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 (such as a predator) perceives the similarity between a mimic (the organism that has a resemblance) and a model (the organism it resembles) 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. In the case of mutualism, sometimes both groups are referred to as "co-mimics". It is often thought that models must be more abundant than mimics, but this is not so. Mimicry may involve numerous species; many harmless species such as hoverflies are Batesian mimics of strongly defended species such as wasps, while many such well-defended species form Mullerian mimicry rings, all resembling each other. Mimicry between prey species and their predators often involves three or more species.
In its broadest definition, mimicry can include non-living models. The specific terms masquerade and mimesis are sometimes used when the models are inanimate. For example, animals such as flower mantises, planthoppers, comma and geometer moth caterpillars resemble twigs, bark, leaves, bird droppings or flowers. Many animals bear eyespots, which are hypothesized to resemble the eyes of larger animals. They may not resemble any specific organism's eyes, and whether or not animals respond to them as eyes is also unclear. Nonetheless, eyespots are the subject of a rich contemporary literature. The model is usually another species, except in automimicry, where members of the species mimic other members, or other parts of their own bodies, and in inter-sexual mimicry, where members of one sex mimic members of the other.
Mimicry can result in an evolutionary arms race if mimicry negatively affects the model, and the model can evolve a different appearance from the mimic.p161 Mimicry should not be confused with other forms of convergent evolution that occurs when species come to resemble each other by adapting to similar lifestyles that have nothing to do with a common signal receiver. Mimics may have different models for different life cycle stages, or they may be polymorphic, with different individuals imitating different models, such as in Heliconius butterflies. Models themselves may have more than one mimic, though frequency dependent selection favours mimicry where models outnumber mimics. Models tend to be relatively closely related organisms, but mimicry of vastly different species is also known. Most known mimics are insects, though many other examples including vertebrates are also known. Plants and fungi may also be mimics, though less research has been carried out in this area.
Use of the word mimicry dates to 1637. It derives from the Greek term mimetikos, "imitative", in turn from mimetos, the verbal adjective of mimeisthai, "to imitate". Originally used to describe people, "mimetic" was used in zoology from 1851, "mimicry" from 1861.
Many types of mimicry have been described. An overview of each follows, highlighting the similarities and differences between the various forms. Classification is often based on function with respect to the mimic (e.g., avoiding harm). Some cases may belong to more than one class, e.g., automimicry and aggressive mimicry are not mutually exclusive, as one describes the species relationship between model and mimic, while the other describes the function for the mimic (obtaining food). The terminology used is not without debate and attempts to clarify have led to new terms being included. The term "masquerade" is sometimes used when the model is inanimate but it is differentiated from "crypsis" in its strict sense by the potential response of the signal receiver. In crypsis the receiver is assumed to not respond while a masquerader confuses the recognition system of the receiver that would otherwise seek the signaller. In the other forms of mimicry, the signal is not filtered out by the sensory system of the receiver. These are not mutually exclusive and in the evolution of wasp-like appearance, it has been argued that insects evolve to masquerade wasps since predatory wasps do not attack each other but this mimetic resemblance also deters vertebrate predators.
Defensive or protective mimicry takes place when organisms are able to avoid harmful encounters by deceiving enemies into treating them as something else.
The first three such cases discussed here entail mimicry of animals protected by warning coloration:
The fourth case, Vavilovian mimicry, where weeds resemble crops, involves humans as the agent of selection.
In Batesian mimicry the mimic shares signals similar to the model, but does not have the attribute that makes it unprofitable to predators (e.g., unpalatability). In other words, a Batesian mimic is a sheep in wolf's clothing. It is named after Henry Walter Bates, an English naturalist whose work on butterflies in the Amazon rainforest (described in The Naturalist on the River Amazons) was pioneering in this field of study. Mimics are less likely to be found out (for example by predators) when in low proportion to their model. This phenomenon is called negative frequency dependent selection, and it applies in most forms of mimicry. Batesian mimicry can only be maintained if the harm caused to the predator by eating a model outweighs the benefit of eating a mimic. The nature of learning is weighted in favor of the mimics, for a predator that has a bad first experience with a model tends to avoid anything that looks like it for a long time, and does not re-sample soon to see whether the initial experience was a false negative. However, if mimics become more abundant than models, then the probability of a young predator having a first experience with a mimic increases. Such systems are therefore most likely to be stable where both the model and the mimic occur, and where the model is more abundant than the mimic. This is not the case in Müllerian mimicry, which is described next.
There are many Batesian mimics in the order Lepidoptera. Consul fabius and Eresia eunice imitate unpalatable Heliconius butterflies such as H. ismenius. Limenitis arthemis imitate the poisonous pipeline swallowtail (Battus philenor). Several palatable moths produce ultrasonic click calls to mimic unpalatable tiger moths. Octopuses of the genus Thaumoctopus (the mimic octopus) are able to intentionally alter their body shape and coloration to resemble dangerous sea snakes or lionfish. In the Amazon, the helmeted woodpecker (Dryocopus galeatus), a rare species which lives in the Atlantic Forest of Brazil, Paraguay, and Argentina, has a similar red crest, black back, and barred underside to two larger woodpeckers: Dryocopus lineatus and Campephilus robustus. This mimicry reduces attacks on Dryocopus galeatus from other animals. Scientists had falsely believed that D. galeatus was a close cousin of the other two species, because of the visual similarity, and because the three species live in the same habitat and eat similar food. Batesian mimicry also occurs in the plant kingdom, such as the chameleon vine, which adapts its leaf shape and colour to match that of the plant it is climbing, such that its edible leaves appear to be the less desirable leaves of its host.
