Endemism

Endemism is the ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. The extreme opposite of endemism is cosmopolitan distribution. An alternative term for a species that is endemic is precinctive, which applies to species (and subspecific categories) that are restricted to a defined geographical area.

Orange-breasted Sunbird (Nectarinia violacea)
The orange-breasted sunbird (Nectarinia violacea) is exclusively found in fynbos vegetation.
Bicolored Frog ( Clinotarsus curtipes )
Bicolored frog (Clinotarsus curtipes) is endemic to the Western Ghats of India

Etymology

The word endemic is from New Latin endēmicus, from Greek ενδήμος, endēmos, "native". Endēmos is formed of en meaning "in", and dēmos meaning "the people".[1] The term "precinctive" has been suggested by some scientists,[a] and was first used in botany by MacCaughey in 1917. It is the equivalent of "endemism".[2] Precinction was perhaps first used by Frank and McCoy.[3][4] Precinctive seems to have been coined by David Sharp when describing the Hawaiian fauna in 1900:[5] "I use the word precinctive in the sense of 'confined to the area under discussion' ... 'precinctive forms' means those forms that are confined to the area specified." That definition excludes artificial confinement of examples by humans in far-off botanical gardens or zoological parks.

Overview

Chorus cicada
Chorus cicada, a species endemic to New Zealand

Physical, climatic, and biological factors can contribute to endemism. The orange-breasted sunbird is exclusively found in the fynbos vegetation zone of southwestern South Africa. The glacier bear is found only in limited places in Southeast Alaska. Political factors can play a part if a species is protected, or actively hunted, in one jurisdiction but not another.

There are two subcategories of endemism: paleoendemism and neoendemism. Paleoendemism refers to species that were formerly widespread but are now restricted to a smaller area. Neoendemism refers to species that have recently arisen, such as through divergence and reproductive isolation or through hybridization and polyploidy in plants.

Endemic types or species are especially likely to develop on geographically and biologically isolated areas such as islands and remote island groups, such as Hawaii, the Galápagos Islands, and Socotra; they can equally develop in biologically isolated areas such as the highlands of Ethiopia, or large bodies of water far from other lakes, like Lake Baikal. Hydrangea hirta is an example of an endemic species found in Japan.

Endemics can easily become endangered or extinct if their restricted habitat changes, particularly—but not only—due to human actions, including the introduction of new organisms. There were millions of both Bermuda petrels and "Bermuda cedars" (actually junipers) in Bermuda when it was settled at the start of the seventeenth century. By the end of the century, the petrels were thought extinct. Cedars, already ravaged by centuries of shipbuilding, were driven nearly to extinction in the twentieth century by the introduction of a parasite. Bermuda petrels and cedars are now rare, as are other species endemic to Bermuda.

Threats to highly endemistic regions

Principal causes of habitat degradation and loss in highly endemistic ecosystems include agriculture, urban growth, surface mining, mineral extraction, logging operations[6][7] and slash-and-burn agriculture.

Notes

  1. ^ Precinctivity

References

  1. ^ "Endemic". Reference.com. Retrieved 6 december 2014.
  2. ^ MacCaughey, Vaughaun 1917. A survey of the Hawaiian land flora. Botanical Gazette 64: 89–114 [see p. 92]. https://www.jstor.org/stable/2469367
  3. ^ Frank, J. H. and McCoy, E. D. 1990. Endemics and epidemics of shibboleths and other things causing chaos. Florida Entomologist 73: 1–9. http://journals.fcla.edu/flaent/article/view/58577/56256
  4. ^ Frank, J. H. and McCoy, E. D. 1995. Precinctive insect species in Florida. Florida Entomologist 78: 21–35. [also uses word precinction]. http://journals.fcla.edu/flaent/article/view/74657/72315
  5. ^ Sharp, D. 1900. Coleoptera. I. Coleoptera Phytophaga, pp. 91–116 in D. Sharp [ed.]. Fauna Hawaiiensis, Being the Land-Fauna of the Hawaiian Islands. Cambridge Univ. Press; Cambridge, vol. 2 part 3 [see p. 91].
  6. ^ Fred Smiet (1982). Threats to the Spice Islands. Oryx, 16, pp 323–328 doi:10.1017/S0030605300017774
  7. ^ "Frontiers in Ecology and the Environment 5". Frontiers in Ecology and the Environment. 5 (1): 25–32. doi:10.1890/1540-9295(2007)5[25:ARFDAL]2.0.CO;2.

