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Local extinction, also known as extirpation, refers to 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 appropriat ...
(or other
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 plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the Endling, last individual of the species, although the Functional ext ...
s. Local extinctions mark a change in the
ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overl ...
of an area. In recent times, local extinction has sometimes been followed by a replacement of the species taken from other locations; wolf reintroduction is an example of this. The term "local extinction" is highly vernacular. The more proper biological term is ''extirpation''.


Discussion

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 ...
can lead to local extinction. This was the case during the
Pleistocene glaciation The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial and interglacial periods during the Quaternary period that began 2.58 Ma (million years ago) and is ongoing. Although geologists describe ...
event in North America. During this period, most of the native North American species of earthworm were killed in places covered by glaciation. This left them open for colonization by European earthworms brought over in soil from Europe. Species naturally become extirpated from islands over time. The number of species an island can support is limited by its geographical size. Because many islands were relatively recently formed due to climate change at the end of the Pleistocene when the sea level rose, and these islands most likely had the same complement of species as found on the mainland, counting the species which still survive at present on a statistically large enough amount of islands will give the parameters with which certain groups of species such as plants or birds will become less biodiverse on a given island over a given period of time, depending on its size. The same calculations can also be applied to determine when species will disappear from nature parks ('islands' in many senses), mountain tops and mesas (see
sky island 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 s ...
s), forest remnants or other such distributional patches. This research also demonstrates that certain species are more prone to extinction than others, a species has an intrinsic extinction-ability (incidence function). Some species exploit or require transient or disturbed habitats, such as vernal pools, a human gut, or burnt woodland after
forest fire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identi ...
s, and are characterised by highly fluctuating population numbers and shifting distributional patterns. Many natural ecosystems cycle through a standard
succession Succession is the act or process of following in order or sequence. Governance and politics *Order of succession, in politics, the ascension to power by one ruler, official, or monarch after the death, resignation, or removal from office of ...
,
pioneer species Pioneer species are hardy species that are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by wildfire. Pioneer flora Some lichens grow on rocks without soil, so ...
disappear from a region as the ecosystem matures and reaches a
climax community In scientific ecology, climax community or climatic climax community is a historic term for a community of plants, animals, and fungi which, through the process of ecological succession in the development of vegetation in an area over time, hav ...
. A local extinction can be useful for research: in the case of the
Bay checkerspot butterfly The Bay checkerspot (''Euphydryas editha bayensis'') is a butterfly endemic to the San Francisco Bay region of the U.S. state of California. It is a federally threatened species, as a subspecies of '' Euphydryas editha''. Since the 1980s the ...
, scientists, including Paul R. Ehrlich, chose not to intervene as a population disappeared from an area in order to study the process.Holsinger, Kent.
Local extinction
". ''Population Viability Analysis: Bay Checkerspot Butterfly''. URL accessed August 11, 2006.
Many crocodilian species have experienced localized extinction, particularly the
saltwater crocodile The saltwater crocodile (''Crocodylus porosus'') is a crocodilian native to saltwater habitats and brackish wetlands from India's east coast across Southeast Asia and the Sundaic region to northern Australia and Micronesia. It has been l ...
(''Crocodylus porosus''), which has been extirpated from Vietnam, Thailand, Java, and many other areas. Major environmental events, such as volcanic eruptions, may lead to large numbers of local extinctions, such as with the
1980 Mount St. Helens eruption On March 27, 1980, a series of volcanic explosions and pyroclastic flows began at Mount St. Helens in Skamania County, Washington, United States. A series of phreatic blasts occurred from the summit and escalated until a major explosive eru ...
, which led to a fern spike extinction. Heat waves can lead to local extinction. In New Zealand, during the summer of 2017–2018, sea surface temperatures around parts of
South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...
exceeded , which was well above normal. Air temperatures were also high, exceeding . These high temperatures, coupled with small wave height, led to the local extinction of Bull Kelp (''Durvillaea'' spp.) from Pile Bay. Lagoa Santa, Brazil has lost almost 70% of the local fish species over the last 150 years. These include ''
Acestrorhynchus lacustris ''Acestrorhynchus lacustris'' is a species of fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, ...
'', ''
Astyanax fasciatus In Greek mythology, Astyanax (; grc, Ἀστυάναξ ''Astyánax'', "lord of the city") was the son of Hector, the crown prince of Troy, and his wife, Princess Andromache of Cilician Thebe."Astyanax". ''Oxford Classical Dictionary''. Oxford ...
'', and ''
Characidium zebra ''Characidium'' is a genus of fish in the family Crenuchidae (South American darters). They are mainly found in South America, but ''C. marshi'' is from Panama. They are small (less than long), slender fish that live on the bottom in flowing f ...
''. This could be caused by the introduction of non-native species, like '' Talapia rendalli'', into the lagoon, changes in water level and organic pollution. Local extinctions can be reversed, in some cases artificially. Wolves are a species that have been reintroduced into parts of their historical range. This has happened with red wolves (''
Canis rufus The red wolf (''Canis rufus'') is a canine native to the southeastern United States. Its size is intermediate between the coyote (''Canis latrans'') and gray wolf (''Canis lupus''). The red wolf's taxonomic classification as being a separate s ...
'') in the United States in the late 1980s and also grey wolves in Yellowstone National Park in the mid-1990s. There have been talks of reintroducing wolves in Scotland, Japan, and Mexico.


