100-460: 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. In the simplest case, as in Batesian mimicry , a mimic resembles a model, so as to deceive a dupe, all three being of different species. A Batesian mimic, such as a hoverfly ,
200-456: 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,
300-418: 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
400-414: A deceptive distraction display to lure predators away from their flightless young: When a man comes by chance upon a young brood [of partridges], and tries to catch them, the hen-bird rolls in front of the hunter, pretending to be lame: the man every moment thinks he is on the point of catching her, and so she draws him on and on, until every one of her brood has had time to escape; hereupon she returns to
500-443: A deeper understanding of disease through evolutionary medicine and to develop evolutionary therapies . Evolution plays a role in resistance of drugs; for example, how HIV becomes resistant to medications and the body's immune system. The mutation of resistance of HIV is due to the natural selection of the survivors and their offspring. The few HIV that survive the immune system reproduced and had offspring that were also resistant to
600-413: A generation of evolutionary biologists. Current research in evolutionary biology covers diverse topics and incorporates ideas from diverse areas, such as molecular genetics and computer science . First, some fields of evolutionary research try to explain phenomena that were poorly accounted for in the modern evolutionary synthesis . These include speciation , the evolution of sexual reproduction ,
700-430: 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
800-404: A population. It has a much stronger effect on small populations than large ones. Gene flow : Gene flow is the transfer of genetic material from the gene pool of one population to another. In a population, migration occurs from one species to another, resulting in the change of allele frequency. Natural selection : The survival and reproductive rate of a species depends on the adaptability of
900-428: 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
1000-546: 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 . In Dodsonian mimicry, named after Calaway H. Dodson , the model belongs to a different species than the mimic. By resembling the model, a flower can lure its pollinators without offering nectar. The mechanism occurs in several orchids, including Epidendrum ibaguense which mimics flowers of Lantana camara and Asclepias curassavica , and
1100-459: 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. 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 ;
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#17328513421221200-499: Is honest , as when species of wasps and of bees all have genuinely aposematic warning coloration. 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. Mimicry is not limited to animals; in Pouyannian mimicry , an orchid flower
1300-412: Is a sheep in wolf's clothing . Mimics are less likely to be found out (for example by predators) when in low proportion to their model. Such negative frequency-dependent selection applies in most forms of mimicry. Specifically, 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
1400-496: Is a change in the DNA sequence inside a gene or a chromosome of an organism. Most mutations are deleterious, or neutral; i.e. they can neither harm nor benefit, but can also be beneficial sometimes. Genetic drift : Genetic drift is a variational process, it happens as a result of the sampling errors from one generation to another generation where a random event that happens by chance in nature changes or influences allele frequency within
1500-583: Is a combination of visual, by olfaction , and by touch. Vavilovian mimicry is found in weeds that come to share characteristics with a domesticated plant through unintentional 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 illustrates unintentional selection by man . Weeders do not want to select weeds and their seeds that look increasingly like cultivated plants, yet there
1600-441: 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 subfamily Danainae , which feed on milkweed species of varying toxicity. These species store toxins from its host plant, which are maintained even in
1700-412: Is also an example of resistance that will cause the bacteria against which the antibiotic is being taken to evolve and continue to spread in the body. When the full dosage of the medication does not enter the body and perform its proper job, the bacteria that survive the initial dosage will continue to reproduce. This can make for another bout of sickness later on that will be more difficult to cure because
1800-453: Is also prominent in the review journals Trends in Ecology and Evolution and Annual Review of Ecology, Evolution, and Systematics . The journals Genetics and PLoS Genetics overlap with molecular genetics questions that are not obviously evolutionary in nature. Heliconiinae and see text The Heliconiinae , commonly called heliconians or longwings , are a subfamily of