Müllerian mimicry, named for the German naturalist Fritz Müller, describes a situation where two or more species have similar warning or aposematic signals and both share genuine anti-predation attributes (e.g. being unpalatable). At first, Bates could not explain why this should be so—if both were harmful why did one need to mimic another? Müller put forward the first explanation for this phenomenon: if a common predator confuses two species, individuals in both those species are more likely to survive. This type of mimicry is unique in several respects. Firstly, both the mimic and the model benefit from the interaction, which could thus be classified as mutualism in this respect. The signal receiver is also advantaged by this system, despite being deceived about species identity, as it avoids potentially harmful encounters. The usually clear distinction between mimic and model is also blurred. Where one species is scarce and another abundant, the rare species can be said to be the mimic. When both are present in similar numbers, however, it is more realistic to speak of each as a co-mimic than of distinct 'mimic' and 'model' species, as their warning signals tend to converge. Also, the two species may exist on a continuum from harmless to highly noxious, so Batesian mimicry grades smoothly into Müllerian convergence.
The monarch butterfly (Danaus plexippus) is a member of a Müllerian complex with the viceroy butterfly (Limenitis archippus), sharing coloration patterns and display behaviour. The viceroy has subspecies with somewhat different coloration, each closely matching the local Danaus species. For example, in Florida, the pairing is of the viceroy and the queen butterfly, whereas in Mexico the viceroy resembles the soldier butterfly. The viceroy is thus involved in three different Müllerian pairs. This example was long believed to be Batesian, with the viceroy mimicking the monarch, but the viceroy is actually the more unpalatable species. The genus Morpho is palatable, but some species (such as M. amathonte) are strong fliers; birds – even species that specialize in catching butterflies on the wing – find it hard to catch them. The conspicuous blue coloration shared by most Morpho species may be Müllerian, or may be "pursuit aposematism". The "orange complex" of distasteful butterfly species includes the heliconiines Agraulis vanillae, Dryadula phaetusa, and Dryas iulia. At least seven species of millipedes in the genera Apheloria and Brachoria (Xystodesmidae) form a Müllerian mimicry ring in the eastern United States, in which unrelated polymorphic species converge on similar colour patterns where their range overlaps.
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 answer for the theoretical difficulties a predator species faces when associating an aposematic phenotype of potentially dangerous animals, such as the coral snake, with unprofitability when the predator has an increased risk of death, negating any learned behaviour. The theory was developed by the German biologist Wolfgang Wickler in a chapter of Mimicry in Plants and Animals, who named it after the German herpetologist Robert Mertens. Sheppard points out that Hecht and Marien put forward a similar hypothesis ten years earlier. This scenario is a little more difficult to understand, since in other types of mimicry it is usually the most harmful species that is the model. But if a predator dies, it cannot learn to recognize a warning signal, e.g., bright colours in a certain pattern. In other words, there is no advantage in being aposematic for an organism that is likely to kill any predator it succeeds in poisoning; such an animal is better off being camouflaged, to avoid attacks altogether. If, however, there were some other species that were harmful but not deadly as well as aposematic, the predator could learn to recognize its particular warning colours and avoid such animals. A deadly species could then profit by mimicking the less dangerous aposematic organism if this reduces the number of attacks. The exception here, ignoring any chance of animals learning by watching a conspecific die (see Jouventin et al. for a discussion of observational learning and mimicry), is the possibility of not having to learn that it is harmful in the first place: instinctive genetic programming to be wary of certain signals. In this case, other organisms could benefit from this programming, and Batesian or Müllerian mimics of it could potentially evolve. In fact, it has been shown that some species do have an innate recognition of certain aposematic warnings. Hand-reared turquoise-browed motmots (Eumomota superciliosa), avian predators, instinctively avoid snakes with red and yellow rings. Other colours with the same pattern, and even red and yellow stripes with the same width as rings, were tolerated. However, models with red and yellow rings were feared, with the birds flying away and giving alarm calls in some cases. This provides an alternative explanation to Mertensian mimicry. See Greene and McDiarmid for a review of the subject.
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. It has also been suggested that this system could be an instance of pseudomimicry, the similar colour patterns having evolved independently in similar habitats.
Vavilovian mimicry is found in weeds that come to share characteristics with a domesticated plant through artificial selection. It is named after Russian botanist and geneticist Nikolai Vavilov. Selection against the weed may occur either by manually killing the weed, or by separating its seeds from those of the crop by winnowing.
Vavilovian mimicry presents an illustration of unintentional (or rather 'anti-intentional') selection by man. Weeders do not want to select weeds and their seeds that look increasingly like cultivated plants, yet there is no other option. For example, early barnyard grass, Echinochloa oryzoides, is a weed in rice fields and looks similar to rice; its seeds are often mixed in rice and have become difficult to separate through Vavilovian mimicry. Vavilovian mimics may eventually be domesticated themselves, as in the case of rye in wheat; Vavilov called these weed-crops secondary crops.
Vavilovian mimicry can be classified as defensive mimicry, in that the weed mimics a protected species. This bears strong similarity to Batesian mimicry in that the weed does not share the properties that give the model its protection, and both the model and the dupe (in this case people) are harmed by its presence. There are some key differences, though; in Batesian mimicry, the model and signal receiver are enemies (the predator would eat the protected species if it could), whereas here the crop and its human growers are in a mutualistic relationship: the crop benefits from being dispersed and protected by people, despite being eaten by them. In fact, the crop's only "protection" relevant here is its usefulness to humans. Secondly, the weed is not eaten, but simply destroyed. The only motivation for killing the weed is its effect on crop yields. Finally, this type of mimicry does not occur in ecosystems unaltered by humans.
Gilbertian mimicry involves only two species. The potential host (or prey) drives away its parasite (or predator) by mimicking it, the reverse of host-parasite aggressive mimicry. It was coined by Pasteur as a phrase for such rare mimicry systems, and is named after the American ecologist Lawrence E. Gilbert.
