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Peripatric speciation is a mode of
speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution withi ...
in which a new
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
is formed from an isolated peripheral population. Since peripatric speciation resembles
allopatric speciation Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
, in that populations are isolated and prevented from exchanging genes, it can often be difficult to distinguish between them. Nevertheless, the primary characteristic of peripatric speciation proposes that one of the populations is much smaller than the other. The terms peripatric and peripatry are often used in
biogeography Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...
, referring to
organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells ( cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fu ...
s whose ranges are closely adjacent but do not overlap, being separated where these organisms do not occur—for example on an oceanic island compared to the mainland. Such organisms are usually closely related (''e.g.'' sister species); their distribution being the result of peripatric speciation. The concept of peripatric speciation was first outlined by the evolutionary biologist
Ernst Mayr Ernst Walter Mayr (; 5 July 1904 – 3 February 2005) was one of the 20th century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, philosopher of biology, and historian of science. His ...
in 1954.Ernst Mayr. (1954). Change of genetic environment and evolution. In J. Huxley, A. C. Hardy & E. B. Ford. (eds) ''Evolution as a Process'', Unwin Brothers, London. Pp. 157–180. Since then, other alternative models have been developed such as centrifugal speciation, that posits that a species' population experiences periods of geographic
range expansion Colonisation or colonization is the process in biology by which a species spreads to new areas. Colonisation often refers to ''successful'' immigration where a population becomes integrated into an ecological community, having resisted initia ...
followed by shrinking periods, leaving behind small isolated populations on the periphery of the main population. Other models have involved the effects of
sexual selection Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (in ...
on limited population sizes. Other related models of peripherally isolated populations based on chromosomal rearrangements have been developed such as budding speciation and quantum speciation. The existence of peripatric speciation is supported by observational evidence and laboratory experiments. Scientists observing the patterns of a species biogeographic distribution and its
phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups ...
relationships are able to reconstruct the historical process by which they diverged. Further, oceanic islands are often the subject of peripatric speciation research due to their isolated habitats—with the
Hawaiian Islands The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost ...
widely represented in much of the scientific literature.


History

Peripatric speciation was originally proposed by
Ernst Mayr Ernst Walter Mayr (; 5 July 1904 – 3 February 2005) was one of the 20th century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, philosopher of biology, and historian of science. His ...
in 1954, and fully theoretically modeled in 1982. It is related to the
founder effect In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1942, us ...
, where small living populations may undergo selection bottlenecks. The founder effect is based on models that suggest peripatric speciation can occur by the interaction of selection and
genetic drift Genetic drift, also known as allelic drift or the Wright effect, is the change in the frequency of an existing gene variant (allele) in a population due to random chance. Genetic drift may cause gene variants to disappear completely and there ...
, which may play a significant role. Mayr first conceived of the idea by his observations of
kingfisher Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly colored birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species found in the tropical regions of Africa, Asia, and Oceania, ...
populations in New Guinea and its surrounding islands. '' Tanysiptera galatea'' was largely uniform in morphology on the mainland, but the populations on the surrounding islands differed significantly—referring to this pattern as "peripatric". This same pattern was observed by many of Mayr's contemporaries at the time such as by E. B. Ford's studies of ''
Maniola jurtina The meadow brown (''Maniola jurtina'') is a butterfly found in the Palearctic realm. Its range includes Europe south of 62°N, Russia eastwards to the Urals, Asia Minor, Iraq, Iran, North Africa and the Canary Islands. The larvae feed on g ...
''. Around the same time, the botanist
Verne Grant Verne Edwin Grant (1917-2007) was an American botanist and writer. Grant was born in San Francisco, California. In 1940 he received his BA in Botany and in 1949 his PhD in Botany and Genetics from the University of California, Berkeley. He was the ...
developed a model of quantum speciation very similar to Mayr's model in the context of plants. In what has been called Mayr's genetic revolutions, he postulated that genetic drift played the primary role that resulted in this pattern. Seeing that a species cohesion is maintained by conservative forces such as
epistasis Epistasis is a phenomenon in genetics in which the effect of a gene mutation is dependent on the presence or absence of mutations in one or more other genes, respectively termed modifier genes. In other words, the effect of the mutation is dep ...
and the slow pace of the spread of favorable alleles in a large population (based heavily on
J. B. S. Haldane John Burdon Sanderson Haldane (; 5 November 18921 December 1964), nicknamed "Jack" or "JBS", was a British-Indian scientist who worked in physiology, genetics, evolutionary biology, and mathematics. With innovative use of statistics in biolo ...
's calculations), he reasoned that speciation could only take place in which a
population bottleneck A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as specicide, widespread violen ...
occurred. A small, isolated, founder population could be established on an island for example. Containing less genetic variation from the main population, shifts in allele frequencies may occur from different selection pressures. This to further changes in the network of linked loci, driving a cascade of genetic change, or a "genetic revolution"—a large-scale reorganization of the entire genome of the peripheral population. Mayr did recognize that the chances of success were incredibly low and that extinction was likely; though noting that some examples of successful founder populations existed at the time. Shortly after Mayr, William Louis Brown, Jr. proposed an alternative model of peripatric speciation in 1957 called centrifugal speciation. In 1976 and 1980, the Kaneshiro model of peripatric speciation was developed by
Kenneth Y. Kaneshiro Kenneth is an English given name and surname. The name is an Anglicised form of two entirely different Gaelic personal names: ''Cainnech'' and '' Cináed''. The modern Gaelic form of ''Cainnech'' is ''Coinneach''; the name was derived from a b ...
which focused on sexual selection as a driver for speciation during population bottlenecks.


