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
Antarctica served as climatic refuge in Earth's greatest extinction event
Space & Earth / Earth Sciences
Dec 02, 2009 |
4.6 / 5 (10) |
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A new fossil species suggests that some land animals may have survived the end-Permian extinction by living in cooler climates in Antarctica. Researchers have identified a distant relative of mammals that apparently survived ...
Superior Super Earths
Space & Earth / Space Exploration
Nov 30, 2009 |
4.8 / 5 (49) |
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Super Earths are named for their size, but these planets - which range from about 2 to 10 Earth masses - could be superior to the Earth when it comes to sustaining life. They could also provide an answer to ...
Paleontologists find extinction rates higher in open-ocean settings during mass extinctions
Space & Earth / Earth Sciences
Nov 19, 2009 |
5 / 5 (1) |
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Arnie Miller, University of Cincinnati professor of paleontology in the McMicken College of Arts & Sciences, and co-author Michael Foote of the University of Chicago publish their research in the Nov. 20 issue ...
Mislabelling drives skate to brink of extinction
Nov 18, 2009 |
4.7 / 5 (6) |
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A species of common skate is to become the first marine fish species to be driven to extinction by commercial fishing, due to an error of species classification 80 years ago, reveals research published today ...
Killer fungus threatening amphibians
Nov 23, 2009 |
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Amphibians like frogs and toads have existed for 360 million years and survived when the dinosaurs didn't, but a new aquatic fungus is threatening to make many of them extinct, according to an article in the ...
Scientists find frog legs trade may facilitate spread of pathogens
Nov 19, 2009 |
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Most countries throughout the world participate in the $40-million-per-year culinary trade of frog legs in some way, with 75 percent of frog legs consumed in France, Belgium and the United States. Scientists ...
Sharks under threat as environmental change bites hard
Nov 17, 2009 |
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(PhysOrg.com) -- Their size and fearsome appearance have made them the stuff of nightmares, but new research just published suggests that sharks may not be as tough as they appear.
EU: bluefin tuna catches to be reduced
Nov 16, 2009 |
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(AP) -- The EU Commission says over 45 countries who catch tuna have agreed to cut catches of the threatened Atlantic bluefin tuna next year.
