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Local extinction
 
 
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Local extinction is where a species
Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring....
 (or other taxon
Taxon

A taxon or taxonomic unit is a name designating an organism or a group of organisms. In biological nomenclature according to Carl Linnaeus, a taxon is assigned a taxonomic rank and can be placed at a particular level in a systematic hierarchy reflecting evolutionary relationships....
) ceases to exist in the chosen area of study, but still exists elsewhere. This phenomenon is also known as extirpation. Local extinctions are contrasted with global extinctions.

Local extinctions may be followed by a replacement of the species taken from other locations; wolf reintroduction
Wolf reintroduction

Wolf reintroduction involves the artificial reestablishment of a population of gray wolf into areas where they had been previously Extirpation....
 is an example of this.

Conservation
Local extinctions mark a change in the ecology
Ecology

Ecology is the science study of the distribution and Abundance of life and the interactions between organisms and their nature environment ....
 of an area.

The area of study chosen may reflect a natural subpopulation, political boundaries, or both.






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Local extinction is where a species
Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring....
 (or other taxon
Taxon

A taxon or taxonomic unit is a name designating an organism or a group of organisms. In biological nomenclature according to Carl Linnaeus, a taxon is assigned a taxonomic rank and can be placed at a particular level in a systematic hierarchy reflecting evolutionary relationships....
) ceases to exist in the chosen area of study, but still exists elsewhere. This phenomenon is also known as extirpation. Local extinctions are contrasted with global extinctions.

Local extinctions may be followed by a replacement of the species taken from other locations; wolf reintroduction
Wolf reintroduction

Wolf reintroduction involves the artificial reestablishment of a population of gray wolf into areas where they had been previously Extirpation....
 is an example of this.

Conservation


Local extinctions mark a change in the ecology
Ecology

Ecology is the science study of the distribution and Abundance of life and the interactions between organisms and their nature environment ....
 of an area.

The area of study chosen may reflect a natural subpopulation, political boundaries, or both. The Cetacean Specialist Group of the IUCN has assessed the threat of a local extinction of the Black Sea
Black Sea

The Black Sea is an inland sea sea bounded by southeastern Europe, the Caucasus and the Anatolia and is ultimately connected to the Atlantic Ocean via the Mediterranean Sea and Aegean Seas and various straits....
 stock of Harbour Porpoise
Harbour Porpoise

The Harbor Porpoise is one of six species of porpoise. It is one of the smallest ocean mammals. As its name implies, it stays close to coastal areas or river estuaries and as such is the most familiar porpoise to whale-watching....
 (Phocoena phocoena) which touches six different countries. COSWIC, by contrast, investigate wildlife only in Canada, so assesses only the risk of a Canadian local extinction even for species which cross into the United States or other countries. Other subpopulations may be naturally divided by political or country boundaries.

Often a subpopulation of a species will also be a subspecies
Subspecies

In biology, subspecies is the taxonomic rank immediately subordinate to a species. A subspecies is a taxonomic group which is less distinct than the Common descent or species from which it originates....
. For example, the recent disappearance of the Black Rhinoceros
Black Rhinoceros

The Black Rhinoceros , also colloquially Black Rhino, is a species of rhinoceros, native to the eastern and central areas of Africa including Kenya, Tanzania, Cameroon, South Africa, Namibia and Zimbabwe....
 (Diceros bicornis) from Cameroon
Cameroon

The Republic of Cameroon is a unitary state of central and western Africa. It is bordered by Nigeria to the west; Chad to the northeast; the Central African Republic to the east; and Equatorial Guinea, Gabon, and the Republic of the Congo to the south....
 spells not only the local extinction of rhinoceroses in Cameroon, but also the global extinction of the Western Black Rhinoceros
Western Black Rhinoceros

The Western Black Rhinoceros or West African Black Rhinoceros was the rarest of the Black Rhino subspecies, and on 7 July 2006, it was tentatively declared extinct....
 (Diceros bicornis longipes).

In at least one case, scientists have found a local extinction useful for research: In the case of the Bay Checkerspot, scientists, including Paul R. Ehrlich
Paul R. Ehrlich

Paul Ralph Ehrlich is an United States entomologist specializing in Lepidoptera . He became a household name after publication of his 1968 book The Population Bomb, in which he predicted that "In the 1970s and 1980s ....
, chose not to intervene in a local extinction, using it to study the danger to the world population However, similar studies are not carried out where a global population is at risk.

IUCN subpopulation and stock assessments

While the World Conservation Union
World Conservation Union

The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to natural resource Conservation ethic....
 (IUCN) mostly only categorizes whole species or subspecies, assessing the global risk of extinction, in some cases it also assesses the risks to stocks and populations, especially to preserve genetic diversity. In all, 119 stocks or subpopulations across 69 species have been assessed by the IUCN in 2006.