Models


Peripatric

Peripatric speciation models are identical to models of
vicariance Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
(allopatric speciation). Requiring both geographic separation and time, speciation can result as a predictable byproduct. Peripatry can be distinguished from allopatric speciation by three key features: *The size of the isolated population *Strong selection caused by the dispersal and colonization of novel environments, *The effects of
genetic drift Genetic drift, also known as allelic drift or the Wright effect, is the change in the frequency of an existing gene variant (allele) in a population due to random chance. Genetic drift may cause gene variants to disappear completely and there ...
on small populations. The size of a population is important because individuals colonizing a new habitat likely contain only a small sample of the genetic variation of the original population. This promotes divergence due to strong selective pressures, leading to the rapid fixation of an
allele An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chrom ...
within the descendant population. This gives rise to the potential for genetic incompatibilities to evolve. These incompatibilities cause
reproductive isolation The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offsprin ...
, giving rise to—sometimes rapid—speciation events. Furthermore, two important predictions are invoked, namely that geological or climatic changes cause populations to become locally fragmented (or regionally when considering allopatric speciation), and that an isolated population's reproductive traits evolve enough as to prevent interbreeding upon potential
secondary contact Secondary contact is the process in which two allopatricaly distributed populations of a species are geographically reunited. This contact allows for the potential for the exchange of genes, dependent on how reproductively isolated the two popula ...
. The peripatric model results in, what have been called, progenitor-derivative species pairs, whereby the derivative species (the peripherally isolated population)—geographically and genetically isolated from the progenitor species—diverges. A specific
phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups ...
signature results from this mode of speciation: the geographically widespread progenitor species becomes
paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...
(thereby becoming a
paraspecies A paraspecies (a paraphyletic species) is a species, living or fossil, that gave rise to one or more daughter species without itself becoming extinct. Geographically widespread species that have given rise to one or more daughter species as periphe ...
), with respect to the derivative species (the peripheral isolate). The concept of a paraspecies is therefore a logical consequence of the evolutionary species concept, by which one species gives rise to a daughter species. It is thought that the character traits of the peripherally isolated species become
apomorphic In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...
, while the central population remains pleisomorphic. Modern cladistic methods have developed definitions that have incidentally removed derivative species by defining clades in a way that assumes that when a speciation event occurs, the original species no longer exists, while two new species arise; this is not the case in peripatric speciation. Mayr warned against this, as it causes a species to lose their classification status. Loren H. Rieseberg and Luc Brouillet recognized the same dilemma in plant classification.


