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Endemism is the state of a
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 appropriate s ...
being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are
indigenous Indigenous may refer to: *Indigenous peoples *Indigenous (ecology), presence in a region as the result of only natural processes, with no human intervention *Indigenous (band), an American blues-rock band *Indigenous (horse), a Hong Kong racehorse ...
to a place are not endemic to it if they are also found elsewhere. For example, the
Cape sugarbird The Cape sugarbird (''Promerops cafer'') is one of the eight bird species endemic to the Fynbos biome of the Western Cape and Eastern Cape provinces of South Africa. Description The Cape sugarbird is a grey-brown bird that is easily recognisab ...
is found exclusively in southwestern
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...
and is therefore said to be ''endemic'' to that particular part of the world. An endemic species can be also be referred to as an ''endemism'' or in scientific literature as an ''endemite''. For example '' Cytisus aeolicus'' is an endemite of the Italian flora.Genetic diversity in Cytisus aeolicus Guss. (Leguminosae), a rare endemite of the Italian flora
/ref> '' Adzharia renschi'' was once believed to be an endemite of the
Caucasus The Caucasus () or Caucasia (), is a region between the Black Sea and the Caspian Sea, mainly comprising Armenia, Azerbaijan, Georgia (country), Georgia, and parts of Southern Russia. The Caucasus Mountains, including the Greater Caucasus range ...
, but it was later discovered to be a non-indigenous species from South America belonging to a different
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
. The extreme opposite of an endemic species is one with a cosmopolitan distribution, having a global or widespread range. A rare alternative term for a species that is endemic is "precinctive", which applies to species (and other taxonomic levels) that are restricted to a defined geographical area. Other terms that sometimes are used interchangeably, but less often, include autochthonal, autochthonic, and indigenous, however these terms do not reflect the status of a species that specifically belongs only to a determined place.


Etymology


History of the concept

The word ''endemic'' is from
New Latin New Latin (also called Neo-Latin or Modern Latin) is the revival of Literary Latin used in original, scholarly, and scientific works since about 1500. Modern scholarly and technical nomenclature, such as in zoological and botanical taxonomy ...
''endēmicus'', from
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
ἔνδημος, ''éndēmos'', "native". ''Endēmos'' is formed of ''en'' meaning "in", and ''dēmos'' meaning "the people". The word entered the English language as a
loan word A loanword (also loan word or loan-word) is a word at least partly assimilated from one language (the donor language) into another language. This is in contrast to cognates, which are words in two or more languages that are similar because the ...
from French ''endémique'', and originally seems to have been used in the sense of diseases which occur at a constant amount in a country, as opposed to epidemic diseases, which are exploding in cases. The word was used in biology in 1872 to mean a species restricted to a specific location by
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended ...
. The more uncommon term 'precinctive' has been used by some entomologists as the equivalent of 'endemic'. ''Precinctive'' was coined in 1900 by David Sharp when describing the Hawaiian insects, as he was uncomfortable with the fact that the word '
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 ...
' is often associated with diseases. 'Precinctive' was first used in botany by
Vaughan MacCaughey Vaughan () (2021 population 323,103) is a city in Ontario, Canada. It is located in the Regional Municipality of York, just north of Toronto. Vaughan was the fastest-growing municipality in Canada between 1996 and 2006 with its population increas ...
in Hawaii in 1917.