Further reading

Central Highlands (Madagascar)

The Central Highlands, Central High Plateau, or Hauts-Plateaux are a mountainous biogeographical region in central Madagascar. They include the contiguous part of the island's interior above 800 m (2,600 ft) altitude. The Central Highlands are separated from the Northern Highlands of the northern tip of Madagascar by a low-lying valley, the Mandritsara Window, which has apparently acted as a barrier to dispersal for species in the highlands, leading to species pairs such as Voalavo gymnocaudus and Voalavo antsahabensis in the Northern and Central Highlands. Species restricted to the Central Highlands include the bats Miniopterus manavi and Miniopterus sororculus; the rodents Brachyuromys betsileoensis aand Voalavo antsahabensis; the tenrecs Hemicentetes nigriceps and Oryzorictes tetradactylus; and the lemur Cheirogaleus sibreei. Because of the continuous habitat of the Central Highlands, there is little local endemism, unlike the Northern Highlands.

Cosmopolitan distribution

In biogeography, a taxon is said to have a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. Such a taxon is said to exhibit cosmopolitanism or cosmopolitism. The opposite extreme is endemism.

Endemic (epidemiology)

In epidemiology, an infection is said to be endemic (from Greek ἐν en "in, within" and δῆμος demos "people") in a population when that infection is constantly maintained at a baseline level in a geographic area without external inputs. For example, chickenpox is endemic (steady state) in the UK, but malaria is not. Every year, there are a few cases of malaria reported in the UK, but these do not lead to sustained transmission in the population due to the lack of a suitable vector (mosquitoes of the genus Anopheles). While it might be common to say that AIDS is "endemic" in Africa, meaning found in an area, this is a use of the word in its etymological, rather than epidemiological, form. AIDS cases in Africa are increasing, so the disease is not in an endemic steady state. It is correct to call the spread of AIDS in Africa an epidemic.

For an infection that relies on person-to-person transmission to be endemic, each person who becomes infected with the disease must pass it on to one other person on average. Assuming a completely susceptible population, that means that the basic reproduction number (R0) of the infection must equal 1. In a population with some immune individuals, the basic reproduction number multiplied by the proportion of susceptible individuals in the population (S) must be 1. This takes account of the probability of each individual to whom the disease may be transmitted being susceptible to it, effectively discounting the immune sector of the population. So, for a disease to be in an endemic steady state it is:

In this way, the infection neither dies out nor does the number of infected people increase exponentially but the infection is said to be in an endemic steady state. An infection that starts as an epidemic will eventually either die out (with the possibility of it resurging in a theoretically predictable cyclical manner) or reach the endemic steady state, depending on a number of factors, including the virulence of the disease and its mode of transmission.

If a disease is in endemic steady state in a population, the relation above allows us to estimate the R0 (an important parameter) of a particular infection. This in turn can be fed into the mathematical model of an epidemic.

Endemic birds of Madagascar and western Indian Ocean islands

This article is one of a series providing information about endemism among birds in the world's various zoogeographic zones. For an overview of this subject see Endemism in birds.

Fauna of Ghana

The wildlife of Ghana is composed of its biodiversity of flora and fauna.

Flora of Colombia

The Flora of Colombia is characterized by 130,000 species of plants that have been described within Colombian territory.

