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Species extinction- animals


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Species extinction- animals

  2. 2. This power point presentation focuses on “species extinction” described in the Biology text book of 8th standard, in chapter 3-BEAUTY OF NATURE<br />
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  5. 5. 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 />
  6. 6. 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 />
  7. 7. 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 />
  8. 8. 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 />
  9. 9. EXTINCTION-MAJOR CAUSES<br />Deforestation/habitat loss<br />Hunting/poaching<br />Over exploitation<br />Introduction of exotic species<br />Global warming<br />Predation,diseases,competition,pollution<br />
  10. 10. DEFORESTATION leads to loss of habitat for several animal species.<br />
  11. 11. H<br />HUNTING is another major cause of extinction<br />
  12. 12. t<br />The DODO Bird became extinct due to hunting<br />
  13. 13. 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 />
  14. 14. <ul><li>Exotic species introduction is also a reason for extinction.
  15. 15. Introduced exotic species put native species in danger by preying on them.
  16. 16. They alter the natural habitat & cause a greater competition for food, since they are intruders.
  17. 17. 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 />
  18. 18. 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 />
  19. 19. THANK YOU<br />