Overview

Endemism in general excludes examples kept by humans in
botanical garden A botanical garden or botanic gardenThe terms ''botanic'' and ''botanical'' and ''garden'' or ''gardens'' are used more-or-less interchangeably, although the word ''botanic'' is generally reserved for the earlier, more traditional gardens, an ...
s or
zoological park A zoo (short for zoological garden; also called an animal park or menagerie) is a facility in which animals are kept within enclosures for public exhibition and often bred for conservation purposes. The term ''zoological garden'' refers to zool ...
s, as well as populations introduced outside of their native ranges. Juan J. Morrone states that a species may be endemic to any particular geographic region, regardless of size, thus the cougar is endemic to the Americas, however, endemism is normally used only where there is a considerable restriction in the area of distribution. All species are not endemics, some species may be cosmopolitan. All endemics are not necessarily rare; some might be common where they occur. All rare species are not necessarily endemics, some may have a large range but be rare throughout this range. Endemism is caused by historical and ecological factors.
Vicariant 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 ...
events caused by drifting continents, dispersal and extinction are some possible historical factors. Ecological factors can explain the present limits on a distribution. Endemic species are especially likely to develop on geographically and biologically isolated areas such as islands and remote island groups, including
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...
, the
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 Ecuador ...
and
Socotra Socotra or Soqotra (; ar, سُقُطْرَىٰ ; so, Suqadara) is an island of the Republic of Yemen in the Indian Ocean, under the ''de facto'' control of the UAE-backed Southern Transitional Council, a secessionist participant in Yemen’ ...
, because of the potential for isolation and therefore evolution through
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 ...
.
Darwin's finches Darwin's finches (also known as the Galápagos finches) are a group of about 18 species of passerine birds. They are well known for their remarkable diversity in beak form and function. They are often classified as the subfamily Geospizinae or t ...
in the Galápagos archipelago are examples of species endemic to islands. Similarly, isolated mountainous regions like the
Ethiopian Highlands The Ethiopian Highlands is a rugged mass of mountains in Ethiopia in Northeast Africa. It forms the largest continuous area of its elevation in the continent, with little of its surface falling below , while the summits reach heights of up to . ...
, or large bodies of water far from other lakes, like Lake Baikal, can also have high rates of endemism. The stability of a region's climate and habitat through time may also contribute to high rates of endemism (especially paleoendemism), acting as refuges for species during times of climate change like
Ice Ages An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...
. These changes may have caused species to repeatedly restrict their ranges into these refuges, leading to regions with many small-ranged species. In many cases biological factors, such as low rates of dispersal or returning to the spawning area (
philopatry Philopatry is the tendency of an organism to stay in or habitually return to a particular area. The causes of philopatry are numerous, but natal philopatry, where animals return to their birthplace to breed, may be the most common. The term derive ...
), can cause a particular group of organisms to have high speciation rates and thus many endemic species. for example, cichlids in the East African
Rift Lakes The Rift Valley lakes are a series of lakes in the East African Rift valley that runs through eastern Africa from Ethiopia in the north to Malawi in the south, and includes the African Great Lakes in the south. These include some of the world's ...
have diversified into many more endemic species than the other fish families in the same lakes, possibly due to such factors. Plants which become endemic on isolated islands are often those which have a ''high'' rate of dispersal, and are able to reach such islands by being dispersed by birds. While birds are less likely to be endemic to a region based on their ability to disperse via flight, there are over 2,500 species which are considered endemic, meaning that the species is restricted to an area less than 5 million hectares.
Microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s were traditionally not believed to form endemics. The hypothesis 'everything is everywhere', first stated in
Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () Dutch may also refer to: Places * Dutch, West Virginia, a community in the United States * Pennsylvania Dutch Country People E ...
by Lourens G.M. Baas Becking in 1934, describes the theory that the distribution of organisms smaller than 2mm is cosmopolitan where habitats occur that support their growth.