1900-956: Is by approaches, such as field biology, theoretical biology , experimental evolution , and paleontology. These alternative ways of dividing up the subject have been combined with evolutionary biology to create subfields like evolutionary ecology and evolutionary developmental biology . More recently, the merge between biological science and applied sciences gave birth to new fields that are extensions of evolutionary biology, including evolutionary robotics , engineering , algorithms , economics , and architecture. The basic mechanisms of evolution are applied directly or indirectly to come up with novel designs or solve problems that are difficult to solve otherwise. The research generated in these applied fields, contribute towards progress, especially from work on evolution in computer science and engineering fields such as mechanical engineering. Adaptive evolution relates to evolutionary changes that happen due to
2000-434: Is deceived to change its behaviour to the mimic's selective advantage. The resemblances can be via any sensory modality, including any combination of visual, acoustic, chemical, tactile, or electric. Mimicry may be to the advantage of both organisms that share a resemblance, in which case it is mutualistic ; or it can be to the detriment of one, making it parasitic or competitive . The evolutionary convergence between groups
2100-594: Is driven by the selective action of a dupe. Birds, for example, use sight to identify palatable insects, whilst avoiding noxious ones. Over time, palatable insects may evolve to resemble noxious ones, making them mimics and the noxious ones models. Models do not have to be more abundant than mimics. In the case of mutualism, each model is also a mimic; all such species can be called "co-mimics". Many harmless species such as hoverflies are Batesian mimics of strongly defended species such as wasps, while many such well-defended species form Müllerian mimicry rings of co-mimics. In
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#17328513421222200-407: Is harmless, while its model, such as a wasp , is harmful, and is avoided by the dupe, such as an insect-eating bird. Birds hunt by sight, so the mimicry in that case is visual, but in other cases mimicry may make use of any of the senses. Most types of mimicry, including Batesian, are deceptive, as the mimics are not harmful, but Müllerian mimicry , where different harmful species resemble each other,
2300-400: Is inherited through the female line in so-called gentes (gens, singular). Intraspecific brood parasitism, where a female lays in a conspecific's nest, as illustrated by the goldeneye duck ( Bucephala clangula ), do not involve mimicry The parasitic butterfly Phengaris rebeli parasitizes the ant species Myrmica schencki by releasing chemicals that fool the worker ants to believe that
2400-432: 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 . Inter-sexual mimicry (a type of automimicry, as it
2500-448: Is pollinated by monarch butterflies and perhaps hummingbirds . Brood parasitism or Kirbyan mimicry is a two species system where a brood parasite mimics its host. Cuckoos are a canonical example; the female cuckoo has its offspring raised by a bird of a different species, cutting down the biological mother's parental investment . The ability to lay eggs that mimic the host eggs is the key adaptation . The adaptation to different hosts
2600-437: Is that the classical population genetics that catalysed the modern evolutionary synthesis must be updated to take into account modern molecular knowledge. This requires a great deal of mathematical development to relate DNA sequence data to evolutionary theory as part of a theory of molecular evolution . For example, biologists try to infer which genes have been under strong selection by detecting selective sweeps . Fourth,
2700-473: Is the mimic, resembling a female bee, its model; the dupe is the male bee of the same species, which tries to copulate with the flower, enabling it to transfer pollen, so the mimicry is again bipolar. In automimicry , another bipolar system, model and mimic are the same, as when blue lycaenid butterflies have 'tails' or eyespots on their wings that mimic their own heads, misdirecting predator dupes to strike harmlessly. Many other types of mimicry exist. Use of
2800-507: Is the more worthy of notice since it occurs between insects both belonging to the group of butterflies which are protected by distastefulness. The explanation which applies in ordinary cases of [Batesian] mimicry—and no other has, so far as I know, been offered—cannot obtain for this imitation among protected species. 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
2900-520: Is the process in which related or distantly related organisms evolve similar characteristics independently. This type of evolution creates analogous structures which have a similar function, structure, or form between the two species. For example, sharks and dolphins look alike but they are not related. Likewise, birds, flying insects, and bats all have the ability to fly, but they are not related to each other. These similar traits tend to evolve from having similar environmental pressures. Divergent evolution