Gilbertian mimicry occurs in the genus Passiflora. The leaves of this plant contain toxins that deter herbivorous animals. However, some Heliconius butterfly larvae have evolved enzymes that break down these toxins, allowing them to specialize on this genus. This has created further selection pressure on the host plants, which have evolved stipules that mimic mature Heliconius eggs near the point of hatching. These butterflies tend to avoid laying eggs near existing ones, which helps avoid exploitative intraspecific competition between caterpillars — those that lay on vacant leaves provide their offspring with a greater chance of survival. Most Heliconius larvae are cannibalistic, meaning that on leaves older eggs hatch first and eat the new arrivals. Thus, it seems that such plants have evolved egg dummies under selection pressure from these grazing herbivore enemies. In addition, the decoy eggs are also nectaries, attracting predators of the caterpillars such as ants and wasps as a further defence.
Browerian mimicry, named after Lincoln P. Brower and Jane Van Zandt Brower, is a postulated form of automimicry; where the model belongs to the same species as the mimic. This is the analogue of Batesian mimicry within a single species, and occurs when there is a palatability spectrum within a population. Examples include the monarch and the queen from the Danainae subfamily, which feed on milkweed species of varying toxicity. These species store toxins from its host plant, which are maintained even in the adult (imago) form. As levels of toxin vary depending on diet during the larval stage, some individuals are more toxic than others. Less palatable organisms, therefore, mimic more dangerous individuals, with their likeness already perfected.
This is not always the case, however. In sexually dimorphic species, one sex may be more of a threat than the other, which could mimic the protected sex. Evidence for this possibility is provided by the behaviour of a monkey from Gabon, which regularly ate male moths of the genus Anaphe, but promptly stopped after it tasted a noxious female.
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; this can be compared with the story of the wolf in sheep's clothing as long as it is understood that no conscious deceptive intent is involved. The mimic may resemble the prey or host itself, or another organism that is either neutral or beneficial to the signal receiver. In this class of mimicry, the model may be affected negatively, positively or not at all. Just as parasites can be treated as a form of predator, host-parasite mimicry is treated here as a subclass of aggressive mimicry.
The mimic may have a particular significance for duped prey. One such case is spiders, amongst which aggressive mimicry is quite common both in luring prey and disguising stealthily approaching predators. One case is the golden orb weaver (Nephila clavipes), which spins a conspicuous golden colored web in well-lit areas. Experiments show that bees are able to associate the webs with danger when the yellow pigment is not present, as occurs in less well-lit areas where the web is much harder to see. Other colours were also learned and avoided, but bees seemed least able to effectively associate yellow-pigmented webs with danger. Yellow is the colour of many nectar-bearing flowers, however, so perhaps avoiding yellow is not worthwhile. Another form of mimicry is based not on colour but pattern. Species such as the silver argiope (Argiope argentata) employ prominent patterns in the middle of their webs, such as zigzags. These may reflect ultraviolet light, and mimic the pattern seen in many flowers known as nectar guides. Spiders change their web day to day, which can be explained by the ability of bees to remember web patterns. Bees are able to associate a certain pattern with a spatial location, meaning the spider must spin a new pattern regularly or suffer diminishing prey capture.
Another case is where males are lured towards what seems to be a sexually receptive female. The model in this situation is the same species as the dupe. Beginning in the 1960s, James E. Lloyd's investigation of female fireflies of the genus Photuris revealed they emit the same light signals that females of the genus Photinus use as a mating signal. Further research showed male fireflies from several different genera are attracted to these "femmes fatales", and are subsequently captured and eaten. Female signals are based on that received from the male, each female having a repertoire of signals matching the delay and duration of the female of the corresponding species. This mimicry may have evolved from non-mating signals that have become modified for predation.
The listrosceline katydid Chlorobalius leucoviridis of inland Australia is capable of attracting male cicadas of the tribe Cicadettini by imitating the species-specific reply clicks of sexually receptive female cicadas. This example of acoustic aggressive mimicry is similar to the Photuris firefly case in that the predator's mimicry is remarkably versatile – playback experiments show that C. leucoviridis is able to attract males of many cicada species, including cicadettine cicadas from other continents, even though cicada mating signals are species-specific.
Luring is not a necessary condition however, as the predator still has a significant advantage simply by not being identified as such. They may resemble a mutualistic symbiont or a species of little relevance to the prey.
A case of the latter situation is a species of cleaner fish and its mimic, though in this example the model is greatly disadvantaged by the presence of the mimic. Cleaner fish are the allies of many other species, which allow them to eat their parasites and dead skin. Some allow the cleaner to venture inside their body to hunt these parasites. However, one species of cleaner, the bluestreak cleaner wrasse (Labroides dimidiatus), is the unknowing model of a mimetic species, the sabre-toothed blenny (Aspidontus taeniatus). This wrasse resides in coral reefs in the Indian and the Pacific Oceans, and is recognized by other fishes that then let it clean them. Its imposter, a species of blenny, lives in the Indian Ocean—and not only looks like it in terms of size and coloration, but even mimics the cleaner's "dance". Having fooled its prey into letting its guard down, it then bites it, tearing off a piece of its fin before fleeing. Fish grazed on in this fashion soon learn to distinguish mimic from model, but because the similarity is close between the two they become much more cautious of the model as well, so both are affected. Due to victims' ability to discriminate between foe and helper, the blennies have evolved close similarity, right down to the regional level.
Another interesting example that does not involve any luring is the zone-tailed hawk, which resembles the turkey vulture. It flies amongst the vultures, suddenly breaking from the formation and ambushing its prey. Here the hawk's presence is of no evident significance to the vultures, affecting them neither negatively or positively.
