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Encyclopedia > Functional extinction
Conservation status
the risk of extinction
Extinction

Extinct
Functionally Extinct
Extinct in the Wild
The conservation status of a species is an indicator of the likelihood of that species continuing to survive. ... The Dodo, shown here in illustration, is an often-cited[1] example of extinction. ... The Dodo, shown here in illustration, is an often-cited[1] example of extinction. ...

Threatened

Critically Endangered
Endangered
Vulnerable
An endangered species is a species whose population is so small that it is in danger of becoming extinct. ... The critically endangered Amur Tiger, a rare subspecies of tiger. ... A vulnerable species is one whose chances of extinction characterize it as threatened but not quite as endangered. ...

Lower risk

Near Threatened
Conservation Dependent
Least Concern
Near Threatened (NT) is an IUCN category assigned to species or lower taxa which may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status. ... Conservation Dependent (LR/cd) was an IUCN category assigned to species or lower taxa which were dependent on conservation efforts to prevent the taxon becoming threatened with extinction. ... Least concern (LC) is an IUCN category assigned to species or lower taxa which do not qualify for any other category. ...

See also

World Conservation Union
IUCN Red List
The World Conservation Union or International Union for Conservation of Nature and Natural Resources (IUCN) is an international organization dedicated to natural resource conservation. ... The IUCN Red List of Threatened Species (also known as the IUCN Red List and Red Data List), created in 1963, is the worlds most comprehensive inventory of the global conservation status of plant and animal species. ...

Functional extinction is the extinction of a species or other taxon, as measured by one of the following: The Dodo, shown here in illustration, is an often-cited[1] example of extinction. ... In biology, a species is one of the basic units of biodiversity. ... A taxon (plural taxa), or taxonomic unit, is a grouping of organisms (named or unnamed). ...

  1. it disappears from the fossil record, or historic reports of its existence cease; or[1]
  2. the population is reduced to an extent that it no longer plays a significant role in ecosystem function[2]; or
  3. the population is no longer viable. That is, when there are no individuals left with potential to reproduce, or when the small population of breeding individuals will not be able to sustain itself simply due to inevitable inbreeding depression and genetic drift, which leads to a loss of fitness.

In plant populations, self-incompatibility mechanisms may cause related plant specimens to be incompatible, which may lead to functional extinction if an entire population becomes self incompatible. This is a situation which does not occur in larger populations. It has been suggested that this article or section be merged into Fossil. ... An ecosystem, a contraction of ecological and system, refers to the collection of components and processes that comprise, and govern the behavior of, some defined subset of the biosphere. ... Inbreeding Depression is reduced fitness in a given population as a result of breeding of related individuals. ... Genetic drift is the term used in population genetics to refer to the statistical drift over time of allele frequencies in a finite population due to random sampling effects in the formation of successive generations. ... Fitness (often denoted in population genetics models) is a central concept in evolutionary theory. ... Self-incompatibility (SI) is one of the most important means to prevent selfing and promote the generation of new genotypes in plants, and it is considered as one of the causes for the spread and success of the angiosperms, on our planet. ...


In polygyous populations, where only a few males leave offspring, there is a much smaller reproducing population than if all viable males were considered. Further, the successful males act as a genetic bottleneck, leading to more rapid genetic drift or problems with inbreeding in small populations. The term polygyny (neo-Greek: poly+gune Many + Wives) is used in related ways in social anthropology and sociobiology. ...


Under the IUCN Red List categories, a functionally extinct species, which has had no recent sightings, may be classified as critically endangered unless there is no reasonable doubt that the last individual has died, such as through extensive surveys. Alternatively, it may be classified as being extinct in the wild if specimens remain in captivity and there is no reasonable doubt that the last wild specimen has died. The IUCN Red List of Threatened Species (also known as the IUCN Red List and Red Data List), created in 1963, is the worlds most comprehensive inventory of the global conservation status of plant and animal species. ... An endangered species is a species whose population is so small that it is in danger of becoming extinct. ...


See also

Conservation genetics is a science that aims to apply genetic methods to deal with the maintenance, loss, and restoration of biodiversity. ... Mutational meltdown refers to the process by which a small population accumulates deleterious mutations, which leads to loss of fitness and decline of the population size, which leads to further accumulation of deleterious mutations. ... Species with a small population size are subject to a higher chance of extinction because their small population size makes them more vulnerable to genetic drift, resulting in stochastic variation in their gene pool, their demography and their environment. ...

References

  1. ^ Extinctions in Near Time: Causes, Contexts, and Consequences 1999. Edited by R.D.E. MacPhee, Hans-Dieter Sues. page 202.
  2. ^ What is the link between biodiversity and ecosystem services?. Scientific Facts on Biodiversity. Retrieved on 2006-12-16.

 
 

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