Island restoration

The ecological restoration of islands, or island restoration, is the application of the principles of ecological restoration to islands and island groups. Islands, due to their isolation, are home to many of the world's endemic species, as well as important breeding grounds for seabirds and some marine mammals. Their ecosystems are also very vulnerable to human disturbance and particularly to introduced species, due to their small size. Island groups such as New Zealand and Hawaii have undergone substantial extinctions and losses of habitat. Since the 1950s several organisations and government agencies around the world have worked to restore islands to their original states; New Zealand has used them to hold natural populations of species that would otherwise be unable to survive in the wild. The principal components of island restoration are the removal of introduced species and the reintroduction of native species.

List of endemic birds of Australia

This article is one of a series providing information about endemism among birds in the world's various zoogeographic zones. For an overview of this subject see Endemism in birds.

List of endemic birds of Borneo

This article is one of a series providing information about endemism among birds in the world's various zoogeographic zones. For an overview of this subject see Endemism in birds.

List of endemic birds of Hawaii

There are 71 known taxa of birds endemic to the Hawaiian Islands, of which 30 are extinct, 6 possibly extinct and 30 of the remaining 48 species and subspecies are listed as endangered or threatened by the United States Fish and Wildlife Service. Habitat loss and avian disease are thought to have had the greatest effect on endemic bird species in Hawaii.

List of endemic birds of New Caledonia

This article is one of a series providing information about endemism among birds in the world's various zoogeographic zones. For an overview of this subject, see Endemism in birds.

List of endemic birds of Taiwan

This article is one of a series providing information about endemism among birds in the world's various zoogeographic zones. For an overview of this subject see Endemism in birds.

List of endemic birds of eastern North America

This article is one of a series providing information about endemism among birds in the World's various zoogeographic zones. For an overview of this subject see Endemism in birds.

This article covers eastern North America, i.e. the regions of the United States and Canada which lie east of the Rocky Mountains.

List of endemic birds of the Galápagos Islands

This article is one of a series providing information about endemism among birds in the world's various zoogeographic zones. For an overview of this subject see Endemism in birds.

List of endemic birds of the Philippines

This article is one of a series providing information about endemism among bois in the world's various zoogeographic zones. For an overview of this subject see Endemism in birds.

List of endemic species of Taiwan

The endemic species of Taiwan are organisms that are endemic to the island of Taiwan— that is, they occur nowhere else on Earth.

Percentages of endemic animals of all living species in Taiwan.

Percentages of endemic plants of all living species in Taiwan.

Movile Cave

Movile Cave (Romanian: Peștera Movile) is a cave near Mangalia, Constanța County, Romania discovered by Cristian Lascu in 1986 a few kilometers from the Black Sea coast. It is notable for its unique groundwater ecosystem rich in hydrogen sulfide and carbon dioxide but low in oxygen. Life in the cave has been separated from the outside for the past 5.5 million years and it is based completely on chemosynthesis rather than photosynthesis.

Sky island

Sky islands are isolated mountains surrounded by radically different lowland environments. The term originally referred to those found near the southern borders of Arizona and New Mexico, and has extended to similarly isolated high-altitude forests. The isolation has significant implications for these natural habitats. The American Southwest region began warming up between ∼20,000–10,000 years BP and atmospheric temperatures increased substantially, resulting in the formation of vast deserts that isolated the Sky Islands. Endemism, altitudinal migration, and relict populations are some of the natural phenomena to be found on sky islands.

The complex dynamics of species richness on sky islands draws attention from the discipline of biogeography, and likewise the biodiversity is of concern to conservation biology. One of the key elements of a sky island is separation by physical distance from the other mountain ranges, resulting in a habitat island, such as a forest surrounded by desert.

Some sky islands serve as refugia for boreal species stranded by warming climates since the last glacial period. In other cases, localized populations of plants and animals tend towards speciation, similar to oceanic islands such as the Galápagos Islands of Ecuador.

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