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Today finish biodiversity (Chapter 23) start conservation biology (Chapter 25) Wednesday

Today finish biodiversity (Chapter 23) start conservation biology (Chapter 25) Wednesday conservation biology Friday quiz! conservation biology Monday historical biogeography (Chapter 24) Wednesday ecosystem management (outside reading).

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Today finish biodiversity (Chapter 23) start conservation biology (Chapter 25) Wednesday

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  1. Today • finish biodiversity (Chapter 23) • start conservation biology (Chapter 25) Wednesday • conservation biology Friday • quiz! • conservation biology Monday • historical biogeography (Chapter 24) Wednesday • ecosystem management (outside reading)

  2. Conservation Biology - a mission-oriented science that focuses on protecting and restoring biodiversity Biodiversity • All forms of life • All levels of organization (subpopulation to biosphere) • All interactions among forms of life and the environment

  3. Where is the biodiversity? • Endemic species – restricted to a small region • isolated areas (islands, mountain ranges) • product of unique habitat, climate features

  4. Biodiversity hotspots - areas with a high concentration of endemic species, experiencing rapid habitat loss

  5. Hotspots: • 1.4% of the land area • 44% of vascular plant species • 35% of terrestrial vertebrate species • But… • 20% of the human population, which is… • growing at 1.8% per year (vs. 1.3% worldwide) • each hotspot has already lost 70% of its vegetation

  6. Current Status of Biodiversity • 1.4 million described species, possibly 10 million in total • Background extinction rate – rate of species loss in the absence of human activities • fossil record: species survive 1-10 million years • one year: one species has a 1 in 1-10 million chance of going extinct • total: 1 extinction per year

  7. Mass extinction – loss of large number of species • usually due to catastrophic volcano or meteor impact • very rare (5 times in 3 billion years) • Current rate of extinction???

  8. Some estimates for current rate: • 1 species per hour • 1 million species total, so far • 10% of all species so far • 8.8% of all species • 27,000 species per year • 20% of neotropical plant species • 100 to 10,000 times the background rate

  9. Numbers of threatened/endagered species: • 5,188 vertebrates (9%) • 1,992 invertebrates (0.17%) • 8,321 plants (2.89%) • 2 lichens (0.02%) • Since 1600, ~1000 species have gone extinct (probably many more)

  10. Why do species go extinct? 2 separate processes: • Something causes a large population to decline. • Small populations go extinct.

  11. Causes of species declines • Habitat destruction and fragmentation • Introduced species • Exploitation and overharvesting • Pollution • Climate change

  12. USA

  13. Habitat destruction and fragmentation Fragmentation – disruption of extensive habitats into small, isolated patches

  14. Relaxation – loss of species from isolated habitats over time S Area

  15. Edge effects – negative impacts adjacent to habitat boundaries • Forest edges: • more sunlight • drying • high winds • tree mortality • invasive species • more predators

  16. Edge area Core area • Core area – part of a patch not impacted by edge effects • Patch size is not always the best predictor of patch quality

  17. Introduced species • Humans are constantly moving species between continents, islands • deliberate or accidental • Most serious impacts on islands • low species diversity • few native predators • animals lack anti-predator defenses, resistance to diseases

  18. Characteristics of invasive species • pioneer species • high dispersal rates • found in disturbed habitats, but… • some can invade undisturbed communities • Why are invasives successful? • no diseases, herbivores, parasites, predators • better competitors than native species

  19. Introduced diseases – exploit lack of evolved resistance • Dutch elm disease – American elm • Chestnut blight – American chestnut • avian malaria – Hawaiian birds • Rinderpest – African ungulates • chytrid fungus – amphibians

  20. Net result of invasive species • homogenize ecological communities around the world • drive native, endemic species extinct

  21. Exploitation and overharvest • Direct exploitation for food • overfishing • “bycatch” in fisheries – killing non-target species (birds, marine mammals) • “bush meat” – harvest of wild animals for food • can be sustainable, but often not • threatens many large mammals, primates

  22. Global trade in wildlife • birds, orchids, cactus, primates • captured for gardens, pets, zoos, etc. • Many species driven extinct before hunting/harvest regulations were in place • passenger pigeon, island tortoises, marine mammals

  23. Exam • Definitions, compare-contrast – 5 points each (20 points per page) • 5 questions – 12 points per question • bonuses – 3 points each • dropped the question with the lowest score • Average grade = 86

  24. Causes of species declines • Habitat destruction and fragmentation • Introduced species • Exploitation and overharvesting • Pollution • Climate change

  25. Pollution • Most important for aquatic systems • chemical pollutants • acid precipitation • Bioaccumulation – process by which toxin concentrations increase in living tissues • concentrations increase through the food chain

  26. Climate change

  27. Why do small populations go extinct? • Demographic stochasticity – chance events that occur at small populations size • failure to breed or survive • failure to find a mate • skewed sex ratio

  28. Dusky Seaside Sparrow

  29. Environmental effects – unpredictable events that reduce survival or reproduction • droughts, floods, fires, storms • Genetic effects at small population size • inbreeding • genetic drift • random mutations

  30. Extinction vortex – combination of genetic, environmental and demographic factors that drive a small population to extinction

  31. Heath hen • 1700 – throughout the northeast coast • 1907 – 50 left on Martha’s Vineyard • 1915 – 2000 birds • 1916 – fire • 1917 – goshawk invasion • 1920’s – poultry disease • 1927 – 13 birds, mostly males • March 11, 1932 – last known sighting

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