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Local extinction, also known as extirpation, is the condition of a species (or other taxon), plants or animals, that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions.
Local extinctions mark a change in the ecology 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 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 stock of harbour porpoise (Phocoena phocoena) that touches six countries. COSEWIC, by contrast, investigates wildlife only in Canada, so assesses only the risk of a Canadian local extinction even for species that cross into the United States or other countries. Other subpopulations may be naturally divided by political or country boundaries.
Many crocodilian species have experienced localized extinction, particularly the saltwater crocodile (Crocodylus porosus), which has been extirpated from Vietnam, Thailand, Java, and many other areas.
Often a subpopulation of a species will also be a subspecies. For example, the recent disappearance of the black rhinoceros (Diceros bicornis) from Cameroon 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 butterfly, scientists, including Paul R. Ehrlich, 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.
Wolves have been a species that have been reintroduced into their historical range. This has happened with red wolves (Canis lupus rufus) 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. Reintroduction of wolves is a controversial subject and there are pro's and con's on each side.
IUCN subpopulation and stock assessmentsEdit
While the World Conservation Union (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 (three subpopulations assessed)
- Blue whale, North Pacific stock and North Atlantic stock
- Bowhead whale, Balaena mysticetus (five subpopulations assessed), from critically endangered to LR/cd
- Lake sturgeon, Acipenser fulvescens, Mississippi & Missouri Basins subpopulation assessed as vulnerable
- Wild common carp, Cyprinus carpio (River Danube subpopulation)
- Black-flanked 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 that have become extinct the Aral Sea stock of Ship sturgeon (Acipenser nudiventris); the Adriatic Sea stock of beluga sturgeon (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 eventsEdit
Heat waves can lead to local extinction. In New Zealand, during the summer of 2017–2018, sea surface temperatures around parts of South Island exceeded 23 °C (73 °F), which was well above normal. Air temperatures were also high, exceeding 30 °C (86 °F). 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, Astyanax fasciatus, and Characidium zebra. This could be caused by the introduction of non-native species, like Talapia rendalli, into the lagoon, changes in water level and organic pollution.
Glaciation can lead to local extinction. This was the case during the Pleistocene glaciation 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.
- Ladle, Richard; Whittaker, Robert J., eds. (2011). Conservation Biogeography. John Wiley & Sons. p. 61. ISBN 978-1-4443-9811-3.
- Smith-Patten, Brenda D.; Bridge, Eli S.; et al. (14 January 2015). "Is extinction forever?". Public Understanding of Science. 24 (4): 481–495. doi:10.1177/0963662515571489. PMC 4404403. PMID 25711479.
- Webb, Grahame; Manolis, S; Brien, Matthew (2010). Saltwater Crocodile Crocodylus porosus (PDF). Crocodiles. pp. 99–113.[dead link]
- Holsinger, Kent. "Local extinction Archived 2007-03-11 at the Wayback Machine". Population Viability Analysis: Bay Checkerspot Butterfly. URL accessed August 11, 2006.
- Arts, Koen; Fischer, Anke; Wal, René van der (2016). "Boundaries of the wolf and the wild: a conceptual examination of the relationship between rewilding and animal reintroduction". Restoration Ecology. 24 (1): 27–34. doi:10.1111/rec.12309. ISSN 1526-100X.
- IUCN Red List, search for only stocks and subpopulations [dead link]
- IUCN Red List, search for extinct stocks and populations:  Archived 2018-12-09 at the Wayback Machine
- Thomsen, Mads S.; Mondardini, Luca; Alestra, Tommaso; Gerrity, Shawn; Tait, Leigh; South, Paul M.; Lilley, Stacie A. & Schiel, David R. (March 2019). "Local Extinction of Bull Kelp (Durvillaea spp.) Due to a Marine Heatwave". Frontiers in Marine Science. 6. doi:10.3389/fmars.2019.00084. ISSN 2296-7745.
- Pompeu, Paulo dos Santos; Alves, Carlos Bernardo Mascarenhas (December 2003). "Local fish extinction in a small tropical lake in Brazil". Neotropical Ichthyology. 1 (2): 133–135. doi:10.1590/S1679-62252003000200008. ISSN 1679-6225.
- Gates, G. E. (May 1949). "Miscellanea Megadrilogica". The American Naturalist. 83 (810): 139–152. doi:10.1086/281596. ISSN 0003-0147. S2CID 222328616.