Extinction-first described in 1750s.<br />The possibility of extinction widely accepted before the 1800s.<br />Georges Cuvier established extinction as a fact in 1796.<br />
Extinction, in ecology refers to the end of a specific group of taxa.<br />A taxon is extinct when there is no reasonable doubt that the last individual has died.<br />
The IUCN-world conservation union has categorized species into different categories.<br />Extinct species is the first category in it.<br />A Taxon is presumed extinct when exhaustive surveys in known & expected habitat ,at appropriate times (diurnal, seasonal or annual) throughout its historic range have failed to record an individual.<br />
A Taxon is extinct in the wild when it is known only to survive in cultivation, in captivity or as a naturalized population (or populations well outside the past range.)<br />
DEFORESTATION leads to loss of habitat for several animal species.<br />
H<br />HUNTING is another major cause of extinction<br />
t<br />The DODO Bird became extinct due to hunting<br />
OVER EXPLOITATION is another reason for species extinction.<br />Demands for items like tiger skin, tiger bones, rhinoceros horns etc.has led to over exploitation.<br />Unrestricted whaling during the 20th century is another example for overexploitation.<br />
<ul><li>Exotic species introduction is also a reason for extinction.
Introduced exotic species put native species in danger by preying on them.
They alter the natural habitat & cause a greater competition for food, since they are intruders.
Zebra mussel is an example for exotic species.</li></li></ul><li>Globalwarming is another reason for species extinction. <br />This may cause widespread Amphibian extinctions by triggering lethal epidemics.<br />Eg:Many Harlequin frog species across Central & South America have disappeared due to deadly infectious diseases spurred by changing water & air temperatures.<br />
Major Extinction Events in the history of the planet<br />5 largest mass extinctions occurred.<br />The late Ordovician period.<br />The late Devonian period.<br />At the end of the Permean period.<br />The late Triassic period.<br />At the Cretaceous period.<br />