1) The document focuses on species extinction as described in an 8th standard Biology textbook. It discusses the major causes of species extinction such as deforestation, hunting, overexploitation, introduction of exotic species, and global warming. 2) Some examples of extinct species given are the Dodo bird which became extinct due to hunting and many Harlequin frog species in Central and South America that disappeared due to infectious diseases caused by climate change. 3) There have been 5 major extinction events in history including at the end of the Ordovician, Devonian, Permian, Triassic, and Cretaceous periods.

1. WELCOMEPRESENTED BY SARANIYA PRADEEP NATURAL SCIENCEROLL.NO.84

2. This power point presentation focuses on “species extinction” described in the Biology text book of 8th standard, in chapter 3-BEAUTY OF NATURE

3. SPECIES EXTINCTIONANIMALS

5. Extinction-first described in 1750s.The possibility of extinction widely accepted before the 1800s.Georges Cuvier established extinction as a fact in 1796.

6. Extinction, in ecology refers to the end of a specific group of taxa.A taxon is extinct when there is no reasonable doubt that the last individual has died.

7. The IUCN-world conservation union has categorized species into different categories.Extinct species is the first category in it.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.

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.)

9. EXTINCTION-MAJOR CAUSESDeforestation/habitat lossHunting/poachingOver exploitationIntroduction of exotic speciesGlobal warmingPredation,diseases,competition,pollution

10. DEFORESTATION leads to loss of habitat for several animal species.

11. HHUNTING is another major cause of extinction

12. tThe DODO Bird became extinct due to hunting

13. OVER EXPLOITATION is another reason for species extinction.Demands for items like tiger skin, tiger bones, rhinoceros horns etc.has led to over exploitation.Unrestricted whaling during the 20th century is another example for overexploitation.

14. Exotic species introduction is also a reason for extinction.

15. Introduced exotic species put native species in danger by preying on them.

16. They alter the natural habitat & cause a greater competition for food, since they are intruders.

17. Zebra mussel is an example for exotic species.Globalwarming is another reason for species extinction. This may cause widespread Amphibian extinctions by triggering lethal epidemics.Eg:Many Harlequin frog species across Central & South America have disappeared due to deadly infectious diseases spurred by changing water & air temperatures.