Quantum and budding speciation

The botanist Verne Grant proposed the term quantum speciation that combined the ideas of J. T. Gulick (his observation of the variation of species in semi-isolation),
Sewall Wright Sewall Green Wright FRS(For) Honorary FRSE (December 21, 1889March 3, 1988) was an American geneticist known for his influential work on evolutionary theory and also for his work on path analysis. He was a founder of population genetics alongsi ...
(his models of genetic drift), Mayr (both his peripatric and genetic revolution models), and George Gaylord Simpson (his development of the idea of quantum evolution). Quantum speciation is a rapid process with large genotypic or phenotypic effects, whereby a new, cross-fertilizing plant species buds off from a larger population as a semi-isolated peripheral population. Interbreeding and genetic drift takes place due to the reduced population size, driving changes to the genome that would most likely result in extinction (due to low adaptive value). In rare instances, chromosomal traits with adaptive value may arise, resulting in the origin of a new, derivative species. Evidence for the occurrence of this type of speciation has been found in several plant species pairs: ''
Layia discoidea ''Layia discoidea'' is a rare species of flowering plant in the family Asteraceae known by the common name rayless tidytips, or rayless layia. Distribution ''Layia discoidea'' is a local serpentine endemic where it is known only from the Diablo ...
'' and '' L. glandulosa'', ''
Clarkia lingulata ''Clarkia lingulata'' is a rare species of wildflower known by the common name Merced clarkia. This plant is endemic to Mariposa County, California, where it is known from only two sites near the Merced River. It is thought to have evolved very ...
'' and '' C. biloba'', and ''
Stephanomeria malheurensis ''Stephanomeria malheurensis'', the Malheur wirelettuce, is a species of flowering plant in the family Asteraceae. It is endemic to Oregon in the United States. It is a federally listed endangered species. It was discovered in 1966 and the pop ...
'' and ''S. exigua'' ssp. ''coronaria''. A closely related model of peripatric speciation is called budding speciation—largely applied in the context of plant speciation. The budding process, where a new species originates at the margins of an ancestral range, is thought to be common in plants—especially in progenitor-derivative species pairs.


Centrifugal speciation

William Louis Brown, Jr. proposed an alternative model of peripatric speciation in 1957 called centrifugal speciation. This model contrasts with peripatric speciation by virtue of the origin of the genetic novelty that leads to reproductive isolation. A population of a species experiences periods of geographic range expansion followed by periods of contraction. During the contraction phase, fragments of the population become isolated as small refugial populations on the periphery of the central population. Because of the large size and potentially greater genetic variation within the central population,
mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, m ...
s arise more readily. These mutations are left in the isolated peripheral populations, promoting reproductive isolation. Consequently, Brown suggested that during another expansion phase, the central population would overwhelm the peripheral populations, hindering speciation. However, if the species finds a specialized ecological niche, the two may coexist. The phylogenetic signature of this model is that the central population becomes
derived Derive may refer to: *Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguation ...
, while the peripheral isolates stay pleisomorphic—the reverse of the general model. In contrast to centrifugal speciation, peripatric speciation has sometimes been referred to as centripetal speciation (see figures 1 and 2 for a contrast). Centrifugal speciation has been largely ignored in the scientific literature, often dominated by the traditional model of peripatric speciation. Despite this, Brown cited a wealth of evidence to support his model, of which has not yet been refuted. ''
Peromyscus ''Peromyscus'' is a genus of rodents. They are commonly referred to as deer mice or deermice, not to be confused with the chevrotain or "mouse deer". They are New World mice only distantly related to the common house and laboratory mouse, '' ...
polionotus'' and ''P. melanotis'' (the peripherally isolated species from the central population of ''P. maniculatus'') arose via the centrifugal speciation model. Centrifugal speciation may have taken place in
tree kangaroo Tree-kangaroos are marsupials of the genus ''Dendrolagus'', adapted for arboreal locomotion. They inhabit the tropical rainforests of New Guinea and far northeastern Queensland, along with some of the islands in the region. All tree-kangaroos a ...
s, South American frogs (''
Ceratophrys ''Ceratophrys'' is a genus of frogs in the family Ceratophryidae. They are also known as South American horned frogs as well as Pacman frogs due to their characteristic round shape and large mouth, reminiscent of the video game character Pac-Man ...
''), shrews ('' Crocidura''), and primates ('' Presbytis melalophos'').
John C. Briggs John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second E ...
associates centrifugal speciation with centers of origin, contending that the centrifugal model is better supported by the data, citing species patterns from the proposed 'center of origin' within the Indo-West Pacific


