Conservation Biology Chapter 59

1. Conservation BiologyChapter 59

2. Biodiversity Crisis • Extinction is a fact of life: all species become extinct eventually • More than 99% of species known to science are now extinct • Current accelerating loss of habitat • 20% of present day species will be extinct by the middle of this century • 2000 of the world’s 8600 species of birds could go extinct

3. Biodiversity Crisis • Members of Homo sapiens wreaked havoc even in prehistoric times • Mammoths and mastodons, giant sloths, saber-toothed tigers • 74% - 86% of mega fauna thought to have been caused by human hunting

4. Biodiversity Crisis • 40,000 years ago Australia had mega sized marsupials • All disappeared at about the same time humans arrived • Madagascar human caused extinctions • 15 species of lemurs • Pigmy hippopotamus • Flightless elephant bird (3m tall), 13 species of moas, and more

5. Biodiversity Crisis Why have African mega fauna survived ? • Perhaps because animals coevolved with humans there • Animals evolved counteradaptations to human predation

6. Biodiversity Crisis • The majority of recent extinctions have occurred in the past 150 years • Increased rate of extinction is worsening • Birds recognized as critically endangered increased from 8% in 1996 to 2000 • Half of Earth’s plant species may be threatened • 2/3rds of vertebrate species could perish by the end of this century

7. Biodiversity Crisis • Majority of extinctions have occurred on islands • 85 species of mammals; 60% lived on islands • Why are islands so vulnerable ? • Evolved in the absence of predators • Humans introduced competitors, diseases • Island populations are usually small which increases their risk for extinction

8. Biodiversity Crisis • Current mass extinctions are notable because • It is the only such event triggered by a single species (Homo sapien) • A few million years is a long time to wait for recovery • It is not clear that biodiversity will rebound this time • Humans are utilizing resources that new species would need to evolve

9. Biodiversity Crisis • Endemic species: species found naturally in only one geographic area and no place else • Occupy restricted ranges • Example: Komodo dragon lives only in a few islands • Example: Mauna Kea Silversword only lives in a single volcano crater on the island of Hawaii

10. Biodiversity Crisis Silversword

11. Biodiversity Crisis (Cont.) Some species under imminent extinction threat

12. Biodiversity Crisis Hotspots: areas where species have high endemism and are disappearing at a rapid rate. Red areas are hotspots.

13. Biodiversity Crisis 25 hotspots have been identified Contain nearly half of all terrestrial species in the world

14. Biodiversity Crisis • Human population growth in hotspots • By protecting 1.4% of the world’s land surface • 44% of the worlds vascular plants • 35% of its terrestrial vertebrates can be preserved • In 1995, 20% of the human population were located in hotspots • Growth rate exceeds the average in 19 hotspots

15. Biodiversity Crisis

16. Biodiversity Crisis Why are species going extinct in hotspots ? • High rates of habitat destruction • Land cleared for agriculture, housing, economic development • More than 70% of the original area of each hotspot has already disappeared • Only 15% or less of original habitat remains in 14 hotspots • 90% Madagascar forest lost • 95% Brazilian forest lost

17. Value of Biodiversity • Why care about loss of biodiversity ? • Direct economic value of products we obtain from species: food and drugs • Indirect economic value of benefits produced by species without our consuming them • Ethical and aesthetic values

18. Value of Biodiversity • Direct economic value includes resources for our survival • Food crop genetic variation • 40% of prescription and nonprescription drugs have active ingredients extracted from plants • Aspirin • Cancer fighting drugs

19. Value of Biodiversity • Rosy Periwinkle: vinvlastine and vincristine effectively treat common forms of childhood leukemia • Increase chances of survival from 20% to over 95%

20. Value of Biodiversity Cancer-fighting drugs like taxol, have been developed from the bark of the Pacific yew

21. Value of Biodiversity • Indirect economic value is derived from ecosystem services • Maintain chemical quality of natural water, buffer against storms and droughts • Prevent loss of minerals and nutrients • Moderate local and regional climate • Absorb pollution • Promote breakdown of organic wastes and cycling of minerals

22. Value of Biodiversity Mangroves in Thailand are more Valuable than Shrimp farms

23. Value of Biodiversity Tropical rainforests provide more economic benefits if they are left standing than if they are destroyed and the land used for other purposes