Parasites can also be aggressive mimics, though the situation is somewhat different from those outlined previously. Some predators have a feature that draws prey; parasites can also mimic their hosts' natural prey, but are eaten themselves, a pathway into their host. Leucochloridium, a genus of flatworm, matures in the digestive system of songbirds, their eggs then passing out of the bird in the faeces. They are then taken up by Succinea, a terrestrial snail. The eggs develop in this intermediate host, and must then find a suitable bird to mature in. Since the host birds do not eat snails, the sporocyst has another strategy to reach its host's intestine. They are brightly coloured and move in a pulsating fashion. A sporocyst-sac pulsates in the snail's eye stalks, coming to resemble an irresistible meal for a songbird. In this way, it can bridge the gap between hosts, allowing it to complete its life cycle. 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. It also changes the behaviour of the ant so that the gaster (rear part) is held raised. This presumably increases the chances of the ant being eaten by birds. The droppings of birds are collected by other ants and fed to their brood, thereby helping to spread the nematode.
In an unusual case, planidium larvae of some beetles of the genus Meloe form a group and produce a pheromone that mimics the sex attractant of its host bee species. When a male bee arrives and attempts to mate with the mass of larvae, they climb onto his abdomen. From there, they transfer to a female bee, and from there to the bee nest to parasitize the bee larvae.
Host-parasite mimicry is a two species system where a parasite mimics its own host. Cuckoos are a canonical example of brood parasitism, a form of parasitism where the mother has its offspring raised by another unwitting individual, often from a different species, cutting down the biological mother's parental investment in the process. The ability to lay eggs that mimic the host eggs is the key adaptation. The adaptation to different hosts is inherited through the female line in so-called gentes (gens, singular). Cases of intraspecific brood parasitism, where a female lays in a conspecific's nest, as illustrated by the goldeneye duck (Bucephala clangula), do not represent a case of mimicry. A different mechanism is chemical mimicry, as seen in the parasitic butterfly Phengaris rebeli, which parasitizes the ant species Myrmica schencki by releasing chemicals that fool the worker ants to believe that the caterpillar larvae are ant larvae, and enable the P. rebeli larvae to be brought directly into the M. schencki nest. Parasitic (cuckoo) bumblebees (formerly Psithyrus, now included in Bombus) resemble their hosts more closely than would be expected by chance, at least in areas like Europe where parasite-host co-speciation is common. However, this is explainable as Müllerian mimicry, rather than requiring the parasite's coloration to deceive the host and thus constitute aggressive mimicry.
Reproductive mimicry occurs when the actions of the dupe directly aid in the mimic's reproduction. 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. Other forms of mimicry have a reproductive component, such as Vavilovian mimicry involving seeds, vocal mimicry in birds, and aggressive and Batesian mimicry in brood parasite-host systems.
Bakerian mimicry, named after Herbert G. Baker, is a form of automimicry where female flowers mimic male flowers of their own species, cheating pollinators out of a reward. This reproductive mimicry may not be readily apparent as members of the same species may still exhibit some degree of sexual dimorphism. It is common in many species of Caricaceae.
Like Bakerian mimicry, Dodsonian mimicry is a form of reproductive floral mimicry, but the model belongs to a different species than the mimic. The name refers to Calaway H. Dodson. By providing similar sensory signals as the model flower, it can lure its pollinators. Like Bakerian mimics, no nectar is provided. Epidendrum ibaguense (Orchidaceae) resembles flowers of Lantana camara and Asclepias curassavica, and is pollinated by monarch butterflies and perhaps hummingbirds. Similar cases are seen in some other species of the same family. The mimetic species may still have pollinators of its own though. For example, a lamellicorn beetle, which usually pollinates correspondingly colored Cistus flowers, is also known to aid in pollination of Ophrys species that are normally pollinated by bees.
Pseudocopulation occurs when a flower mimics a female of a certain insect species, inducing the males to try to copulate with the flower. This is much like the aggressive mimicry in fireflies described previously, but with a more benign outcome for the pollinator. This form of mimicry has been called Pouyannian mimicry, after Maurice-Alexandre Pouyanne, who first described the phenomenon. It is most common in orchids, which mimic females of the order Hymenoptera (generally bees and wasps), and may account for around 60% of pollinations. Depending on the morphology of the flower, a pollen sac called a pollinia is attached to the head or abdomen of the male. This is then transferred to the stigma of the next flower the male tries to inseminate, resulting in pollination. Visual mimicry is the most obvious sign of this deception for humans, but the visual aspect may be minor or non-existent. It is the senses of touch and olfaction that are most important.
Inter-sexual mimicry occurs when individuals of one sex in a species mimic members of the opposite sex to facilitate sneak mating. An example is the three male forms of the marine isopod Paracerceis sculpta. Alpha males are the largest and guard a harem of females. Beta males mimic females and manage to enter the harem of females without being detected by the alpha males allowing them to mate. Gamma males are the smallest males and mimic juveniles. This also allows them to mate with the females without the alpha males detecting them. Similarly, among common side-blotched lizards, some males mimic the yellow throat coloration and even mating rejection behaviour of the other sex to sneak matings with guarded females. These males look and behave like unreceptive females. This strategy is effective against "usurper" males with orange throats, but ineffective against blue throated "guarder" males, which chase them away. Female spotted hyenas have pseudo-penises that make them look like males.
Automimicry or intraspecific mimicry occurs within a single species. One form of such mimicry is where one part of an organism's body resembles another part. For example, the tails of some snakes resemble their heads; they move backwards when threatened and present the predator with the tail, improving their chances of escape without fatal harm. Some fishes have eyespots near their tails, and when mildly alarmed swim slowly backwards, presenting the tail as a head. 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.
Some writers use the term "automimicry" when the mimic imitates other morphs within the same species. For example, in a species where males mimic females or vice versa, this may be an instance of sexual mimicry in evolutionary game theory. Examples are found in some species of birds, fishes, and lizards. Quite elaborate strategies along these lines are known, such as the well-known "scissors, paper, rock" mimicry in Uta stansburiana, but there are qualitatively different examples in many other species, such as some Platysaurus.
