Extinction
hideIn biology and ecology, extinction is the end of a species or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species (although the capacity to breed and recover may have been lost before this point). Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "re-appears" (typically in the fossil record) after a period of apparent absence.
Through evolution, new species arise through the process of speciation—where new varieties of organisms arise and thrive when they are able to find and exploit an ecological niche—and species become extinct when they are no longer able to survive in changing conditions or against superior competition. A typical species becomes extinct within 10 million years of its first appearance, although some species, called living fossils, survive virtually unchanged for hundreds of millions of years. Extinction, though, is usually a natural phenomenon; it is estimated that 99.9% of all species that have ever lived are now extinct.
Prior to the dispersion of humans across the earth, extinction generally occurred at a continuous low rate, mass extinctions being relatively rare events. Starting approximately 100,000 years ago, and coinciding with an increase in the numbers and range of humans, species extinctions have increased to a rate unprecedented since the Cretaceous–Tertiary extinction event. This is known as the Holocene extinction event and is at least the sixth such extinction event. Some experts have estimated that up to half of presently existing species may become extinct by 2100.
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News tagged with extinction
Researchers reveal ancient origins of modern opossum
Other Sciences / Archaeology & Fossils
15 hours ago |
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A University of Florida researcher has co-authored a study tracing the evolution of the modern opossum back to the extinction of the dinosaurs and finding evidence to support North America as the center of ...
Late-surviving megafauna exposed by ancient DNA in frozen soil
Dec 15, 2009 |
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Extinct woolly mammoths and ancient American horses may have been grazing the North American steppe for several thousand years longer than previously thought. After plucking ancient DNA from frozen soil in ...
Sucker-footed bats don't use suction after all (w/ Video)
Dec 14, 2009 |
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There are approximately 1,200 species of bats worldwide. Of that total, only six are known to roost with their heads pointed upward. Investigators did not know why, because they knew next to nothing about ...
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US-China showdown still looms over climate talks
Dec 15, 2009 |
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(AP) -- In a showdown between the world's two largest polluters, China accused the United States and other rich nations Tuesday of backsliding on fighting global warming and the top U.S. envoy said Chinese ...
Nearly 100 new species described by California Academy of Sciences in 2009
Dec 14, 2009 |
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In 2009, researchers at the California Academy of Sciences added 94 new relatives to our family tree. The new species include 65 arthropods, 14 plants, eight fishes, five sea slugs, one coral, and one fossil ...
The mammoths' swan song revised
Other Sciences / Archaeology & Fossils
Dec 14, 2009 |
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This is shown by samples of ancient DNA, analysed by an international team of research scientists under the leadership of Professor Eske Willerslev from Copenhagen University. Analyses of ancient DNA thereby ...
Good dentistry may have saved the dinosaurs
Other Sciences / Archaeology & Fossils
Dec 14, 2009 |
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Infectious diseases can be transmitted by sneezing, touching, or - for Tasmanian devils - biting each other on the face, a habit that may have driven the dinosaurs to extinction through the transmission of a protozoan parasite.
Efforts to save endangered languages
Other Sciences / Social Sciences
Dec 14, 2009 |
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(PhysOrg.com) -- There are an estimated 6,500 languages in the world, with around fifty percent of them endangered and likely to cease to exist by 2100, but efforts are now being made to save them from extinction.
Koalas, penguins at risk of extinction: study
Dec 14, 2009 |
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Climate change threatens the survival of dozens of animal species from the emperor penguin to Australian koalas, according to a report released Monday at the UN climate summit.
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