Subtypes

The first subcategories were first introduced by
Claude P. E. Favager Claude may refer to: __NOTOC__ People and fictional characters * Claude (given name), a list of people and fictional characters * Claude (surname), a list of people * Claude Lorrain (c. 1600–1682), French landscape painter, draughtsman and etcher ...
and Juliette Contandriopoulis in 1961: schizoendemics, apoendemics and patroendemics. Using this work, Ledyard Stebbins and Jack Major then introduced the concepts of neoendemics and paleoendemics in 1965 to describe the endemics of
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
. Endemic taxa can also be classified into autochthonous, allochtonous, taxonomic relicts and biogeographic relicts. Paleoendemism refers to species that were formerly widespread but are now restricted to a smaller area.
Neoendemism Neoendemism is one of two sub-categories of endemism, the ecological state of a species being unique to a defined geographic location. Specifically, neoendemic species are those that have recently arisen, through divergence and reproductive isola ...
refers to species that have recently arisen, such as through divergence and reproductive isolation or through hybridization and
polyploidy Polyploidy is a condition in which the biological cell, cells of an organism have more than one pair of (Homologous chromosome, homologous) chromosomes. Most species whose cells have Cell nucleus, nuclei (eukaryotes) are diploid, meaning they ha ...
in plants, and have not dispersed beyond a limited range. Paleoendemism is more or less synonymous with the concept of a '
relict species In biogeography and paleontology, a relict is a population or taxon of organisms that was more widespread or more diverse in the past. A relictual population is a population currently inhabiting a restricted area whose range was far wider during a ...
': a
population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...
or
taxon In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...
of organisms that was more widespread or more diverse in the past. A 'relictual population' is a population that currently occurs in a restricted area, but whose original
range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...
was far wider during a previous
geologic epoch The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochrono ...
. Similarly, a 'relictual taxon' is a taxon (e.g. species or other lineage) that is the sole surviving representative of a formerly diverse group. Schizoendemics, apoendemics and patroendemics can all be classified as types of neoendemics. Schizoendemics arise from a wider distributed taxon which has become reproductively isolated without becoming (potentially) genetically isolated – a schizoendemic has the same chromosome count as the parent taxon it evolved from. An apoendemic is a
polyploid Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...
of the parent taxon (or taxa in the case of allopolyploids), whereas a patroendemic has a lower, diploid chromosome count than the related, more widely distributed polyploid taxon. Mikio Ono coined the term 'aneuendemics' in 1991 for species which have more or less chromosomes than their relatives due to
aneuploidy Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any ...
. Pseudoendemics are taxa which have possibly recently evolved from a mutation. Holoendemics is a concept introduced by Richardson 1978 to describe taxa which have remained endemic to a restricted distribution for a very long time. In a 2000 paper, Myers and de Grave further attempted to redefine the concept. In their view, everything is endemic, even cosmopolitan species are endemic to Earth, and earlier definitions restricting endemics to specific locations are wrong. Thus the subdivisions neoendemics and paleoendemics are without merit regarding the study of distributions, because these concepts consider that an endemic has a distribution limited to one place. Instead, they propose four different categories: holoendemics, euryendemics, stenoendemics and rhoendemics. In their scheme cryptoendemics and euendemics are further subdivisions of rhoendemics. In their view, a holoendemic is a cosmopolitan species. Stenoendemics, also known as local endemics, have a reduced distribution and are synonymous with the word 'endemics' in the traditional sense, whereas euryendemics have a larger distribution -both these have distributions which are more or less continuous. A rhoendemic has a disjunct distribution. Where this disjunct distribution is caused by vicariance, in a euendemic the vicariance was geologic in nature, such as the movement of tectonic plates, but in a cryptoendemic the disjunct distribution was due to extinction of the intervening populations. There is yet another possible situation which can cause a disjunct distribution, where a species is able to colonize new territories by crossing over areas of unsuitable habitat, such as plants colonizing an island – this situation they dismiss as extremely rare and do not devise a name for. Traditionally, none of Myers and de Grave's categories would be considered endemics except stenoendemics.


Soil

Serpentine soils act as '
edaphic Edaphology (from Greek , ''edaphos'', "ground",, '' -logia'') is concerned with the influence of soils on living beings, particularly plants. It is one of two main divisions of soil science, the other being pedology. Edaphology includes the stu ...
islands' of low fertility and these soils lead to high rates of endemism. These soils are found in the Balkan Peninsula, Turkey, Alps, Cuba, New Caledonia, the North American Appalachians, and a scattered distribution in California, Oregon, and Washington and elsewhere. For example, Mayer and Soltis considered the widespread subspecies ''Streptanthus glandulosus'' subsp. ''glandulosus'' which grows on normal soils, to be a paleoendemic, whereas closely related endemic forms of ''S. glandulosus'' occurring on serpentine soil patches are neoendemics which recently evolved from subsp. ''glandulosus''.


Islands

Isolated islands commonly develop a number of endemics. Many species and other higher taxonomic groups exist in very small terrestrial or aquatic islands, which restrict their distribution. The Devil's Hole pupfish, ''
Cyprinodon diabolis The Devils Hole pupfish (''Cyprinodon diabolis'') is a critically endangered species of the family Cyprinodontidae (pupfishes) found only in Devils Hole, a water-filled cavern in the US state of Nevada. It was first described as a species in ...
,'' has its whole native population restricted to a spring that is 20 x 3 meters, in
Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
's
Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily ...
. This 'aquatic island' is connected to an underground basin; however, the population present in the pool remains isolated. Other areas very similar to the Galapagos Islands of the Pacific Ocean exist and foster high rates of endemism. The Socotra Archipelago of Yemen, located in the Indian Ocean, has seen a new endemic species of parasitic leech, '' Myxobdella socotrensis,'' appear. This species is restricted to freshwater springs, where it may attach to and feed upon native crabs.