3000-428: Is the process of speciation. This can happen in several ways: The influence of two closely associated species is known as coevolution . When two or more species evolve in company with each other, one species adapts to changes in other species. This type of evolution often happens in species that have symbiotic relationships . For example, predator-prey coevolution, this is the most common type of co-evolution. In this,
3100-454: Is the subfield of biology that studies the evolutionary processes ( natural selection , common descent , speciation ) that produced the diversity of life on Earth. It is also defined as the study of the history of life forms on Earth. Evolution holds that all species are related and gradually change over generations. In a population, the genetic variations affect the phenotypes (physical characteristics) of an organism. These changes in
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3200-416: Is to mimic a mutualistic symbiont of the prey. Cleaner fish eat parasites and dead skin from client fish. Some allow the cleaner to venture inside their body to hunt these parasites. However, the sabre-toothed blenny or false cleanerfish ( Aspidontus taeniatus ) mimics the bluestreak cleaner wrasse ( Labroides dimidiatus ), which is recognized by other fishes as a cleaner. The false cleanerfish resembles
3300-466: Is unlike Müllerian mimicry, where the most harmful species 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. But if
3400-427: 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. 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
3500-420: 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
3600-429: Is within a single species) 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
3700-744: The Argynnini are quite diverse in the Holarctic . Especially tropical species feed on poisonous plants , characteristically Passifloraceae vines, as larvae , becoming poisonous themselves. The adult butterflies announce their acquired toxicity with strong aposematic colours, warning off would-be predators . There are several famous cases of Batesian and Müllerian mimicry both within this group and with other butterflies. Other commonly seen food plants are Fabaceae (which also contain several toxic species), and particularly among northerly species of Violaceae . Four or five tribes are generally recognized in
3800-882: The Heliconidae , without examining them closely after capture. The German naturalist Fritz Müller also spent many years studying butterflies in the Amazon rainforest. He first published a journal article on mimicry in German in 1878, followed in 1879 by a paper to the Entomological Society of London (translated and presented by Ralph Meldola). He described a situation where different species were each unpalatable to predators, and shared similar, genuine, warning signals. Bates found it hard to explain why this should be so, asking why they should need to mimic each other if both were harmful and could warn off predators on their own. Müller put forward
3900-581: The brush-footed butterflies ( family Nymphalidae). They can be divided into 45–50 genera and were sometimes treated as a separate family Heliconiidae within the Papilionoidea . The colouration is predominantly reddish and black, and though of varying wing shape, the forewings are always elongated tipwards, hence the common name. Most longwings are found in the Tropics , particularly in South America ; only
4000-421: The genetic architecture of adaptation , molecular evolution , and the different forces that contribute to evolution, such as sexual selection , genetic drift , and biogeography . Moreover, the newer field of evolutionary developmental biology ("evo-devo") investigates how embryogenesis is controlled, thus yielding a wider synthesis that integrates developmental biology with the fields of study covered by
4100-574: The lichens of the oak on which I took it. The spectre tribe ( Phasma ) go still further in this mimicry, representing a small branch with its spray. The English naturalist Henry Walter Bates worked for several years on butterflies in the Amazon rainforest . Returning home, he described multiple forms of mimicry in an 1862 paper at the Linnean Society in London, and then in his 1863 book The Naturalist on
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4200-550: The phenotypes will be an advantage to some organisms, which will then be passed on to their offspring . Some examples of evolution in species over many generations are the peppered moth and flightless birds . In the 1930s, the discipline of evolutionary biology emerged through what Julian Huxley called the modern synthesis of understanding, from previously unrelated fields of biological research, such as genetics and ecology, systematics , and paleontology . The investigational range of current research has widened to encompass
4300-442: The turkey vulture . It flies amongst the vultures, effectively camouflaged as a vulture which poses no threat to the hawk's prey. It hunts by suddenly breaking from the formation and ambushing its prey. Parasites can be aggressive mimics, though the situation is somewhat different from those outlined previously. They can mimic their hosts' natural prey, allowing themselves to be eaten as a pathway into their host. Leucochloridium ,