Kaneshiro model

When a sexual species experiences a population bottleneck—that is, when the genetic variation is reduced due to small population size— mating discrimination among females may be altered by the decrease in courtship behaviors of males. Sexual selection pressures may become weakened by this in an isolated peripheral population, and as a by-product of the altered mating recognition system, secondary sexual traits may appear. Eventually, a growth in population size paired with novel female mate preferences will give rise to reproductive isolation from the main population-thereby completing the peripatric speciation process. Support for this model comes from experiments and observation of species that exhibit asymmetric mating patterns such as the Hawaiian ''Drosophila'' species or the Hawaiian cricket ''
Laupala ''Laupala'' is a genus of crickets belonging to the family Trigonidiidae. Species: *'' Laupala cerasina'' *'' Laupala eukolea'' *'' Laupala eupacifica'' *'' Laupala fugax'' *'' Laupala hapapa'' *'' Laupala hualalai'' *'' Laupala kai'' ...
''. However, this model has not been entirely supported by experiments, and therefore, it may not represent a plausible process of peripatric speciation that takes place in nature.


Evidence

Observational evidence and laboratory experiments support the occurrence of peripatric speciation.
Island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An isla ...
s and
archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Arch ...
s are often the subject of speciation studies in that they represent isolated populations of organisms. Island species provide direct evidence of speciation occurring peripatrically in such that, "the presence of
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
species on oceanic islands whose closest relatives inhabit a nearby
continent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...
" must have originated by a colonization event. Comparative phylogeography of oceanic
archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Arch ...
s shows consistent patterns of sequential colonization and speciation along island chains, most notably on the
Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...
islands,
Canary Islands The Canary Islands (; es, :es:Canarias, Canarias, ), also known informally as the Canaries, are a Spanish Autonomous communities of Spain, autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to ...
,
Society Islands The Society Islands (french: Îles de la Société, officially ''Archipel de la Société;'' ty, Tōtaiete mā) are an archipelago located in the South Pacific Ocean. Politically, they are part of French Polynesia, an overseas country of the F ...
,
Marquesas Islands The Marquesas Islands (; french: Îles Marquises or ' or '; Marquesan: ' (North Marquesan) and ' ( South Marquesan), both meaning "the land of men") are a group of volcanic islands in French Polynesia, an overseas collectivity of France in ...
,
Galápagos Islands The Galápagos Islands ( Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuad ...
,
Austral Islands The Austral Islands (french: Îles Australes, officially ''Archipel des Australes;'' ty, Tuha'a Pae) are the southernmost group of islands in French Polynesia, an overseas country of the French Republic in the South Pacific. Geographically, t ...
, and the Hawaiian Islands—all of which express geological patterns of spatial isolation and, in some cases, linear arrangement. Peripatric speciation also occurs on continents, as isolation of small populations can occur through various geographic and
dispersion Dispersion may refer to: Economics and finance *Dispersion (finance), a measure for the statistical distribution of portfolio returns *Price dispersion, a variation in prices across sellers of the same item *Wage dispersion, the amount of variatio ...
events. Laboratory studies have been conducted where populations of ''
Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many speci ...
'', for example, are separated from one another and evolve in reproductive isolation.


