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Extinctions

Extinctions. Loss of Biodiversity. EXTINCTION - the disappearance of a species Extinctions have been occurring constantly at a low 'background rate', usually matched by the rate at which new species appear - resulting in an overall increase in biodiversity

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Extinctions

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  1. Extinctions

  2. Loss of Biodiversity • EXTINCTION - the disappearance of a species • Extinctions have been occurring constantly at a low 'background rate', usually matched by the rate at which new species appear - resulting in an overall increase in biodiversity • A world without extinction would be really crowded!!

  3. Estimates of Organisms • Fossil record from Precambrian period estimate total number of species on Earth at 500 million • Current numbers of names species is 1.5 – 2 million • Current estimates of total species ranges between 3 – 30 million

  4. Mass Extinctions • There have been several major extinctions since the beginning of life 3.5 billion years ago

  5. End of Ordovician (440 mya) • 2nd most devestating in Earth’s history • Effecting marine species • Probably due to glaciation Source:http://www.palaeos.com/Paleozoic/Ordovician/Ordovician.htm

  6. Late Devonian (365 mya) • Effecting marine and terrestrial species • Possibly due to global cooling since many warm water species were lost • Occurred over 500,000 -15 million years Source: http://www.palaeos.com/Paleozoic/Devonian/Devonian.2.htm

  7. Late Permian (225 mya) • Largest extinction • estimated that as many as 95% of all marine species were lost • Possible causes • continents merging to form Pangea • global warming caused by volcanic eruptions • glaciation Source: http://www.palaeos.org/Permian

  8. Late Triassic (200 mya) • ¼ of terrestrial families • Possible causes • Climate change • Increased rainfall • Loss of biodiversity allowed dinosaurs to exploit abandoned niches Source:http://images.google.com/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Iguanodon1.jpg/250px-Iguanodon1.jpg&imgrefurl=http://en.wikipedia.org/wiki/The_Crystal_Palace_Dinosaurs&h=186&w=250&sz=9&hl=en&start=29&tbnid=68NenapFjPWS7M:&tbnh=83&tbnw=111&prev=/images%3Fq%3DLabyrinthodon%26start%3D20%26gbv%3D2%26ndsp%3D20%26hl%3Den%26sa%3DN

  9. Cretaceous-Tertiary (65 mya) • Effecting ½ of all marine species • Terrestrial plants, dinosaurs, and reptiles became extinct. • Gave rise to mammals • Possible causes: • Impact hypothesis – comet collided with the earth Source: http://www.worldbook.com/wb/Students?content_spotlight/dinosaurs/world_mesozoic

  10. Pleistocene (11, 000 ya) • Ice age period • Loss of 75% of large genus (mammals) • Possible causes • Hunting • Climate change • Disease Source: http://www.msnbc.msn.com/id/12721432/

  11. Recent Extinction Rates • 11,000 – 400 ya • 1% of species per decade • 400 – 100 ya • 1% of birds and mammals • Approximately 1% per decade • Presently • 1% per day

  12. Recent Extinction Rates continued • The ratio of 1600:present = 1:10 • Much faster than natural • By the year 2010 over 500,000 species of plants and animals will have become extinct since the Pleistocene

  13. Past causes of extinction • Climate change • Volcanic events • Magnetic reversal of the poles • Sea level changes • Collision of Meteorites • Glaciations • Plate tectonics • Competition / predation

  14. Present causes of extinction/loss of biodiversity - • Mostly human impact • HIPPO • Habitat destruction • Introduced species • Pollution • Population • Over consumption

  15. Habitat destruction • Degradation • e.g. stream siltation caused by deforestation • Fragmentation • e.g.highways through national parks • Loss • e.g. new strip mall on Hanes Mall Blvd

  16. Introduced species • Non-native species • e.g. green crab, zebra mussel, ctenophore in Mediterranean Sea • Genetically modified species

  17. Pollution • Air • Water • Land • Major sources: • Fossil fuels • Domestic waste • Industrial waste • Manufacturing processes • Agriculture

  18. Population • With the global population increasing at a rate of 3 people per second there is: • Increasing use of resources • Increasing habitat destruction • Increasing waste production

  19. Over consumption • Hunting, collecting, harvesting • e.g. Atlantic cod for food • e.g. sea otter for fur • Wildlife trade e.g. bear gallbladders as aphrodisiacs • Indirectly through over consumption of resources e.g. water, land

  20. Problems • Don’t know total number of species on planet • Difficult to quantify the relationship between man’s impact and species loss • Difficult to quantify the relationship between mans impact and habitat loss

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