Mountains

Mountains can be seen as '
sky islands Sky islands are isolated mountains surrounded by radically different lowland environments. The term originally referred to those found on the Mexican Plateau, and has extended to similarly isolated high-elevation forests. The isolation has si ...
': refugia of endemics because species that live in the cool climates of mountain peaks are geographically isolated. For example, in the Alpes-Maritimes department of France, '' Saxifraga florulenta'' is an endemic plant that may have evolved in the Late Miocene and could have once been widespread across the Mediterranean Basin. Volcanoes also tend to harbor a number of endemic species. Plants on volcanoes tend to fill a specialized
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 ...
, with a very restrictive range, due to the unique environmental characteristics. The Kula Volcano, one of the fourteen volcanoes in Turkey, is home to 13 endemic species of plants.


Conservation

Endemics might more easily become
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...
or extinct because they are already restricted in distribution. This puts endemic plants and animals at greater risk than widespread species during the rapid
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
of this century. Some scientists claim that the presence of endemic species in an area is a good method to find geographical regions that can be considered priorities for conservation. Endemism can thus be studied as a proxy for measuring
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
of a region. The concept of finding endemic species that occur in the same region to designate 'endemism hotspots' was first proposed by Paul Müller in a 1973 book. According to him, this is only possible where 1.) the
taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
of the species in question is not in dispute; 2.) the species distribution is accurately known; and 3.) the species have relatively small distributional ranges. In a 2000 article, Myers ''et al''. used the standard of having more than 0.5% of the world's plant species being endemics of the region to designate 25 geographical areas of the world as '
biodiversity hotspot A biodiversity hotspot is a biogeographic region with significant levels of biodiversity that is threatened by human habitation. Norman Myers wrote about the concept in two articles in ''The Environmentalist'' in 1988 and 1990, after which the c ...
s'. In response to the above, the
World Wildlife Fund The World Wide Fund for Nature Inc. (WWF) is an international non-governmental organization founded in 1961 that works in the field of wilderness preservation and the reduction of human impact on the environment. It was formerly named the Wo ...
has split the world into a few hundred geographical ' ecoregions'. These have been designed to include as many species as possible that only occur in a single ecoregion, and these species are thus 'endemics' to these ecoregions. Since plenty of these ecoregions have a high prevalence of endemics existing within them, many National Parks have been formed around or within them to further promote conservation. The
Caparaó National Park Caparaó National Park ( pt, Parque Nacional do Caparaó) is a national park created in 1961 to protect the Caparaó Mountains, located on the border between Minas Gerais and Espírito Santo states in Brazil. Pico da Bandeira, one of the highest ...
was formed in the Atlantic Forest, a biodiversity hotspot located in Brazil, in order to help protect valuable and vulnerable species. Other scientists have argued that endemism is not an appropriate measure of biodiversity, because the levels of threat or biodiversity are not actually correlated to areas of high endemism. When using bird species as an example, it was found that only 2.5% of biodiversity hotspots correlate with endemism and the threatened nature of a geographic region. A similar pattern had been found previously regarding mammals, ''
Lasioglossum The sweat bee genus ''Lasioglossum'' is the largest of all bee genera, containing over 1700 species in numerous subgenera worldwide.Gibbs, J., et al. (2012)Phylogeny of halictine bees supports a shared origin of eusociality for ''Halictus'' and ...
'' bees,
Plusiinae Plusiinae is a smallish (for noctuid standards) subfamily of the moth family Noctuidae. As the Noctuidae appear to be a paraphyletic assemblage, the Plusiinae may eventually be raised to family status (Weller ''et al.'' 1994). Comparison of Eura ...
moths, and swallowtail butterflies in North America: these different groups of taxa did not correlate geographically with each other regarding endemism and species richness. Especially using mammals as
flagship species In conservation biology, a flagship species is a species chosen to raise support for biodiversity conservation in a given place or social context. Definitions have varied, but they have tended to focus on the strategic goals and the socio-economi ...
proved to be a poor system of identifying and protecting areas of high invertebrate biodiversity. In response to this, other scientists again defended the concept by using WWF ecoregions and reptiles, finding that most reptile endemics occur in WWF ecoregions with high biodiversity. Other conservation efforts for endemics include keeping captive and semi-captive populations in zoological parks and botanical gardens. These methods are
ex situ Svalbard GLOBAL SEED BANK, an ''ex situ'' conservation. ''Ex situ'' conservation literally means, "off-site conservation". It is the process of protecting an endangered species, variety or breed, of plant or animal outside its natural habitat; ...
("off site") conservation methods. The use of such methods may not only offer refuge and protection for individuals of declining or vulnerable populations, but it may also allow biologists valuable opportunities to research them as well.


References


External links

* {{DEFAULTSORT:Endemism Biodiversity Habitat Biology terminology