Local extinction is the condition of a 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. While in many cases this definition is adequate, more precise or differing measures are often used, such as similarity of DNA, morphology or (or other taxon A taxon is a group of (one or more) organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement. Defining what belongs or does not belong to such a taxonomic group is done by a taxonomist. It is not uncommon for one taxonomist to disagree with another on what exactly belongs to) which 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 involves the artificial reestablishment of a population of wolves into areas where they had been previously extirpated. Wolf reintroduction is only considered where large tracts of suitable wilderness still exist and where certain prey species are abundant enough to support a predetermined wolf population is an example of this.
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Conservation
Local extinctions mark a change in the ecology Ecology is the scientific study of the distributions, abundance and relations of organisms and their interactions with the environment. Ecology includes the study of plant and animal populations, plant and animal communities and ecosystems. Ecosystems describe the web or network of relations among organisms at different scales of organization 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 The Black Sea is an inland sea bounded by Europe, Anatolia and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and Aegean Seas and various straits. The Bosphorus strait connects it to the Sea of Marmara, and the strait of the Dardanelles connects it to the Aegean Sea region of the Mediterranean. These waters stock of Harbour Porpoise The Harbour Porpoise is one of six species of porpoise. It is one of the smallest marine mammals. As its name implies, it stays close to coastal areas or river estuaries and as such is the most familiar porpoise to whale watchers. This porpoise often ventures up rivers and has been seen hundreds of miles from the sea (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 biological classification, is either a taxonomic rank subordinate to species, or a taxonomic unit in that rank (plural: subspecies). A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one. For example, the recent disappearance of the Black Rhinoceros The Black Rhinoceros or Hook-lipped Rhinoceros , is a species of rhinoceros, native to the eastern and central areas of Africa including Kenya, Tanzania, Cameroon, South Africa, Namibia, Zimbabwe, and Angola. Although the Rhino is referred to as black, it is actually more of a grey/brown/white color in appearance (Diceros bicornis) from Cameroon The Republic of Cameroon is a country 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. Cameroon's coastline lies on the Bight of Bonny, part of the Gulf of Guinea and the Atlantic Ocean spells not only the local extinction of rhinoceroses in Cameroon, but also the global extinction of the Western Black Rhinoceros (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 Ralph Ehrlich is an American biologist and educator who is the Bing Professor of Population Studies in the department of Biological Sciences at Stanford University and president of Stanford's Center for Conservation Biology.. By training he is an entomologist specializing in Lepidoptera (butterflies), but he is better known as an ecologist, chose not to intervene in a local extinction, using it to study the danger to the world population.[1] However, similar studies are not carried out where a global population is at risk.
IUCN subpopulation and stock assessments
While the World Conservation Union The International Union for Conservation of Nature is an international organization dedicated to natural resource conservation. It helps the world find pragmatic solutions to our most pressing environment and development challenges (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.[2]
Examples of stocks and populations assessed by the IUCN for the threat of local extinction:
- 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. It is found in Argentina, Bolivia, Brazil, Uruguay and Paraguay. Formerly found through all of tropical South America today it is reduced to small isolated populations at marsh and lagoon (three subpopulations assessed)
- Blue Whale The Blue whale is a marine mammal belonging to the suborder of baleen whales (called Mysticeti). At over 33 metres (108 ft) in length and 180 metric tons (200 short tons) or more in weight, it is the largest animal ever known to have existed, North Pacific stock and North Atlantic stock
- Bowhead Whale The bowhead whale is a baleen whale of the right whale family Balaenidae in suborder Mysticeti. A stocky dark-colored whale without a dorsal fin, it can grow to 20 meters (66 ft) in length. Estimated maximum weight of this thick-bodied species is 136 tonnes (134 LT; 150 ST), second only to the blue whale, although the bowhead's maximum length is, Balaena mysticetus (five subpopulations assessed), from Critically Endangered to LR/cd
- Lake Sturgeon, Acipenser fulvescens, Mississippi & Missouri Basins subpopulation assessed as Vulnerable A vulnerable species is a species which is likely to become endangered unless the circumstances threatening its survival and reproduction improve. The following is a very small, non-representative fraction of the 8,566 species listed as vulnerable on the IUCN Red List
- Wild Common carp The Common carp is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia. The wild populations are considered vulnerable to extinction, but the species has also been domesticated and introduced into environments worldwide, and is often considered an invasive species. It gives its name to the carp family, 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[3] the Aral Sea The Aral Sea is a saline endorheic basin in Central Asia; it lies between Kazakhstan (Aktobe and Kyzylorda provinces) in the north and Karakalpakstan, an autonomous region of Uzbekistan, in the south. The name roughly translates as "Sea of Islands", referring to more than 1,500 islands that once dotted its waters stock of Ship sturgeon (Acipenser nudiventris); the 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. The Adriatic Sea is a part of the Mediterranean Sea stock of Beluga The beluga or European sturgeon is a species of anadromous fish in the sturgeon family (Acipenseridae) of order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, and occasionally in the Adriatic Sea. Heavily fished for the female's valuable roe—known as beluga caviar— the beluga is a huge (some documented specimens (Huso huso); and the Mexican In Pre-Columbian Mesoamerica many cultures matured into advanced civilizations such as the Olmec, the Toltec, the Teotihuacan, the Zapotec, the Maya and the Aztec before the first contact with Europeans. In 1521, Spain conquered and colonized the territory, which was administered as the viceroyalty of New Spain which would eventually become Mexico subpopulation of Wolf The grey wolf , often known simply as the wolf, is the largest wild member of the Canidae family. Though once abundant over much of Eurasia and North America, the grey wolf inhabits a reduced portion of its former range due to widespread destruction of its territory, human encroachment, and the resulting human-wolf encounters that sparked broad (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.
See also
- Extinction In biology and ecology, extinction is the end of an organism or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species . Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena
- List of extinct animals
- Threatened species Threatened species are any species which are vulnerable to extinction in the near future. World Conservation Union (IUCN) is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories: vulnerable, endangered, and critically endangered, depending on the degree to which
External links
- ^ Holsinger, Kent. "Local extinction". Population Viability Analysis: Bay Checkerspot Butterfly. URL accessed August 11, 2006.
- ^ IUCN Red List The IUCN Red List of Threatened Species , founded in 1948, is the world's most comprehensive inventory of the global conservation status of plant and animal species. The International Union for the Conservation of Nature and Natural Resources (IUCN) is the world's main authority on the conservation status of species. A series of Regional Red Lists, search for only stocks and subpopulations [1]
- ^ IUCN Red List The IUCN Red List of Threatened Species , founded in 1948, is the world's most comprehensive inventory of the global conservation status of plant and animal species. The International Union for the Conservation of Nature and Natural Resources (IUCN) is the world's main authority on the conservation status of species. A series of Regional Red Lists, search for extinct stocks and populations: [2]
Categories: Extinction Categories: Evolutionarily significant biological phenomena | Death | Ecology | Paleontology
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