4400-472: The Heliconiinae. There have been numerous attempts to sort out the phylogenetic sequence and delimitation of these, but while the former has made good progress, the latter has hitherto only achieved limited results. Several phylogenies (and corresponding taxonomic adjustments) have been proposed, but though looking reasonable each and every one of them is only weakly supported. Even cladistic analyses of
4500-605: The Mesozoic and Cenozoic eras (between 299 million to 12,000 years ago). Other fields related to generic exploration of evolution ("what happened and when?" ) include systematics and phylogenetics . Third, the modern evolutionary synthesis was devised at a time when nobody understood the molecular basis of genes. Today, evolutionary biologists try to determine the genetic architecture of interesting evolutionary phenomena such as adaptation and speciation. They seek answers to questions such as how many genes are involved, how large are
4600-616: The River Amazons . 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. 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
4700-414: The adult. As levels of toxin vary depending on diet, some individuals are more toxic than the rest, which profit from the toxicity of those individuals, just as hoverflies benefit from mimicking well-defended wasps. One form of automimicry 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
4800-461: The apparent anomalies seem to sort themselves out at least for the most part. For example, the confusing distribution pattern of Acraea in the wide circumscription is apparently simply due to the bulk of this morphologically conservative group warranting recognition as genus Telchinia – it stands to note that this group has on occasion been allied with Actinote rather than Acraea , and this indeed appears to be correct. In addition,
4900-407: The back of the head, misleading predators into reacting as though they were the subject of an aggressive stare. 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 . Spectacular examples occur in the hairstreak butterflies; when perching on
5000-434: The bacteria involved will be resistant to the first medication used. Taking the full course of medicine that is prescribed is a vital step in avoiding antibiotic resistance. Individuals with chronic illnesses, especially those that can recur throughout a lifetime, are at greater risk of antibiotic resistance than others. This is because overuse of a drug or too high of a dosage can cause a patient's immune system to weaken and
5100-461: 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. 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
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#17328513421225200-444: The caterpillar larvae are ant larvae. This enables the larvae to be brought directly into the ant's nest. In Pouyannian mimicry, a flower mimics a female of a certain insect species, inducing the males of that species to try to copulate with the flower. This is much like aggressive mimicry in fireflies, but with a more benign outcome for the pollinator. The mechanism is named after Maurice-Alexandre Pouyanne , who first described
5300-500: The changes in the environment, this makes the organism suitable to its habitat. This change increases the chances of survival and reproduction of the organism (this can be referred to as an organism's fitness ). For example, Darwin's Finches on Galapagos island developed different shaped beaks in order to survive for a long time. Adaptive evolution can also be convergent evolution if two distantly related species live in similar environments facing similar pressures. Convergent evolution
5400-401: The cleaner, and mimics the cleaner's "dance". Once it is allowed close to the client, it attacks, biting off a piece of its fin before fleeing. Fish wounded in this fashion soon learn to distinguish mimic from model, but because the similarity is close they also become much more cautious of the model. A mechanism that does not involve any luring is seen in the zone-tailed hawk , which resembles
5500-425: The earlier evolutionary synthesis. Evolution is the central unifying concept in biology. Biology can be divided into various ways. One way is by the level of biological organization , from molecular to cell , organism to population . Another way is by perceived taxonomic group , with fields such as zoology , botany , and microbiology , reflecting what was once seen as the major divisions of life. A third way
5600-454: The effects of each gene, how interdependent are the effects of different genes, what do the genes do, and what changes happen to them (e.g., point mutations vs. gene duplication or even genome duplication ). They try to reconcile the high heritability seen in twin studies with the difficulty in finding which genes are responsible for this heritability using genome-wide association studies . One challenge in studying genetic architecture