Many species of insects are toxic or distasteful when they have fed on certain plants that contain chemicals of particular classes, but not when they have fed on plants that lack those chemicals. For instance, some species of the subfamily Danainae feed on various species of the Asclepiadoideae in the family Apocynaceae, which render them poisonous and emetic to most predators. Such insects frequently are aposematically coloured and patterned. When feeding on innocuous plants however, they are harmless and nutritious, but a bird that once has sampled a toxic specimen is unlikely to eat harmless specimens that have the same aposematic coloration. When regarded as mimicry of toxic members of the same species, this too may be seen as automimicry.
Some species of caterpillar, such as many hawkmoths (Sphingidae), have eyespots on their anterior abdominal segments. When alarmed, they retract the head and the thoracic segments into the body, leaving the apparently threatening large eyes at the front of the visible part of the body.
Many insects have filamentous "tails" at the ends of their wings and patterns of markings on the wings themselves. These combine to create a "false head". This misdirects predators such as birds and jumping spiders (Salticidae). Spectacular examples occur in the hairstreak butterflies; when perching on a twig or flower, they commonly do so upside down and shift their rear wings repeatedly, causing antenna-like movements of the "tails" on their wings. Studies of rear-wing damage support the hypothesis that this strategy is effective in deflecting attacks from the insect's head.
Some forms of mimicry do not fit easily within the classification given above. Floral mimicry is induced by the discomycete fungus Monilinia vaccinii-corymbosi. In this unusual case, a fungal plant pathogen infects leaves of blueberries, causing them to secrete sugars, in effect mimicking the nectar of flowers. To the naked eye the leaves do not look like flowers, yet they still attract pollinating insects like bees using an ultraviolet signal. This case is unusual, in that the fungus benefits from the deception but it is the leaves that act as mimics, being harmed in the process. It is similar to host-parasite mimicry, but the host does not receive the signal. It has a little in common with automimicry, but the plant does not benefit from the mimicry, and the action of the pathogen is required to produce it.
It is widely accepted that mimicry evolves as a positive adaptation. The lepidopterist and novelist Vladimir Nabokov however argued that although natural selection might stabilize a "mimic" form, it would not be necessary to create it.
The most widely accepted model used to explain the evolution of mimicry in butterflies is the two-step hypothesis. The first step involves mutation in modifier genes that regulate a complex cluster of linked genes that cause large changes in morphology. The second step consists of selections on genes with smaller phenotypic effects, creating an increasingly close resemblance. This model is supported by empirical evidence that suggests that a few single point mutations cause large phenotypic effects, while numerous others produce smaller effects. Some regulatory elements collaborate to form a supergene for the development of butterfly color patterns. The model is supported by computational simulations of population genetics. The Batesian mimicry in Papilio polytes is controlled by the doublesex gene.
Some mimicry is imperfect. Natural selection drives mimicry only far enough to deceive predators. For example, when predators avoid a mimic that imperfectly resembles a coral snake, the mimic is sufficiently protected.
Convergent evolution is an alternative explanation for why organisms such as coral reef fish and benthic marine invertebrates such as sponges and nudibranchs have come to resemble each other.
Viceroys are as unpalatable as monarchs, and significantly more unpalatable than queens from representative Florida populations.
Aggressive mimicry is a form of mimicry in which predators, parasites or parasitoids share similar signals, using a harmless model, allowing them to avoid being correctly identified by their prey or host. Zoologists have repeatedly compared this strategy to a wolf in sheep's clothing. In its broadest sense, aggressive mimicry could include various types of exploitation, as when an orchid exploits a male insect by mimicking a sexually receptive female (see pseudocopulation), but will here be restricted to forms of exploitation involving feeding. An alternative term Peckhamian mimicry (after George and Elizabeth Peckham) has been suggested, but is seldom used. The metaphor of a wolf in sheep's clothing can be used as an analogy, but with the caveat that mimics are not intentionally deceiving their prey. For example, indigenous Australians who dress up as and imitate kangaroos when hunting would not be considered aggressive mimics, nor would a human angler, though they are undoubtedly practising self-decoration camouflage. Treated separately is molecular mimicry, which shares some similarity; for instance a virus may mimic the molecular properties of its host, allowing it access to its cells.
Aggressive mimicry is opposite in principle to defensive mimicry, where the mimic generally benefits from being treated as harmful. The mimic may resemble its own prey, or some other organism which is beneficial or at least not harmful to the prey. The model, i.e. the organism being 'imitated', may experience increased or reduced fitness, or may not be affected at all by the relationship. On the other hand, the signal receiver inevitably suffers from being tricked, as is the case in most mimicry complexes.
Aggressive mimicry often involves the predator employing signals which draw its potential prey towards it, a strategy which allows predators to simply sit and wait for prey to come to them. The promise of food or sex are most commonly used as lures. However, this need not be the case; as long as the predator's true identity is concealed, it may be able to approach prey more easily than would otherwise be the case. In terms of species involved, systems may be composed of two or three species; in two-species systems the signal receiver, or "dupe", is the model.
In terms of the visual dimension, the distinction between aggressive mimicry and camouflage is not always clear. Authors such as Wickler have emphasized the significance of the signal to its receiver as delineating mimicry from camouflage. However, it is not easy to assess how 'significant' a signal may be for the dupe, and the distinction between the two can thus be rather fuzzy. Mixed signals may be employed: aggressive mimics often have a specific part of the body sending a deceptive signal, with the rest being hidden or camouflaged.Animal coloration
Animal coloration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. Some animals are brightly colored, while others are hard to see. In some species, such as the peafowl, the male has strong patterns, conspicuous colors and is iridescent, while the female is far less visible.
