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Biodiversity

Biodiversity. Ch10, Section 2: Biodiversity at Risk Standards: SEV1a, 1d, 1e. What is the difference between threatened, endangered, & extinct?. Threatened- species is declining so much it is likely to become endangered if not protected.

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Biodiversity

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  1. Biodiversity Ch10, Section 2: Biodiversity at Risk Standards: SEV1a, 1d, 1e

  2. What is the difference between threatened, endangered, & extinct? • Threatened- species is declining so much it is likely to become endangered if not protected. • Endangered- species that is likely to become extinct if not protected. • Extinct- last members of a species die. • Local extinction- species is extinct in local area/region • Global extinction- species is extinct on entire planet

  3. What are natural causes of extinction? • There have been 5 major natural mass extinctions since the beginning of geologic time. • These are caused by • Asteroids • Major volcanic eruptions • Both caused drastic changes in climate. • Many species could not adapt quickly enough so they died.

  4. What is the “6th extinction”? • “6th extinction” is not caused by natural events- caused by humans. • Rate of extinction has increased by multiple of 50 since 1800.

  5. What types of species are prone to extinction? • Generalist species • Large populations & adapt easily • NOT likely to become extinct • Ex: cockroach, rat, racoon • Specialist species • Small populations & can’t adapt easily b/c they have specialized needs for food or habitat • Includes many species that migrate-whooping crane • May be exploited by humans • Ex: giant panda, salamanders

  6. How do humans cause extinctions? • Remember H-I-P-P-O • These are the 5 ways humans cause extinctions. • H- Habitat Destruction • I- Invasive exotic species • P- Pollution • P- Poaching • O- Overharvesting

  7. H- Habitat Destruction/Fragmentation • Humans use land to • Build homes • Build roads, canals • For agriculture • Using the land, we destroy & fragment animal habitats • Causes 75% of all extinctions • Ex: Florida Panther- range consisted of entire southeast, now restricted to southernmost tip of Florida thanks to habitat fragmentation. Need lots of territory to live & hunt

  8. I- Invasive exotic species • Endemic- native to an area and usually limited in number • Exotic species- not native to a particular area. • Invasive- cause damage in a particular area. • Invasive exotics are more successful than endemics b/c: • Do not have natural predators • Outcompete endemic species for space/food • Ex: kudzu, fire ants, zebra mussels, snakehead fish

  9. Invasive exotics introduced intentionally…? • Invasive exotic mongoose was brought to Hawaii to get rid of another invasive species- rats. • Rats are active at night. • Mongoose was active during the day. • Instead of eating rats, mongoose ate native birds & their eggs. • Epic Fail.

  10. P- Pollution • Types of pollutants • Cleaning agents • Drugs & other chemicals • Burning fossil fuel- makes water acidic for fish & amphibians • Pesticides • Ex: DDT- used in 1950’s • Caused egg shells of bald eagles to become too thin. • Mother birds sat on eggs to incubate and they would break. • Main reason bald eagles were on endangered species list. • DDT banned in 1970s and now bald eagle populations have recovered.

  11. P- Poaching • Poaching- illegal hunting of an organism • Laws are established in many countries to prevent illegal hunting. • In developing countries these organisms may be a source of food, medicine or income. • Should they stop killing “pretty animals” or feed their families with them? • Ex: all large cats (skin, teeth gallbladders), elephants (ivory tusks), rhinos (horns for “medicine”)

  12. O- Overharvesting • In the past, catching fish or whales was done with small boats, harpoons, rods/reels • Now technology enables us to locate & harvest them in large quantities. • Ex: most commercial fish are overharvested

  13. What regions have the most critical levels of biodiversity? • Tropical rainforest • Cover less than 7% of land but have 50% of world’s species • Still many unknown species that may benefit man (medicine) • Cora reefs & coastal ecosystems • Invertebrate “nurseries”- many mollusks & crustaceans lay eggs here & babies grow up here • Used for food, ecotourism • Protect mainland from waves, storms • Not well protected by laws- overfishing & pollution • Islands • Have distinct & limited number of species • Very vulnerable to disturbances by people

  14. What is a biodiversity hotspot? • Biodiversity hotspots • The most threatened areas of high species diversity. • Have high number of endemic species and threatened by human activities • Most have lost 70% of their original habitat thanks to human encroachment. • Ex: Madagascar (see map)

  15. Are any biodiversity hotspots in U.S.? • Yes! • Some of our hotspots: • FL Everglades • Midwestern Prairies • CA coastal region • Pacific northwest rainforest • Hawaii • Organisms threatened by • Land use for agriculture & housing • Dam construction • Overuse of water • Mining

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