5700-409: The evolution of cooperation , the evolution of ageing , and evolvability . Second, some evolutionary biologists ask the most straightforward evolutionary question: "what happened and when?". This includes fields such as paleobiology , where paleobiologists and evolutionary biologists, including Thomas Halliday and Anjali Goswami, studied the evolution of early mammals going far back in time during
5800-401: The evolution of wasp-like appearance, it has been argued that insects evolve to masquerade wasps since predatory wasps do not attack each other, and that this mimetic resemblance has had the useful side-effect of deterring vertebrate predators. Mimicry can result in an evolutionary arms race if mimicry negatively affects the model, in which case the model can evolve a different appearance from
5900-429: The exact placement of each respective to the other tribes cannot be considered well resolved at all. Some tribes are distributed among several continents , resulting in a confusing phylogeography pattern. But as it seems, the apparent contradictions between systematics and biogeography are due to the premature classifications based on insufficient taxon sampling. With studies becoming more and more comprehensive,
6000-433: The first mathematical model of mimicry for this phenomenon: if a common predator confuses the two species, individuals in both those species are more likely to survive, as fewer individuals of either species are killed by the predator. The term Müllerian mimicry , named in his honour, has since been used for this mutualistic form of mimicry. Müller wrote that The resemblance of the genera named [ Ituna and Thyridia ]
6100-803: The genus Pardopsis , often placed in the Acraeini, does almost certainly not belong there; it is now tentatively placed in the Argynnini. The relationships of the genus Cethosia (sometimes treated as a tribe of its own) are even more mysterious, and it is likely that some other genera will eventually also be moved to a different tribe as they are studied in detail. Some, like the Argynnini Argynnis , Boloria and Issoria , might be overlumped and non- monophyletic and thus some genera presently usually considered junior synonyms of them might eventually be validated like Telchinia . Genera are presented in
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#17328513421226200-583: 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 D. galeatus . Batesian mimicry occurs in
6300-445: The illness will evolve and grow stronger. For example, cancer patients will need a stronger and stronger dosage of medication because of their low functioning immune system. Some scientific journals specialise exclusively in evolutionary biology as a whole, including the journals Evolution , Journal of Evolutionary Biology , and BMC Evolutionary Biology . Some journals cover sub-specialties within evolutionary biology, such as
6400-435: The immune system. Drug resistance also causes many problems for patients such as a worsening sickness or the sickness can mutate into something that can no longer be cured with medication. Without the proper medicine, a sickness can be the death of a patient. If their body has resistance to a certain number of drugs, then the right medicine will be harder and harder to find. Not completing the prescribed full course of antibiotic
6500-535: The journals Systematic Biology , Molecular Biology and Evolution and its sister journal Genome Biology and Evolution , and Cladistics . Other journals combine aspects of evolutionary biology with other related fields. For example, Molecular Ecology , Proceedings of the Royal Society of London Series B , The American Naturalist and Theoretical Population Biology have overlap with ecology and other aspects of organismal biology. Overlap with ecology
6600-486: The kind of worm itself. Other structures like the development of Hox genes and sensory organs such as eyes can also be traced with this practice. Phylogenetic Trees are representations of genetic lineage. They are figures that show how related species are to one another. They formed by analyzing the physical traits as well as the similarities of the DNA between species. Then by using a molecular clock scientists can estimate when
6700-444: The mating signals of females of the genus Photinus . Male fireflies from several different genera are attracted to these " femmes fatales ", and are captured and eaten. Each female has a repertoire of signals matching the delay and duration of the flashes of the female of the corresponding species. Some carnivorous plants may be able to increase their rate of capturing insect prey through mimicry. A different aggressive strategy
6800-414: The milk snakes and the deadly coral snakes are mimics, while the false coral snakes are the model. In Wasmannian mimicry , the mimic resembles a model that it lives along with in a nest or colony. Most of the models here are eusocial insects, principally ants. Gilbertian mimicry is bipolar, involving only two species. The potential host (or prey) drives away its parasite (or predator) by mimicking it,
6900-416: 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 has been debated, as classifications have differed or overlapped; attempts to clarify definitions have led to