Subpopulations and stocks

When the local population of a certain species disappears from a certain geographical delimitation, whether fish in a drying pond or an entire ocean, it can be said to be extirpated or locally extinct in that pond or ocean. A particular total world population can be more or less arbitrarily divided into 'stocks' or 'subpopulations', defined by political or other geographical delimitations. For example, the Cetacean Specialist Group of the
International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
(IUCN) has assessed the conservation status of the
Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Rom ...
stock of harbour porpoise (''Phocoena phocoena'') that touches six countries, and COSEWIC, which only assesses the conservation status of wildlife in Canada, even assesses Canadian species that occur in the United States or other countries. While the IUCN mostly only assesses the global conservation status of species or subspecies, in some older cases it also assessed the risks to certain stocks and populations, in some cases these populations may be genetically distinct. In all, 119 stocks or subpopulations across 69 species had been assessed by the IUCN in 2006.
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biolo ...
, search for only stocks and subpopulation

/ref> If a local stock or population becomes extinct, the species as a whole has not become extinct, but extirpated from that local area. Examples of stocks and subdivisions of world populations assessed separately by the IUCN for their conservation status are: * Marsh deer (three populations assessed) *
Blue whale The blue whale (''Balaenoptera musculus'') is a marine mammal and a baleen whale. Reaching a maximum confirmed length of and weighing up to , it is the largest animal known to have ever existed. The blue whale's long and slender body can ...
, North Pacific and North Atlantic stocks *
Bowhead whale The bowhead whale (''Balaena mysticetus'') is a species of baleen whale belonging to the family Balaenidae and the only living representative of the genus '' Balaena''. They are the only baleen whale endemic to the Arctic and subarctic waters, a ...
, ''Balaena mysticetus'' (five populations assessed, from critically endangered to LR/cd) * Lake sturgeon, ''Acipenser fulvescens'', Mississippi & Missouri Basins population assessed as vulnerable * Wild
common carp The Eurasian carp or European carp (''Cyprinus carpio''), widely known as the common carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Arkive The ...
, ''Cyprinus carpio'' (distribution in the River Danube) * Black-flanked rock-wallaby ''Petrogale lateralis'' (
MacDonnell Ranges The MacDonnell Ranges, or Tjoritja in Arrernte, is a mountain range located in southern Northern Territory. MacDonnell Ranges is also the name given to an interim Australian bioregion broadly encompassing the mountain range, with an area of .< ...
population and Western Kimberly population) The IUCN also lists countries where assessed species, subspecies or geographic populations are found, and from which countries they have been extirpated or reintroduced.


See also

* List of extinct animals *
Threatened species Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of '' critical depen ...
*
Extinct in the wild A species that is extinct in the wild (EW) is one that has been categorized by the International Union for Conservation of Nature as known only by living members kept in captivity or as a naturalized population outside its historic range due t ...


References

{{DEFAULTSORT:Local Extinction Extinction