mimicry(redirected from Mimetism)
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mimicry,in biology, the advantageous resemblance of one species to another, often unrelated, species or to a feature of its own environment. (When the latter results from pigmentation it is classed as protective colorationprotective coloration,
coloration or color pattern of an animal that affords it protection from observation either by its predators or by its prey. The most widespread form of protective coloration is called cryptic resemblance, in which various effects that supplement the
..... Click the link for more information. .) Mimicry serves either to protect the mimic from its predators, as when the model is inedible or dangerous, or to deceive its prey (e.g., certain ant-eating spiders that themselves resemble ants). Mimicry occurs in both plants and animals but is most prevalent among insects, particularly butterflies and moths. The first scientific studies on the subject were published by English naturalists H. W. Bates (1862) and A. R. Wallace (1865). The Batesian theory is based on the operation of natural selectionselection.
In Darwinism, the mechanism of natural selection is considered of major importance in the process of evolution. Popular formulations sometimes envisage a struggle for existence in which direct competition for mates or for various factors in the environment (e.g.
..... Click the link for more information. : if, say, a harmless snake acquires a deceptive resemblance to a poisonous variety it is then more likely to escape its predators and thus to survive and propagate, producing offspring with the same appearance. Examples of mimicry are the resemblance of the viceroy butterfly to the monarch butterfly, which is repugnant to birds; harmless nettles that resemble stinging nettles; and the many fishes, crabs, and slugs of the Sargasso Sea that resemble the floating seaweed masses they inhabit.
See W. Wickler, Mimicry in Plants and Animals (tr. 1968); L. P. Brower, Mimicry and the Evolutionary Process (1988).
(also mimesis), a type of protective coloration and form by which an animal resembles an inanimate object in its environment, a plant, or another animal that is inedible to or protected against its predators. Enabling animals to survive in the struggle for existence, mimicry evolved as a result of natural selection.
The eggs of the oyster catcher, the plover, and other birds are similar in color and shape to pebbles. Some weevils and swallowtail caterpillars with dark and white coloration resemble bird droppings. Many animals bear a resemblance to plant organs. For example, the seahorse and the pipefish Syngnathus acus look like the seaweed in which they hide. Many snakes in tropical forests are indistinguishable from lianas. The cicada Hemidictya braziliana and the Australian spiny desert lizard, which live in prickly underbrush, are covered with thorns. The underwing Catocala fraxini, many arboreal long-horned beetles, jewel beetles, and tree-climbing geckos have the coloration and markings that enable them to blend in with tree bark. The buff-tip, or buff-tipped moth, resembles a broken-off branch: the ocher oval spot on the slightly bent-in ends of its wings looks like exposed wood. Many animal species, including the Lithosiinae, long-horned bettles, and spiders, resemble lichens in coloration and form. Geometrid and, particularly, phasmid caterpillars look like twigs.
Animal mimicry of leaves is so complete that it includes assuming the characteristic coloration of dry or living leaves, their shape, and their specific venation. For example, the Brazilian leaf fish looks like a dead leaf; Indo-Malayan butterflies of the genus Kallima, with their folded wings, mimic dry leaves; and the nocturnal moth Miniodes ornata has venation on the upper side of anterior wings, which is visible during the day and resembles leaf venation. Some tropical orthopterous insects—Cycloptera and Chitoniscus—also resemble leaves. The leaf insect Phyllium siccifolium from Sri Lanka has not only a leaf-shaped body but also leaf-shaped limbs. Many praying mantises bear a similarity in coloration and form to green or dried plant shoots; some plants (for example, Idolum diabolicuni) with brilliant flowers attract insects for pollination, which are subsequently eaten by mantises. The butterfly Hymenopus coronatus resembles an orchid.
Animals that are not protected against predators or that are nontoxic or edible (mimics) resemble conspicuously colored toxic or inedible animals (models). This form of mimicry has protective value if the mimic lives in the same locality as its model and is much less numerous. Protected animals have aposematic coloration and form, while the mimics have pseudoaposematic coloration and form. Mimicry is a means of defense only against highly organized predators (primarily vertebrates). Two forms of such mimicry are distinguished; they are named after the scientists who described them, H. Bates and F. Miiller. A resemblance between a species that is edible to a predator and one that is inedible is called Batesian mimicry. A classic example of this form of mimicry is provided by the South American butterflies Dismorphia astynome and Perrhybris pyrrha, which imitate brightly colored, inedible butterflies of the family Heliconidae, which have a disagreeable odor and taste. In Europe, some hawkmoths (for example, Haemorrhagia fuciformis), clearwings (for example, Aegeria apiformis], and many species of syrphus flies mimic such stinging insects as honeybees, bumblebees, and wasps. In Mullerian mimicry, several protected species resemble one another and develop mimicry rings, groups possessing the same coloration and shape. For example, many wasp species with the same body shape and color have yellow and black stripes. Poisonous insects (flea beetle, Pyrrhocoris apterus, blister beetle) are red with black spots. All the members of the ring benefit in that the predators recognize the unpalatability of one species and do not touch the other insect species that form part of the ring.
The effectiveness of mimicry is heightened by the behavior of the animals. For example, some butterflies resembling dry leaves make circular movements like falling leaves. Geometrid caterpillars, which resemble plant branches, are motionless during the day but active at night. Many leaf-shaped insects are active at the hottest time of the day, when predatory birds do little flying; they are motionless in the morning and evening, when the birds are most active. All insects instinctively select a background that corresponds to their coloration. Syrphus flies move their anterior legs to imitate the movements of antennae in bees and wasps and, like these insects, make a buzzing noise. Thus, in the course of evolution the appearance of mimicry was paralleled by the development and perfection of corresponding behavioral patterns.
REFERENCESShmal’gauzen, I. I. Problemy darvinizma. Leningrad, 1969.
Sheppard, F. M. Estestvennyi otbor i nasledstvennost’. Moscow, 1970. (Translated from English.)