There are several separate reasons why animals have evolved colors. Camouflage enables an animal to remain hidden from view. Animals use color to advertise services such as cleaning to animals of other species; to signal their sexual status to other members of the same species; and in mimicry, taking advantage of the warning coloration of another species. Some animals use flashes of color to divert attacks by startling predators. Zebras may possibly use motion dazzle, confusing a predator's attack by moving a bold pattern rapidly. Some animals are colored for physical protection, with pigments in the skin to protect against sunburn, while some frogs can lighten or darken their skin for temperature regulation. Finally, animals can be colored incidentally. For example, blood is red because the heme pigment needed to carry oxygen is red. Animals colored in these ways can have striking natural patterns.
Animals produce color in both direct and indirect ways. Direct production occurs through the presence of visible colored cells known as pigment which are particles of colored material such as freckles. Indirect production occurs by virtue of cells known as chromatophores which are pigment-containing cells such as hair follicles. The distribution of the pigment particles in the chromatophores can change under hormonal or neuronal control. For fishes it has been demonstrated that chromatophores may respond directly to environmental stimuli like visible light, UV-radiation, temperature, pH, chemicals, etc. Color change helps individuals in becoming more or less visible and is important in agonistic displays and in camouflage. Some animals, including many butterflies and birds, have microscopic structures in scales, bristles or feathers which give them brilliant iridescent colors. Other animals including squid and some deep-sea fish can produce light, sometimes of different colors. Animals often use two or more of these mechanisms together to produce the colors and effects they need.Ant mimicry
Ant mimicry or myrmecomorphy is mimicry of ants by other organisms. Ants are abundant all over the world, and potential predators that rely on vision to identify their prey, such as birds and wasps, normally avoid them, because they are either unpalatable or aggressive. Spiders are the most common ant mimics. Additionally, some arthropods mimic ants to escape predation (protective mimicry), while others mimic ants anatomically and behaviourally to hunt ants in aggressive mimicry.
In Wasmannian mimicry, mimic and model live commensally together; in the case of ants, the model is an inquiline in the ants' nest. Wasmannian mimics may also be Batesian or aggressive mimics. To overcome ants' powerful defences, mimics may imitate ants chemically with ant-like pheromones, visually (as in Batesian mimicry), or by imitating an ant's surface microstructure for tactile mimicry.Aposematism
Aposematism (from Ancient Greek ἀπό apo away, σῆμα sema sign) refers to the appearance of an animal that warns predators it is toxic, distasteful, or dangerous. This warning signal is associated with the unprofitability of a prey item to potential predators. The unprofitability may consist of any defences which make the prey difficult to eat, such as toxicity, foul taste or smell, sharp spines, or aggressive nature. Aposematism always involves an advertising signal which may take the form of conspicuous animal coloration, sounds, odours or other perceivable characteristics. Aposematic signals are beneficial for both the predator and prey, since both avoid potential harm.
The term was coined by Edward Bagnall Poulton for Alfred Russel Wallace's concept of warning coloration. Aposematism is exploited in Müllerian mimicry, where species with strong defences evolve to resemble one another. By mimicking similarly coloured species, the warning signal to predators is shared, causing them to learn more quickly at less of a cost to each of the species.
A genuine aposematic signal that a species actually possesses chemical or physical defences is not the only way to deter predators. In Batesian mimicry, a mimicking species resembles an aposematic model closely enough to share the protection, while many species have bluffing deimatic displays which may startle a predator long enough to enable an otherwise undefended prey to escape.Batesian mimicry
Batesian mimicry is a form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both. It is named after the English naturalist Henry Walter Bates, after his work on butterflies in the rainforests of Brazil.
Batesian mimicry is the most commonly known and widely studied of mimicry complexes, such that the word mimicry is often treated as synonymous with Batesian mimicry. There are many other forms however, some very similar in principle, others far separated. It is often contrasted with Müllerian mimicry, a form of mutually beneficial convergence between two or more harmful species. However, because the mimic may have a degree of protection itself, the distinction is not absolute. It can also be contrasted with functionally different forms of mimicry. Perhaps the sharpest contrast here is with aggressive mimicry, where a predator or parasite mimics a harmless species, avoiding detection and improving its foraging success.
The imitating species is called the mimic, while the imitated species (protected by its toxicity, foul taste or other defenses) is known as the model. The predatory species mediating indirect interactions between the mimic and the model is variously known as the [signal] receiver, dupe or operator. By parasitizing the honest warning signal of the model, the Batesian mimic gains an advantage, without having to go to the expense of arming itself. The model, on the other hand, is disadvantaged, along with the dupe. If impostors appear in high numbers, positive experiences with the mimic may result in the model being treated as harmless. At higher frequency there is also a stronger selective advantage for the predator to distinguish mimic from model. For this reason, mimics are usually less numerous than models, an instance of frequency dependent selection. Some mimetic populations have evolved multiple forms (polymorphism), enabling them to mimic several different models and thereby to gain greater protection. Batesian mimicry is not always perfect. A variety of explanations have been proposed for this, including limitations in predators' cognition.
While visual signals have attracted most study, Batesian mimicry can employ deception of any of the senses; some moths mimic the ultrasound warning signals sent by unpalatable moths to bat predators, constituting auditory Batesian mimicry.Brood parasite
Brood parasites are organisms that rely on others to raise their young. The strategy appears among birds, insects and some fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were its own, using brood mimicry, for example by having eggs that resemble the host's (egg mimicry).
