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In biology and ecology, extinction is the disappearance of a species or group of species. The moment of extinction is generally considered to be the death of the last individual of that species. In species which reproduce sexually, extinction of a species is generally inevitable when there is only one individual of that species left, or only individuals of a single sex. Extinction is not an unusual event in geological time—species are created by speciation, and disappear through extinction.

Currently, many environmental groups and governments are worried about extinction of species due to human intervention. Reasons for the possible extinctions include pollution, destruction of habitat, and introduction of new predators. Endangered species are species that are in danger of becoming extinct. Extinct in the wild is a term often used for species which no longer exist in the wild, but only in captivity.

1 Mass extinctions

There have been periodic mass extinctions, in which many species have disappeared in a relatively short period of geological time. These are covered in more detail in the article on extinction events. The most recent of these, the K-T extinction at the end of the Cretaceous period, is best known for having wiped out the dinosaurs.

Some also believe that we are currently in a period of mass extinction right now, the Holocene extinction event. While there is no room to doubt that human activity has increased the rate of species extinction worldwide, however, the exact extent of anthropogenic extinction remains controversial.

See: The Sixth Extinction : Patterns of Life and the Future of Humankind by Richard Leakey ( BooksEnthsiast.com ).

Mass extinctions are a key part of the punctuated equilibrium hypothesis of Stephen Jay GouldStephen Jay Gould ( September 10, 1941 May 20, 2002) was a New York-born American paleontologist, an evolutionary biologist and historian of science. He was the most influential and widely-read writer of research-based popular science of his generation. and Niles Eldredge . See: Time Frames: The Evolution of Punctuated Equilibria ( BooksEnthsiast.com )

2 Is extinction permanent?

Until recently, it had been thought that the extinction of an animal meant the end of its time on Earth, however, it has been hypothesized that through the process of cloningCloning is the process of creating an identical copy of an original. A clone in the biological sense, therefore, is a multi-cellular organism that is genetically identical to another living organism. Sometimes this can refer to "natural" clones made eithe, extinct species may be "brought back to life." Early targets for cloning have been the mammothA mammoth is any of a number of an extinct genus of elephant, often with long curved tusks and, in northern species, a covering of long hair. They inhabited the northern regions of the world, in Europe, northern Asia, and North America. Many types of mamm and thylacineThe Tasmanian Tigers is the name of the Tasmanian state cricket team. The Thylacine Thylacinus cynocephalus was a large carnivorous marsupial native to Australia. In the early days of European settlement it was known as the Tasmanian Tiger or Tasmanian Wo, however no extinct species have yet been cloned. Given the generalized lack of success in cloning even still living species, it would certainly be premature to declare anything other than "extinction is forever".

3 See also

CoextinctionCoextinction of a species is the loss of one species upon the extinction of another. The term was originally used in the context of the extinction of parasitic insects following the loss of their hosts. The term is now used describe the subsequent loss of
List of extinct animalsPrehistoric extinctions A large number of historical orders are extinct, e. dinosaurs, pterosaurs and ammonites, probably wiped out by meteor or asteroid strikes, in various Epochs. Historic extinctions Pleistocene Megafauna Common Era Extinctions ( Mamma
The Skeptical EnvironmentalistThe Skeptical Environmentalist is a controversial book by political scientist Bjorn Lomborg which argues that claims made by environmentalists about global warming, overpopulation, energy, deforestation, species loss, water shortages, and a variety of oth
BiodiversityBiodiversity or biological diversity is a neologism and a portmanteau word, from bio and diversity. It is the diversity of and in living nature. Diversity, at its heart, implies the number of different kinds of objects, such as species. However, defining
Unified neutral theory of biodiversity

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Topics: Extinction Species Extinct Extinctions Mass Time Cloning Life...

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ExtinctionIn biology and ecology, extinction is the disappearance of a species or group of species. The moment of extinction is generally considered to be the death of the last individual of that species. In species which reproduce sexually, extinction of a species	Extinct Australian animalsFollowing is an incomplete list of Australian vertebrate extinctions from 1788 to the present, in the format: Common name, Latin name habitat, estimated date of extinction, probable main causes (listed, where possible, with the most significant causes fir	Extinct languageAn extinct language is a language which is no longer natively spoken. One of the most well known extinct languages is Latin. See also: Last native speakers Endangered language List of extinct languages.
Extinction Level Event (Final World Front)	Extinction (disambiguation)	Extinction (ENT)

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