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WELCOME PRESENTED BY SARANIYA PRADEEP NATURAL SCIENCE ROLL.NO.84

Species extinction- animals

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Page 1: Species extinction- animals

WELCOME

PRESENTED BY SARANIYA PRADEEP

NATURAL SCIENCEROLL.NO.84

Page 2: Species extinction- animals

This power point presentation focuses on “species extinction”

described in the Biology text book of 8th standard, in chapter 3-BEAUTY OF NATURE

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SPECIES EXTINCTION

ANIMALS

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• Extinction-first described in 1750s.• The possibility of extinction widely accepted

before the 1800s.• Georges Cuvier established extinction as a fact

in 1796.

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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.

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• 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.

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• 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.)

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EXTINCTION-MAJOR CAUSES

• Deforestation/habitat loss• Hunting/poaching• Over exploitation• Introduction of exotic species• Global warming• Predation,diseases,competition,pollution

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

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• HUNTING is another major cause of extinction

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• The DODO Bird became extinct due to hunting

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• 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.

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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.

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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.

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Major Extinction Events in the history of the planet

• 5 largest mass extinctions occurred.• The late Ordovician period.• The late Devonian period.• At the end of the Permean period.• The late Triassic period.• At the Cretaceous period.

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THANK YOU