Hawaiian archipelago

''
Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many speci ...
'' species on the
Hawaiian archipelago The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost K ...
have helped researchers understand speciation processes in great detail. It is well established that ''Drosophila'' has undergone an
adaptive radiation In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic in ...
into hundreds of endemic species on the Hawaiian island chain; originating from a single common ancestor (supported from molecular analysis). Studies consistently find that colonization of each island occurred from older to younger islands, and in ''Drosophila'', speciating peripatrically at least fifty percent of the time. In conjunction with ''Drosophila'', Hawaiian lobeliads ('' Cyanea'') have also undergone an adaptive radiation, with upwards of twenty-seven percent of
extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...
species arising after new island colonization—exemplifying peripatric speciation—once again, occurring in the old-to-young island direction. Other endemic species in Hawaii also provide evidence of peripatric speciation such as the endemic flightless crickets (''
Laupala ''Laupala'' is a genus of crickets belonging to the family Trigonidiidae. Species: *'' Laupala cerasina'' *'' Laupala eukolea'' *'' Laupala eupacifica'' *'' Laupala fugax'' *'' Laupala hapapa'' *'' Laupala hualalai'' *'' Laupala kai'' ...
''). It has been estimated that, "17 species out of 36 well-studied cases of 'Laupala''speciation were peripatric". Plant species in genera's such as ''
Dubautia ''Dubautia'' is a genus of flowering plant in the family Asteraceae. The genus was named after Joseph Eugène DuBaut (1796-1832), an officer in the French Navy who participated in Freycinet's expedition. The entire genus is endemic to Hawaii. I ...
'', '' Wilkesia'', and ''
Argyroxiphium ''Argyroxiphium'' is a small genus of plants in the family Asteraceae. Its members are known by the common names silversword or greensword due to their long, narrow leaves and the silvery hairs on some species. The silverswords belong to a larger ...
'' have also radiated along the archipelago. Other animals besides insects show this same pattern such as the Hawaiian amber snail (''
Succinea caduca ''Succinea'', common name the amber snails, is a large genus of small, air-breathing land snails, terrestrial pulmonate gastropod molluscs in the family Succineidae. MolluscaBase eds. (2021). MolluscaBase. Succinea Draparnaud, 1801. Acces ...
''), and ‘Elepaio flycatchers. ''
Tetragnatha ''Tetragnatha'' is a genus of long-jawed orb-weavers found all over the world. It was first described by Pierre André Latreille in 1804, and it contains hundreds of species. Most occur in the tropics and subtropics, and many can run over wat ...
'' spiders have also speciated peripatrically on the Hawaiian islands, Numerous arthropods have been documented existing in patterns consistent with the geologic evolution of the island chain, in such that, phylogenetic reconstructions find younger species inhabiting the geologically younger islands and older species inhabiting the older islands (or in some cases, ancestors date back to when islands currently below sea level were exposed). Spiders such as those from the genus ''
Orsonwelles ''Orsonwelles'' is a genus of American dwarf spiders that was first described by G. Hormiga in 2002. They are all native to the Hawaiian Islands, each species occurring on a single island, often at high elevations. One species has not been coll ...
'' exhibit patterns compatible with the old-to-young geology. Other endemic genera such as '' Argyrodes'' have been shown to have speciated along the island chain. ''
Pagiopalus ''Pagiopalus'' is a genus of Hawaiian running crab spiders that was first described by Eugène Louis Simon in 1900. Species it contains four species, found only on Hawaii: *'' Pagiopalus apiculus'' Suman, 1971 – Hawaii *'' Pagiopalus atomari ...
'', '' Pedinopistha'', and part of the family
Thomisidae The Thomisidae are a family of spiders, including about 170 genera and over 2,100 species. The common name crab spider is often linked to species in this family, but is also applied loosely to many other families of spiders. Many members of th ...
have adaptively radiated along the island chain, as well as the wolf spider family, Lycosidae. A host of other Hawaiian endemic arthropod species and genera have had their speciation and phylogeographical patterns studied: the ''
Drosophila grimshawi ''Drosophila grimshawi'' is a species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of ...
'' species complex,
damselflies Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, Anisoptera, but are smaller and have slimmer bodies. Most species fold the wings alo ...
(''
Megalagrion ''Megalagrion'' is a genus of damselflies in the family Coenagrionidae. It contains approximately 26 species, all of which are endemic to Hawaii. Megalagrion damselflies are the only native damselflies in Hawaii, and are referred to as " pinapi ...
xanthomelas'' and ''Megalagrion pacificum''), ''
Doryonychus raptor ''Doryonychus'' is a monotypic genus of Hawaiian long-jawed orb-weavers containing the single species, ''Doryonychus raptor''. It was first described by Eugène Louis Simon in 1900, and is known only from the Hawaiian island of Kauai. See a ...
'', ''
Littorophiloscia hawaiiensis ''Littorophiloscia'' is a genus of woodlice A woodlouse (plural woodlice) is an isopod crustacean from the polyphyleticThe current consensus is that Oniscidea is actually triphyletic suborder Oniscidea within the order Isopoda. They get ...
'', ''
Anax strenuus The giant Hawaiian darner, also known as the giant Hawaiian dragonfly or pinao (''Anax strenuus''), is a species of dragonfly in the family Aeshnidae. It is one of two species of dragonfly that is endemic to the Hawaiian Islands The Hawaii ...
'', '' Nesogonia blackburni'', '' Theridion grallator'', ''
Vanessa tameamea Vanessa may refer to: Arts and entertainment * ''Vanessa'' (Millais painting), an 1868 painting by Pre-Raphaelite artist John Everett Millais * ''Vanessa'', a 1933 novel by Hugh Walpole * ''Vanessa'', a 1952 instrumental song written by Bernie ...
'', '' Hyalopeplus pellucidus'', ''
Coleotichus blackburniae ''Coleotichus blackburniae'' is a species of insect in the family Scutelleridae, the jewel bugs. It is commonly known as the Koa bug or the Koa shield bug. It has been dubbed the stinkless stink bug for its lack of the malodorous defensive chemi ...
'', '' Labula'', ''
Hawaiioscia ''Hawaiioscia'' is a genus of woodlouse known from the Hawaii, Rapa Nui, and Costa Rica. The genus was originally described from Hawaii on the presence of four troglobitic species on separate islands. A species within this genus was then desc ...
'', '' Banza'' (in the family
Tettigoniidae Insects in the family Tettigoniidae are commonly called katydids (especially in North America), or bush crickets. They have previously been known as "long-horned grasshoppers". More than 8,000 species are known. Part of the suborder Ensifera, ...
), ''
Caconemobius ''Caconemobius'' is a genus of crickets in the subfamily Nemobiinae. There are about 15 species distributed from the Pacific coasts of Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a ...
'', '' Eupethicea'', ''
Ptycta ''Ptycta'' is a genus of common barklice in the family Psocidae. There are more than 150 described species in ''Ptycta''. See also * List of Ptycta species References Psocidae Articles created by Qbugbot {{psocoptera-stub ...
'', ''
Megalagrion ''Megalagrion'' is a genus of damselflies in the family Coenagrionidae. It contains approximately 26 species, all of which are endemic to Hawaii. Megalagrion damselflies are the only native damselflies in Hawaii, and are referred to as " pinapi ...
'', '' Prognathogryllus'', ''
Nesosydne ''Nesosydne'' is a genus of true bugs belonging to the family Delphacidae Delphacidae is a family of planthoppers containing about 2000 species, distributed worldwide. Delphacids are separated from other "hoppers" by the prominent spur on the ...
'', ''
Cephalops ''Cephalops'' is a genus of flies belonging to the family Pipunculidae. The genus has cosmopolitan distribution. Species *'' Cephalops abditus'' (Hardy, 1949) *'' Cephalops acklandi'' Kozánek & De Meyer, 1992 *'' Cephalops acrothrix'' (Perkin ...
'', '' Trupanea'', and the tribe
Platynini Platynini is a large tribe of ground beetles in the family Carabidae Ground beetles are a large, cosmopolitan family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 ...
—all suggesting repeated radiations among the islands.


