Extinction Of Bio-Diversity
Extinction Of Bio-Diversity
Extinction: In biology and ecology, extinction refers to the permanent end of an organism or of a group of organisms, normally a species. It is generally considered as the death of the last individual of the group (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.
During 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. Most extinction occurs naturally, without human intervention; it is estimated that 99.9% of all species that have ever existed are now extinct.
Mass extinctions are relatively rare events; however, isolated extinctions are quite common. Only recently have extinctions been recorded and scientists have become alarmed at the high rates of recent extinctions. Most species that become extinct are never scientifically documented. Some scientists estimate that up to half of presently existing species may become extinct by 2100.
In 2006, many species were formally classified as rare, endangered, or threatened. Moreover, scientists have estimated that millions more species are at risk, which has not been formally recognised. About 40 percent of the 40,177 species, assessed using the IUCN Red List criteria, are now listed as threatened with extinction-a total of 16,119.
Mass extinction is defined as the __________
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| Right Option : C | |||
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Which of the following factors help in the stability of an ecosystem ? | |||
| Right Option : C | |||
| View Explanation | |||
Which of the following are human benefits of biodiversity ? | |||
| Right Option : D | |||
| View Explanation | |||
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