7000-415: The mimic and the model benefit from the interaction, which could thus be classified as mutualism . 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. The distinction between mimic and model that is clear in Batesian mimicry is also blurred. Where one species is scarce and another abundant,
7100-404: The mimic is sufficiently protected. Convergent evolution is an alternative explanation for why coral reef fish have come to resemble each other; the same applies to benthic marine invertebrates such as sponges and nudibranchs . In its broadest definition, mimicry can include non-living models. The specific terms masquerade and mimesis are sometimes used when the models are inanimate, and
7200-514: The mimic. Mimics may have different models for different life cycle stages, or they may be polymorphic , with different individuals imitating different models, as occurs in Heliconius butterflies. Models tend to be relatively closely related to their mimics, but mimicry can be of vastly different species, for example when spiders mimic ants. Most known mimics are insects, though many other examples including vertebrates , plants, and fungi exist. It
7300-420: The mimicry's purpose is crypsis . 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. The model
7400-425: 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. Batesian systems are therefore most likely to be stable where
7500-412: The model is more abundant than the mimic. There are many Batesian mimics among butterflies and moths . Consul fabius and Eresia eunice imitate unpalatable Heliconius butterflies such as H. ismenius . Limenitis arthemis imitate the poisonous pipevine swallowtail ( Battus philenor ). Several palatable moths produce ultrasonic click calls to mimic unpalatable tiger moths. Octopuses of
7600-479: The modern discipline of evolutionary biology. Theodosius Dobzhansky and E. B. Ford established an empirical research programme. Ronald Fisher , Sewall Wright , and J. B. S. Haldane created a sound theoretical framework. Ernst Mayr in systematics , George Gaylord Simpson in paleontology and G. Ledyard Stebbins in botany helped to form the modern synthesis. James Crow , Richard Lewontin , Dan Hartl , Marcus Feldman , and Brian Charlesworth trained
7700-895: The modern evolutionary synthesis involved agreement about which forces contribute to evolution, but not about their relative importance. Current research seeks to determine this. Evolutionary forces include natural selection , sexual selection , genetic drift , genetic draft , developmental constraints, mutation bias and biogeography . This evolutionary approach is key to much current research in organismal biology and ecology, such as life history theory . Annotation of genes and their function relies heavily on comparative approaches. The field of evolutionary developmental biology ("evo-devo") investigates how developmental processes work, and compares them in different organisms to determine how they evolved. Many physicians do not have enough background in evolutionary biology, making it difficult to use it in modern medicine. However, there are efforts to gain
7800-409: The nest and calls the young back. The behaviour is recognised as a form of mimicry by biologists. In 1823, Kirby and Spence, in their book An Introduction to Entomology , used the term "mimicry" informally to depict the way that the structure and coloration of some insects resembled objects in their environments: A jumping bug, very similar to the one figured by Schellenberg , also much resembles
7900-407: The older departments of botany and zoology . Palaeontology is often grouped with earth science . Microbiology too is becoming an evolutionary discipline now that microbial physiology and genomics are better understood. The quick generation time of bacteria and viruses such as bacteriophages makes it possible to explore evolutionary questions. Many biologists have contributed to shaping
8000-408: The partial replacement of old terms with new ones. Mimicry is defensive or protective when organisms are able to avoid harmful encounters by deceiving enemies into treating them as something else. 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). In other words, a Batesian mimic
8100-399: 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. 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. Female fireflies of the genus Photuris emit light signals that mimic
8200-421: 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 pollinium 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. The mimicry
8300-432: The phylogenetic process is what allows for this kind of understanding of biology to be possible. By looking at different processes during development, and going through the evolutionary tree, one can determine at which point a specific structure came about. For example, the three germ layers can be observed to not be present in cnidarians and ctenophores, which instead present in worms, being more or less developed depending on
8400-454: The plant kingdom, where the chameleon vine adapts its leaf shape and colour to match that of the plant it is climbing. 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. This type of mimicry is unique in several respects. Firstly, both