Other islands

Phylogenetic studies of a species of crab spider (''
Misumenops rapaensis ''Misumenops'' is a common genus of crab spider with more than 50 described species. The majority of the species Mesumenops, more than 80, have been transferred to 13 genera: '' Ansiea'', '' Demogenes'', '' Diaea'', '' Ebelingia'', '' Ebrechtel ...
'') in the genus
Thomisidae The Thomisidae are a family of spiders, including about 170 genera and over 2,100 species. The common name crab spider is often linked to species in this family, but is also applied loosely to many other families of spiders. Many members of th ...
located on the
Austral Islands The Austral Islands (french: Îles Australes, officially ''Archipel des Australes;'' ty, Tuha'a Pae) are the southernmost group of islands in French Polynesia, an overseas country of the French Republic in the South Pacific. Geographically, t ...
have established the, "sequential colonization of helineage down the Austral archipelago toward younger islands". ''M. rapaensis'' has been traditionally thought of as a single species; whereas this particular study found distinct genetic differences corresponding to the sequential age of the islands. The figwart plant species ''Scrophularia lowei'' is thought to have arisen through a peripatric speciation event, with the more widespread mainland species, ''Scrophularia arguta'' dispersing to the
Macaronesian Macaronesia (Portuguese: ''Macaronésia,'' Spanish: ''Macaronesia'') is a collection of four volcanic archipelagos in the North Atlantic, off the coasts of Africa and Europe. Each archipelago is made up of a number of Atlantic oceanic island ...
islands. Other members of the same genus have also arisen by single colonization events between the islands.


