs.

The terminology used has been debated, as classifications have differed or overlapped; attempts to clarify definitions have led to the partial replacement of old terms with new ones.

In Batesian mimicry, the mimic resembles the model, but does not have the attribute that makes it unprofitable to predators (e.g., unpalatability, or the ability to sting).

[52] In Müllerian mimicry, two or more species have similar warning or aposematic signals and both share genuine anti-predation attributes (e.g. being unpalatable), as first described in Heliconius butterflies.

The signal receiver also benefits by this system, despite being deceived about species identity, as it is able to generalize the pattern to potentially harmful encounters.

When both are present in similar numbers, however, it makes more sense to speak of each as a co-mimic than of distinct 'mimic' and 'model' species, as their warning signals tend to converge.

[43] Also, the mimetic species may exist on a continuum from harmless to highly noxious, so Batesian mimicry grades smoothly into Müllerian convergence.

Emsleyan or Mertensian mimicry describes the unusual case where a deadly prey mimics a less dangerous species.

It was coined by Pasteur as a phrase for such rare mimicry systems,[2] and is named after the American ecologist Lawrence E. Gilbert who described it in 1975.

[62] The classical instance of Gilbertian mimicry is in the plant genus Passiflora, which is grazed by the micropredator larvae of some Heliconius butterflies.

Examples include the monarch and the queen from the subfamily Danainae, which feed on milkweed species of varying toxicity.

Some insects such as some lycaenid butterflies have tail patterns and appendages of various degrees of sophistication that promote attacks at the rear rather than at the head.

Several species of pygmy owl bear "false eyes" on the back of the head, misleading predators into reacting as though they were the subject of an aggressive stare.

Studies of rear-wing damage support the hypothesis that this strategy is effective in deflecting attacks from the insect's head.

[66][67] Aggressive mimicry is found in predators or parasites that share some of the characteristics of a harmless species, allowing them to avoid detection by their prey or host; the strategy resembles a wolf in sheep's clothing, though no conscious deceptive intent is involved.

Leucochloridium, a genus of flatworm, matures in the digestive system of songbirds, their eggs then passing out of the bird in the faeces.

[14] A nematode (Myrmeconema neotropicum) changes the colour of the abdomen of workers of the canopy ant Cephalotes atratus to make it appear like the ripe fruits of Hyeronima alchorneoides.

This is common in plants with deceptive flowers that do not provide the reward they seem to offer and it may occur in Papua New Guinea fireflies, in which the signal of Pteroptyx effulgens is used by P. tarsalis to form aggregations to attract females.

The mechanism occurs in several orchids, including Epidendrum ibaguense which mimics flowers of Lantana camara and Asclepias curassavica, and is pollinated by monarch butterflies and perhaps hummingbirds.

Depending on the morphology of the flower, a pollen sac called a pollinium is attached to the head or abdomen of the male.

[94] Vavilovian mimicry is found in weeds that come to share characteristics with a domesticated plant through unintentional selection.

[96] Vavilovian mimics may eventually be domesticated themselves, as in the case of rye in wheat; Vavilov called these weed-crops secondary crops.