8500-503: The point of hatching. The butterflies avoid laying eggs near existing ones, reducing intraspecific competition between caterpillars, which are also cannibalistic , so those that lay on vacant leaves provide their offspring with a greater chance of survival. The stipules thus appear to have evolved as Gilbertian mimics of butterfly eggs, under selection pressure from these caterpillars. Browerian mimicry, named after Lincoln P. Brower and Jane Van Zandt Brower who first described it in 1967,
8600-406: The predator first learnt to avoid a less deadly warning-coloured snake, the deadly species could profit by mimicking the less dangerous snake. Some harmless milk snakes ( Lampropeltis triangulum ), the moderately toxic false coral snakes ( Erythrolamprus aesculapii ), and the deadly coral snakes ( Micrurus ) all have a red background color with black and white/yellow rings. In this system, both
8700-579: The predator must evolve to become a more effective hunter because there is a selective pressure on the prey to steer clear of capture. The prey in turn need to develop better survival strategies. The Red Queen hypothesis is an example of predator-prey interations. The relationship between pollinating insects like bees and flowering plants, herbivores and plants, are also some common examples of diffuse or guild coevolution. The mechanisms of evolution focus mainly on mutation, genetic drift, gene flow, non-random mating, and natural selection. Mutation : Mutation
8800-435: 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
8900-432: The rare species can be said to be the mimic. 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. 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
9000-505: 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 who described it in 1975. The classical instance of Gilbertian mimicry is in the plant genus Passiflora , which is grazed by the micropredator larvae of some Heliconius butterflies. The host plants have evolved stipules that mimic mature Heliconius eggs near
9100-433: The same species. Often, mimicry functions to protect from predators . Mimicry systems have three basic roles: a mimic, a model, and a dupe. When these correspond to three separate species, the system is called disjunct; when the roles are taken by just two species, the system is called bipolar. Mimicry evolves if a dupe (such as a predator) perceives a mimic (such as a palatable prey) as a model (the organism it resembles), and
9200-422: The same type of data often yield contradicting results depending on the exact method of evaluation. Ultimately, the reason is that just a fraction of the evolutionary diversity of Heliconiinae has been sampled. What appears fairly certain is that the Argynnini and Vagrantini are closer relatives than any other two tribes of Heliconiinae. The Acraeini and Heliconiini are probably more basal lineages, but
9300-462: 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
9400-652: 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. Evolutionary biology Evolutionary biology
9500-420: The species diverged. An example of a phylogeny would be the tree of life. Genes that have shared ancestry are homologs. If a speciation event occurs and one gene ends up in two different species the genes are now orthologous. If a gene is duplicated within the a singular species then it is a paralog. A molecular clock can be used to estimate when these events occurred. The idea of evolution by natural selection
9600-468: The species to their environment. This process is called natural selection . Some species with certain traits in a population have higher survival and reproductive rate than others ( fitness ), and they pass on these genetic features to their offsprings. In evolutionary developmental biology, scientists look at how the different processes in development play a role in how a specific organism reaches its current body plan. The genetic regulation of ontogeny and
9700-448: The strategy resembles a wolf in sheep's clothing , though no conscious deceptive intent is involved. The mimic may resemble the prey or host itself, or another organism that does not threaten the prey or host. Several spiders use aggressive mimicry to lure prey. 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
9800-502: The unusual case where a deadly prey mimics a less dangerous species. It was first proposed by M. G. Emsley in 1966 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
9900-527: 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". "Mimicry" was first used in zoology by the English entomologists William Kirby and William Spence in 1823. Originally used to describe people, "mimetic" was used in zoology from 1851. Aristotle wrote in his History of Animals that partridges use
10000-485: Was proposed by Charles Darwin in 1859, but evolutionary biology, as an academic discipline in its own right, emerged during the period of the modern synthesis in the 1930s and 1940s. It was not until the 1980s that many universities had departments of evolutionary biology. In the United States, many universities have created departments of molecular and cell biology or ecology and evolutionary biology , in place of
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