Species patterns on continents

The occurrence of peripatry on continents is more difficult to detect due to the possibility of vicariant explanations being equally likely. However, studies concerning the Californian plant species ''
Clarkia ''Clarkia'' is a genus within the flowering plant family Onagraceae. Over 40 species are currently classified in ''Clarkia''; almost all are native to western North America, though one species (''Clarkia tenella'') is native to South America. ...
biloba'' and ''C. lingulata '' strongly suggest a peripatric origin. In addition, a great deal of research has been conducted on several species of land snails involving
chirality Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from ...
that suggests peripatry (with some authors noting other possible interpretations). The chestnut-tailed antbird (''Sciaphylax hemimelaena'') is located within the
Noel Kempff Mercado National Park Noel Kempff Mercado National Park is a national park in northeast Santa Cruz Department, Province of José Miguel de Velasco, Bolivia, on the border with Brazil. Description Noel Kempff Mercado National Park covers of land, which includes the ...
(Serrania de Huanchaca) in Bolivia. Within this region exists a forest fragment estimated to have been isolated for 1000–3000 years. The population of ''S. hemimelaena'' antbirds that reside in the isolated patch express significant song divergence; thought to be an "early step" in the process of peripatric speciation. Further, peripheral isolation "may partly explain the dramatic diversification of
suboscines The Tyranni (suboscines) are a suborder of passerine birds that includes more than 1,000 species, the large majority of which are South American. It is named after the type genus ''Tyrannus''. These have a different anatomy of the syrinx musc ...
in
Amazonia The Amazon rainforest, Amazon jungle or ; es, Selva amazónica, , or usually ; french: Forêt amazonienne; nl, Amazoneregenwoud. In English, the names are sometimes capitalized further, as Amazon Rainforest, Amazon Forest, or Amazon Jungle. ...
". The montane spiny throated reed frog
species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...
(genus: '' Hyperolius'') originated through occurrences of peripatric speciation events. Lucinda P. Lawson maintains that the species' geographic ranges within the Eastern
Afromontane The Afromontane regions are subregions of the Afrotropical realm, one of the Earth's eight biogeographic realms, covering the plant and animal species found in the mountains of Africa and the southern Arabian Peninsula. The Afromontane regions of ...
Biodiversity Hotspot support a peripatric model that is driving speciation; suggesting that this mode of speciation may play a significant role in "highly fragmented ecosystems". In a study of the phylogeny and biogeography of the land snail genus ''
Monacha ''Monacha'' is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the subfamily Trochulininae Lindholm, 1927 of the family Hygromiidae, the hairy snails and their allies. MolluscaBase eds. (2021). MolluscaBa ...
'', the species ''M. ciscaucasica'' is thought to have speciated peripatrically from a population of ''M. roseni''. In addition, ''M. claussi'' consists of a small population located on the peripheral of the much larger range of ''M. subcarthusiana'' suggesting that it also arose by peripatric speciation. Red spruce ('' Picea rubens'') has arisen from an isolated population of black spruce (''
Picea mariana ''Picea mariana'', the black spruce, is a North American species of spruce tree in the pine family. It is widespread across Canada, found in all 10 provinces and all 3 territories. It is the official tree of the province of Newfoundland and Labr ...
''). During the
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
, a population of black spruce became geographically isolated, likely due to
glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate bet ...
. The geographic range of the black spruce is much larger than the red spruce. The red spruce has significantly lower genetic diversity in both its DNA and its
mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
than the black spruce. Furthermore, the genetic variation of the red spruce has no unique mitochondrial
haplotype A haplotype ( haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. Many organisms contain genetic material ( DNA) which is inherited from two parents. Normally these organisms have their DNA o ...
s, only subsets of those in the black spruce; suggesting that the red spruce speciated peripatrically from the black spruce population. It is thought that the entire genus ''
Picea A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...
'' in North America has diversified by the process of peripatric speciation, as numerous pairs of closely related species in the genus have smaller southern population ranges; and those with overlapping ranges often exhibit weak reproductive isolation. Using a phylogeographic approach paired with ecological niche models (''i.e.'' prediction and identification of expansion and contraction species ranges into suitable habitats based on current
ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for ...
s, correlated with fossil and molecular data), researchers found that the
prairie dog Prairie dogs (genus ''Cynomys'') are herbivorous Burrow, burrowing Marmotini , ground squirrels native to the grasslands of North America. Within the genus are five species: black-tailed prairie dog, black-tailed, white-tailed prairie dog, wh ...
species ''
Cynomys mexicanus The Mexican prairie dog (''Cynomys mexicanus'') is a diurnal burrowing rodent native to Mexico. Treatment as an agricultural pest has led to its status as an endangered species. They are closely related to squirrels, chipmunks, and marmots. '' ...
'' speciated peripatrically from ''
Cynomys ludovicianus The black-tailed prairie dog (''Cynomys ludovicianus'') is a rodent of the family Sciuridae found in the Great Plains of North America from about the United States-Canada border to the United States-Mexico border. Unlike some other prairie dogs, ...
'' approximately 230,000 years ago. North American glacial cycles promoted range expansion and contraction of the prairie dogs, leading to the isolation of a relic population in a refugium located in the present day
Coahuila Coahuila (), formally Coahuila de Zaragoza (), officially the Free and Sovereign State of Coahuila de Zaragoza ( es, Estado Libre y Soberano de Coahuila de Zaragoza), is one of the 32 states of Mexico. Coahuila borders the Mexican states of N ...
, Mexico. This distribution and paleobiogeographic pattern correlates with other species expressing similar biographic range patterns such as with the ''
Sorex cinereus The cinereus shrew or masked shrew (''Sorex cinereus'') is a small shrew found in Alaska, Canada, and the northern United States. This is the most widely distributed shrew in North America, where it is also known as the common shrew. Descriptio ...
'' complex.