Brood parasitism relieves the parasitic parents from the investment of rearing young or building nests for the young, enabling them to spend more time on other activities such as foraging and producing further offspring. Bird parasite species mitigate the risk of egg loss by distributing eggs amongst a number of different hosts. As this behaviour damages the host, it often results in an evolutionary arms race between parasite and host as the pair of species coevolve.Coloration evidence for natural selection
Animal coloration provided important early evidence for evolution by natural selection, at a time when little direct evidence was available. Three major functions of coloration were discovered in the second half of the 19th century, and subsequently used as evidence of selection: camouflage (protective coloration); mimicry, both Batesian and Müllerian; and aposematism.
Charles Darwin's On the Origin of Species was published in 1859, arguing from circumstantial evidence that selection by human breeders could produce change, and that since there was clearly a struggle for existence, that natural selection must be taking place. But he lacked an explanation either for genetic variation or for heredity, both essential to the theory. Many alternative theories were accordingly considered by biologists, threatening to undermine Darwinian evolution.
Some of the first evidence was provided by Darwin's contemporaries, the naturalists Henry Walter Bates and Fritz Müller. They described forms of mimicry that now carry their names, based on their observations of tropical butterflies. These highly specific patterns of coloration are readily explained by natural selection, since predators such as birds which hunt by sight will more often catch and kill insects that are less good mimics of distasteful models than those that are better mimics; but the patterns are otherwise hard to explain.
Darwinists such as Alfred Russel Wallace and Edward Bagnall Poulton, and in the 20th century Hugh Cott and Bernard Kettlewell, sought evidence that natural selection was taking place. Wallace noted that snow camouflage, especially plumage and pelage that changed with the seasons, suggested an obvious explanation as an adaptation for concealment. Poulton's 1890 book, The Colours of Animals, written during Darwinism's lowest ebb, used all the forms of coloration to argue the case for natural selection. Cott described many kinds of camouflage, and in particular his drawings of coincident disruptive coloration in frogs convinced other biologists that these deceptive markings were products of natural selection. Kettlewell experimented on peppered moth evolution, showing that the species had adapted as pollution changed the environment; this provided compelling evidence of Darwinian evolution.Crypsis
In ecology, crypsis is the ability of an animal to avoid observation or detection by other animals. It may be a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean lifestyle and mimicry. Crypsis can involve visual, olfactory (with pheromones), or auditory concealment. When it is visual, the term cryptic coloration, effectively a synonym for animal camouflage, is sometimes used, but many different methods of camouflage are employed by animals.Dazzled and Deceived
Dazzled and Deceived: Mimicry and Camouflage is a 2009 book on camouflage and mimicry, in nature and military usage, by the science writer and journalist Peter Forbes. It covers the history of these topics from the 19th century onwards, describing the discoveries of Henry Walter Bates, Alfred Russel Wallace and Fritz Müller, especially their studies of butterflies in the Amazon. The narrative also covers 20th-century military camouflage, begun by the painter Abbot Thayer who advocated disruptive coloration and countershading and continued in the First World War by the zoologist John Graham Kerr and the marine artist Norman Wilkinson, who developed dazzle camouflage. In the Second World War, the leading expert was Hugh Cott, who advised the British army on camouflage in the Western Desert.
The book was well received by critics, both military historians and biologists, and won the 2011 Warwick Prize for Writing.Eyespot (mimicry)
An eyespot (sometimes ocellus) is an eye-like marking. They are found in butterflies, reptiles, cats, birds and fish.
Eyespots may be a form of mimicry in which a spot on the body of an animal resembles an eye of a different animal to deceive potential predator or prey species; a form of self-mimicry, to draw a predator's attention away from the most vulnerable body parts; or to appear as an inedible or dangerous animal. Eyespots may play a role in intraspecies communication or courtship; the best-known example is probably the eyespots on a peacock's display feathers.
Eyespots are not necessarily adaptations, but may in some cases be spandrels, accidental artifacts of pattern formation.
The morphogenesis of eyespots is controlled by a small number of genes active in embryonic development of a wide range of animals, including Engrailed, Distal-less, Hedgehog, Antennapedia, and the Notch signaling pathway.Henry Walter Bates
Henry Walter Bates (8 February 1825 in Leicester – 16 February 1892 in London) was an English naturalist and explorer who gave the first scientific account of mimicry in animals. He was most famous for his expedition to the rainforests of the Amazon with Alfred Russel Wallace, starting in 1848. Wallace returned in 1852, but lost his collection on the return voyage when his ship caught fire. When Bates arrived home in 1859 after a full eleven years, he had sent back over 14,712 species (mostly of insects) of which 8,000 were (according to Bates, but see Van Wyhe) new to science. Bates wrote up his findings in his best-known work, The Naturalist on the River Amazons.Impersonator
An impersonator is someone who imitates or copies the behavior or actions of another. There are many reasons for impersonating someone:
Entertainment: An entertainer impersonates a celebrity, generally for entertainment, and makes fun of their personal lives, recent scandals and known behavior patterns. Especially popular objects of impersonation are Elvis (see Elvis impersonator), Michael Jackson, Abraham Lincoln, and Lenin. Entertainers who impersonate multiple celebrities as part of their act, can be sorted into impressionists and celebrity impersonators.
Crime: As part of a criminal act such as identity theft. This is usually where the criminal is trying to assume the identity of another, in order to commit fraud, such as accessing confidential information, or to gain property not belonging to them. Also known as social engineering and impostors.
Decoys, used as a form of protection for political and military figures. This involves an impersonator who is employed (or forced) to perform during public appearances, to mislead observers.
Sowing discord, causing people to fight, or dislike each other for social, business or political gain.
Companionship: a rental family service provides actors portraying friends or family for platonic purposes.Kalabhavan
Kalabhavan (Malayalam: കലാഭവന്, meaning "the house of arts"), also known as Cochin Kalabhavan, is a centre for learning performing arts in Kochi, India. Kalabhavan is notable and known for being the first organized performing mimicry group in Kerala and which popularised the art of mimicry in the state of Kerala. Ever since its founding, Kalabhavan has served as a grooming centre for acting aspirants. Hence, Kalabhavan has contributed numerous actors as well as film directors to Malayalam cinema.