24. Value of Biodiversity Case Study: New York City watershed • 90% of 9 million people’s water comes from the Catskill Mountains and Delaware River • Dilemma: Protect functioning ecosystem or construct filtration plants • To build plants cost $6 billon • Operating cost $300 million/year • Spend $1 billion over 10 years to preserve the ecosystem

25. Value of Biodiversity New York City’s water source

26. Value of Biodiversity • Economic trade-offs • Ecosystem was beneficial when the United States was being settled • Habitat destruction today may be economically desirable • How many services will it provide • What are the negative effects • Increased flooding and pollution • Decreased rainfall • Vulnerability to hurricanes

27. Value of Biodiversity • Consequences of removing a species could mean we are gambling with the future of an ecosystem we depend on • Problems of valuing ecosystems • Do not have a good estimate of the monetary value of services provided by ecosystems • People who gain the benefits of environmental degradation are often not the same people who pay the costs

28. Value of Biodiversity • Ethical and aesthetic values are based on our conscience • Every species has a value of its own • Humans should act as guardians or stewards for the diversity of life around us • How do we place a value on beauty ? • What if it no longer existed ?

29. Value of Biodiversity

30. Factors Responsible • Causes of extinction: direct or indirect • Overexploitation • Habitat loss • Introduced species • Disruption of ecosystem interactions • Pollution • Loss of genetic variation • Catastrophic disturbances

31. Factors Responsible • Case Study: Amphibians on the decline • 1963, Jay Savage Costa Rica • Many breeding toads, bright orange • Bufo periglenes • 1989, only a single male was observed • Today, no toads • They have gone extinct

32. Factors Responsible

33. Factors Responsible • Frogs in trouble • Frog populations that had once been abundant were now decreasing or entirely gone • 2005: 43% of amphibian species experienced decreases in population size • 1/3rd are threatened with extinction

34. Factors Responsible

35. Factors Responsible (Cont.)

36. Factors Responsible (Cont.)

37. Factors Responsible Why worry about amphibian declines ? • Many species have declined in pristine, well-protected habitats • Particularly sensitive to the state of the environment because of their moist skin • Chemicals pass into their body • Larval habitats are aquatic

38. Factors Responsible • No single cause for amphibian decline is apparent • Different species are afflicted by different problems • Global environment is deteriorating in many different ways

39. Factors Responsible • Habitat loss devastates species richness • Natural habitats may be adversely affected by humans • Destruction • Pollution • Disruption • Habitat fragmentation

40. Factors Responsible • Destruction of habitat • Clear-cut harvesting of timber • Burning of tropical forests • Urban and industrial development • 10 fold increase in habitat area leads to ~ doubling in the number of species • Area reduced by 90% then half of all species will be lost

41. Factors Responsible Rain forest covering the eastern coast of Madagascar: • 90% habitat loss • many extinctions • 16 of 31 primate species threatened or extinct

42. Factors Responsible Extinction and Island Area

43. Factors Responsible • Pollution • Species can no longer survive • Aquatic environments particularly vulnerable • Many lakes “sterilized” by acid rain • Disruption • Visitors to bat cave: four visits per month caused 86% - 95% declines in population size

44. Factors Responsible • Habitat fragmentation: dividing the habitat up into small, unconnected areas • Low population numbers • Smaller populations in each fragment • Edge effects: changes in microclimate along the edge of a habitat

45. Factors Responsible • Edge effects • Trees exposed to more sunlight • Hotter and drier conditions • Less biomass growth • Opportunities for parasite and predator species • Habitat fragmentation is blamed for local extinctions in a wide range of species

46. Factors Responsible • Fragmentation of Wisconsin woodland habitat • Cover less than 1% of original area

47. Factors Responsible • Landowners in Manaus, Brazil preserved patches of rain forest of different sizes to examine the effect of patch size on species extinction • Extinction rate was negatively related to patch size • Even the largest patches (100 hectares) lost half of their bird species in less than 15 years

48. Factors Responsible Manaus, Brazil

49. Factors Responsible Case Study: songbird declines • Year round residents prosper (robins) • Migrant songbirds have declined • Nest in northern forests in summer but spend winter in South or Central America or the Caribbean Islands • Rock Creek Park in Washington, DC lost 90% in the past 20 years

50. Factors Responsible • Nation wide, American redstarts declined about 50% in 10 years • Only about has as many birds fly over the Gulf of Mexico each spring as in the 1960’s • Culprit: • habitat fragmentation and loss • Availability of winter habitat declined