Laboratory experiments

Peripatric speciation has been researched in both laboratory studies and nature. Jerry Coyne and
H. Allen Orr H. Allen Orr (born 1960) is the Shirley Cox Kearns Professor of Biology at the University of Rochester. Education and career Orr earned his bachelor's degree in Biology and Philosophy from the College of William and Mary and his Ph.D. in Biology ...
in ''Speciation'' suggest that most laboratory studies of allopatric speciation are also examples of peripatric speciation due to their small population sizes and the inevitable divergent selection that they undergo. Much of the laboratory research concerning peripatry is inextricably linked to
founder effect In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1942, us ...
research. Coyne and Orr conclude that selection's role in speciation is well established, whereas
genetic drift Genetic drift, also known as allelic drift or the Wright effect, is the change in the frequency of an existing gene variant (allele) in a population due to random chance. Genetic drift may cause gene variants to disappear completely and there ...
's role is unsupported by experimental and field data—suggesting that founder-effect speciation does not occur. Nevertheless, a great deal of research has been conducted on the matter, and one study conducted involving
bottleneck Bottleneck literally refers to the narrowed portion (neck) of a bottle near its opening, which limit the rate of outflow, and may describe any object of a similar shape. The literal neck of a bottle was originally used to play what is now known as ...
populations of ''
Drosophila pseudoobscura ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many speci ...
'' found evidence of isolation after a single bottleneck. The table is a non-exhaustive table of laboratory experiments focused explicitly on peripatric speciation. Most of the studies also conducted experiments on vicariant speciation as well. The "replicates" column signifies the number of lines used in the experiment—that is, how many independent populations were used (not the population size or the number of generations performed).


References

{{DEFAULTSORT:Peripatric Speciation Biogeography Ecology Evolutionary biology Speciation