Founded on 3 September 1969, by C.M.I. priest Fr. Abel, what Kalabhavan initially took up was producing Christian religious songs. Later they moved on to 'Ganamela' (Concerts for film songs). Mimicry performances of individual artists were used as 'fillers' in between stage programs. Later, mimicry was organized as a team event to form the now popular 'Mimics Parade'.
The professional mimicry troupe of Kalabhavan began with a team of 6 consisting of Siddique, Lal, Anzar, K. S. Prasad Varkkichan and Rahman (comedy actor). It was this team that invented 'Mimics Parade' in the present form.
In 2015 Kalabhavan opened its UAE centre at Sharjah (Kalabhavan Sharjah)List of typefaces
This is a list of typefaces, which are separated into groups by distinct artistic differences. The list includes typefaces that have articles or that are referenced. Superfamilies that fall under more than one category have an asterisk (*) after their name.Mimics and Gesture Theatre
The Mimics and Gesture Theatre is a theatre located in the Eastern Administrative Okrug of Moscow, Russia. It offers special sessions for deaf people.
The theatre is located in Izmailovsky bulv., 39/41 (Pervomayskaya metro station)Müllerian mimicry
Müllerian mimicry is a natural phenomenon in which two or more unprofitable (often, distasteful) species, that may or may not be closely related and share one or more common predators, have come to mimic each other's honest warning signals, to their mutual benefit, since predators can learn to avoid all of them with fewer experiences. It is named after the German naturalist Fritz Müller, who first proposed the concept in 1878, supporting his theory with the first mathematical model of frequency-dependent selection, one of the first such models anywhere in biology.Müllerian mimicry was first identified in tropical butterflies that shared colourful wing patterns, but it is found in many groups of insects such as bumblebees, and other animals including poison frogs and coral snakes. The mimicry need not be visual; for example, many snakes share auditory warning signals. Similarly, the defences involved are not limited to toxicity; anything that tends to deter predators, such as foul taste, sharp spines, or defensive behaviour can make a species unprofitable enough to predators to allow Müllerian mimicry to develop.
Once a pair of Müllerian mimics has formed, other mimics may join them by advergent evolution (one species changing to conform to the appearance of the pair, rather than mutual convergence), forming mimicry rings. Large rings are found for example in velvet ants. Since the frequency of mimics is negatively correlated with survivability, rarer mimics are likely to adapt to resemble commoner models, favouring both advergence and larger Müllerian mimicry rings. Where mimics are not strongly protected by venom or other defences, honest Müllerian mimicry grades into bluffing Batesian mimicry.Pseudocopulation
Pseudocopulation describes behaviors similar to copulation that serve a reproductive function for one or both participants but do not involve actual sexual union between the individuals. It is most generally applied to a pollinator attempting to copulate with a flower. Some flowers mimic a potential female mate visually, but the key stimuli are often chemical and tactile. This form of mimicry in plants is called Pouyannian mimicry.Orchids commonly achieve reproduction in this manner, secreting chemicals from glands (osmophores) in the sepals, petals, or labellum, that are indistinguishable from the insect's natural pheromones. The pollinator then has a pollinium attached to its body, which it transfers to the stigma of another flower when it attempts another 'copulation'. Pollinators are often bees, and wasps of the order Hymenoptera, and flies.
The cost to the pollinating insects might be seen as negligible, but study of Cryptostylis (an Australian orchid) pollinators shows that they may waste large amounts of sperm by ejaculating onto the flower. Thus there could be antagonistic coevolution such that pollinators become better at identifying their own species correctly and orchids become better mimics.
Pseudocopulation is also used to describe close physical contact between mating animals which have their eggs externally fertilized. Frogs provide one such case, with the male releasing sperm as the female discharges her eggs, a process called amplexus. In some species of starfish, a male and female may come together and form a pair. The male climbs on top, placing his arms between those of the female. When she releases eggs into the water, he is induced to release his sperm.Pseudocopulation is also used as a term to describe behaviours of birds that appear to be copulating but may merely involve mounting and could involve pairs of the same sex.Secret Chiefs 3
Secret Chiefs 3 (or SC3) is an avant-garde group led by guitarist/composer Trey Spruance (formerly of Mr. Bungle and Faith No More). Their studio recordings and tours have featured different line-ups, as the group performs a wide range of musical styles, mostly instrumental, including surf rock, Persian, Arab, Indian, death metal, film music, electronic music, and various others.
The band's name was inspired by the "Secret Chiefs" said to inspire and guide various esoteric and mystical groups, and is a reflection of Spruance's interest in such philosophies.Swallowtail butterfly
Swallowtail butterflies are large, colorful butterflies in the family Papilionidae, and include over 550 species. Though the majority are tropical, members of the family inhabit every continent except Antarctica. The family includes the largest butterflies in the world, the birdwing butterflies of the genus Ornithoptera.Swallowtails have a number of distinctive features; for example, the papilionid caterpillar bears a repugnatorial organ called the osmeterium on its prothorax. The osmeterium normally remains hidden, but when threatened, the larva turns it outward through a transverse dorsal groove by inflating it with fluid.The forked appearance of the swallowtails' hindwings, which can be seen when the butterfly is resting with its wings spread, gave rise to the common name swallowtail. As for its formal name, Linnaeus chose Papilio for the type genus, as papilio is Latin for "butterfly". For the specific epithets of the genus, Linnaeus applied the names of Greek figures to the swallowtails. The type species: Papilio machaon honored Machaon, one of the sons of Asclepius, mentioned in the Iliad. Further, the species Papilio homerus is named after the Greek poet, Homer.
Vision in animals
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