Examples of stocks and populations assessed by the IUCN for the threat of local extinction:
  • Marsh Deer
    Marsh Deer

    The Marsh Deer, Blastocerus dichotomus , is the largest deer species from South America reaching a length of 2 meters and a height of 1.2 meters at the rump....
     (three subpopulations assessed)
  • Blue Whale
    Blue Whale

    The Blue Whale is a marine mammal belonging to the suborder of baleen whales . At up to 32.9 metres in length and 172 metric tonnes or more in weight, it is the largest whale and the largest living animal and is believed to be the largest organism ever to have existed....
    , North Pacific stock and North Atlantic stock
  • Bowhead Whale
    Bowhead Whale

    The Bowhead Whale , also known as Greenland Right Whale or Arctic Whale, is a baleen whale of the right whale family Balaenidae. A stocky dark-colored whale without a dorsal fin, it can grow to 20 meters in length....
    , Balaena mysticetus (five subpopulations assessed), from Critically Endangered to LR/cd
  • Lake Sturgeon
    Lake sturgeon

    The lake sturgeon is a North American temperate fresh water fish, one of about 20 species of sturgeon. Like other sturgeons, this species is an evolutionarily ancient bottomfeeder with a partly cartilage skeleton and skin bearing rows of bony plates....
    , Acipenser fulvescens, Mississippi & Missouri Basins subpopulation assessed as Vulnerable
    Vulnerable species

    A vulnerable species is a species which is likely to become Endangered species unless the circumstances threatening its survival and reproduction improve....
  • Wild Common carp
    Common carp

    The Common carp or European carp is a widespread freshwater fish most closely related to the common goldfish , with which it is capable of Hybrid ....
    , Cyprinus carpio (River Danube subpopulation)
  • Black-footed Rock Wallaby Petrogale lateralis (MacDonnell Ranges subpopulation and Western Kimberly subpopulation)


The IUCN also lists countries where assessed species, subspecies or subpopulations are found, and from which countries they have been extirpated or reintroduced.

The IUCN has only three entries for subpopulations which have become extinct the Aral Sea
Aral Sea

The Aral Sea is a landlocked endorheic basin in Central Asia; it lies between Kazakhstan in the north and Karakalpakstan, an autonomous region of Uzbekistan, in the south....
 stock of Ship sturgeon (Acipenser nudiventris); the Adriatic Sea
Adriatic Sea

The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges....
 stock of Beluga
Beluga sturgeon

The beluga or European sturgeon is a species of anadromous fish in the sturgeon family of order Acipenseriformes. It is found primarily in the Caspian Sea and Black Sea basins, and occasionally in the Adriatic Sea....
 (Huso huso); and the Mexican subpopulation of Wolf (Canis lupus) which is extinct in the wild. No plant or fungi subpopulations have been assessed by the IUCN.

Local extinction events


Major environmental events, such as volcanic eruptions, may lead to large numbers of local extinctions, such as with the 1980 Mount St. Helens eruption, which led to a fern spike
Fern spike

In paleontology, a fern spike is the occurrence of abundant fern spores in the fossil record, usually immediately after an extinction event. The spikes are believed to represent a large, temporary increase in the number of ferns relative to other terrestrial plants after the extinction or thinning of the latter, probably because fern Biolog...
.

Metapopulation


'Metapopulation' is a concept in population biology
Population biology

Population biology is a study of biological populations of organisms, especially in terms of biodiversity, evolution, and Ecology. The term population biology is often used interchangeably with population ecology, although the term with biology is more frequently used when studying diseases, viruses, and microbes, and the term with ecolo...
 that involves frequent local extinction (extirpation) and recolonization as part of a natural process. A metapopulation consists of a group of patches of suitable habitat, some of which have a species present and others do not. These small populations may fail, and eventually be recolonized by immigrants from other patches. This complex immigration/extinction dynamic allows metapopulations to thrive where individual habitat patches are too small to permanently sustain a population. This is in contrast to most cases of habitat fragmentation
Habitat fragmentation

Habitat fragmentation is a process of Natural environmental change important in evolution and conservation biology. As the name implies, it describes the emergence of discontinuities in an organism's preferred environment ....
 into patches, or worse, local extinction because recolonization or sufficient immigration is unlikely. When habitat become fragmented through development, succession, etc., the patches may become too small to sustain a healthy population, however migration between patches is difficult. Thus, there would be little chance of recolonization, as in a metapopulation, and local extinction would be a serious problem, rather than an natural fluctuation in a healthy larger population.

See also

  • Extinction
    Extinction

    In biology and ecology, extinction is the death of every member of a species or group of taxon. The moment of extinction is generally considered to be the death of the last individual of that species ....
  • List of extinct animals
    List of extinct animals

    Pre-modern* List of dinosaurs* List of pterosaurs* List of plesiosaurs* List of ichthyosaurs* Hominidae...
  • Threatened species
    Threatened species

    Threatened species are any species which are vulnerable to extinction in the near future.World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories: Vulnerable species, endangered species, and Critically endangered species, depending...


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