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

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???

9. 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

10. 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)

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

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

13. USA

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

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

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

24. 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

25. 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

27. 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

28. 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

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

31. 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

33. 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

34. 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

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

36. 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

39. Climate change

43. 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

44. Dusky Seaside Sparrow

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

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

47. 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