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Chapter 55. Conservation Biology & Restoration Ecology. Overview: The Biodiversity Crisis. Conservation biology integrates these fields: Ecology Evolutionary biology Physiology Molecular biology Genetics Behavioral ecology.

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Chapter 55


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    1. Chapter 55 Conservation Biology & Restoration Ecology

    2. Overview: The Biodiversity Crisis • Conservation biology integrates these fields: • Ecology • Evolutionary biology • Physiology • Molecular biology • Genetics • Behavioral ecology

    3. Restoration ecology applies ecological principles to return degraded ecosystems to cond’s as similar as possible to their natural state

    4. Tropical forests containing some of the greatest concentrations of spp are being destroyed at an alarming rate • Throughout the biosphere, human activities are altering ecosystem processes on which we & other spp depend

    5. Concept 55.1: Human activities threaten Earth’s biodiversity • Rates of spp extinction are difficult to determine under natural conditions • The high rate of spp extinction is largely a result of ecosystem degradation by humans • Humans are threatening Earth’s biodiversity

    6. The 3 Levels of Biodiversity • Biodiversity- 3 main parts: • Genetic diversity • spp diversity • Ecosystem diversity

    7. LE 55-2 Genetic diversity in a vole pop spp diversity in a coastal redwood ecosystem Community & ecosystem diversity across the landscape of an entire region

    8. Genetic Diversity • Genetic diversity- genetic variation w/in a pop & b/w pop's

    9. spp Diversity • spp diversity- variety of spp in an ecosystem or the biosphere • endangered spp- danger of becoming extinct through its range • threatened spp- likely to become endangered in the future

    10. Conservation biologists are concerned about spp loss because of alarming statistics regarding extinction & biodiversity • Researchers estimate that at current rates of extinction more than ½ of current plant & animal spp will disappear in this century • Harvard biologist E. O. Wilson has identified the Hundred Heartbeat Club: spp w/ fewer than 100 indiv's

    11. LE 55-3 Philippine eagle Chinese river dolphin Javan rhinoceros

    12. Ecosystem Diversity • Human activity is reducing ecosystem diversity, the variety of ecosystems in the biosphere

    13. Biodiversity & Human Welfare • Human biophilia allows us to recognize the value of biodiversity for its own sake • spp diversity brings humans practical benefits

    14. Benefits of spp & Genetic Diversity • Many pharmaceuticals contain substances originally derived from plants • For example, the rosy periwinkle contains alkaloids that inhibit cancer growth

    15. The loss of spp also means loss of genes & genetic diversity • The enormous genetic diversity of organisms has potential for great human benefit

    16. Ecosystem Services • Ecosystem services encompass all the processes through which natural ecosystems & their spp help sustain human life • Some examples of ecosystem services: • Purification of air & water • Detoxification & decomposition of wastes • Cycling of nutrients • Moderation of weather extremes

    17. Four Major Threats to Biodiversity • Most spp loss can be traced to four major threats: • Habitat destruction • Introduced spp • Overexploitation • Disruption of “interaction networks”

    18. Habitat Destruction • Human alteration of habitat is the greatest threat to biodiversity throughout the biosphere • Many natural landscapes have been broken up, fragmenting habitat into small patches • In almost all cases, habitat fragmentation & destruction lead to loss of biodiversity

    19. Introduced spp • Introduced spp are those that humans move from native locations to new geographic regions • Introduced spp that gain a foothold in a new habitat usually disrupt their adopted community

    20. Sometimes humans introduce spp by accident, as in case of the brown tree snake arriving in Guam as a cargo ship “stowaway”

    21. LE 55-6 Brown tree snake, intro- duced to Guam in cargo. Introduced kudzu thriving in South Carolina

    22. Humans have deliberately introduced some spp w/ good intentions but disastrous effects • An example is the introduction of kudzu in the southern United States

    23. Overexploitation • Overexploitation- human harvesting of wild plants or animals at rates exceeding the ability of pop's of those spp to rebound • For example, the fishing industry has greatly reduced pop's of some game fish, such as bluefin tuna

    24. Disruption of Interaction Networks • Extermination of keystone spp by humans can lead to major changes in community structure

    25. Concept 55.2: pop conservation focuses on pop size, genetic diversity, & critical habitat • Biologists focusing on conservation at the pop & spp levels follow 2 main approaches: • The small-population approach • The declining pop approach

    26. Small-Population Approach • The small-pop approach studies processes that can make small pop's become extinct

    27. The Extinction Vortex • A small pop is prone to positive-feedback loops that draw it down an extinction vortex

    28. LE 55-9 Small pop Genetic drift Inbreeding Lower reproduction Higher mortality Loss of genetic variability Reduction in indiv fitness & pop adaptability Smaller pop

    29. The key factor driving the extinction vortex is loss of the genetic variation necessary to enable evolutionary responses to environmental change

    30. Case Study: The Greater Prairie Chicken & the Extinction Vortex • pop's of the greater prairie chicken were fragmented by agriculture & later found to exhibit decreased fertility • To test the extinction vortex hypothesis, scientists imported genetic variation by transplanting birds from larger pop's • The declining pop rebounded, confirming it had been on its way down an extinction vortex

    31. LE 55-10 200 150 # of male birds 100 50 0 1980 1985 1970 1975 1990 1995 2000 Year pop dynamics 100 90 80 70 Eggs hatched (%) 60 50 40 30 1993–97 1970–74 1975–79 1980–84 1985–89 1990 Years Hatching rate

    32. Minimum Viable pop Size • Minimum viable pop (MVP) is the minimum pop size at which a spp can survive • The MVP factors into a pop viability analysis (PVA), which predicts a pop’s chances for survival over a particular time

    33. Effective pop Size • A meaningful estimate of MVP requires determining the effective pop size, which is based on the pop's breeding size

    34. Case Study: Analysis of Grizzly Bear pop's • One of the first pop viability analyses was conducted as part of a long-term study of grizzly bears in Yellowstone National Park

    35. This study showed that the grizzly bear pop has grown substantially in the past 20 years

    36. LE 55-12 150 Females w/ cubs Cubs 100 # of indiv's 50 0 1973 2000 1982 1991 Year

    37. Declining-Population Approach • The declining-population approach • Focuses on threatened & endangered pop's that show a downward trend, regardless of pop size • Emphasizes the environmental factors that caused a pop to decline

    38. Steps for Analysis & Intervention • The declining-population approach • Requires that declines in pop be evaluated on a case-by-case basis • Involves a step-by-step proactive conservation strategy

    39. Case Study: Decline of the Red-Cockaded Woodpecker • Red-cockaded woodpeckers had been forced into decline by habitat destruction

    40. LE 55-13 A red-cockaded woodpecker perches at the entrance to its nest site in a longleaf pine. Forest that cannot sustain red-cockaded woodpeckers has high, dense undergrowth that impacts the woodpeckers’ access to feeding grounds. Forest that can sustain red-cockaded woodpeckers has low undergrowth.

    41. In a study where breeding cavities were constructed, new breeding groups formed only in these sites • Based on this experiment, a combination of habitat maintenance & excavation of breeding cavities enabled this endangered spp to rebound

    42. Weighing Conflicting Demands • Conserving spp often requires resolving conflicts b/w habitat needs of endangered spp & human demands

    43. Concept 55.3: Landscape & regional conservation aim to sustain entire biotas • Conservation biology has attempted to sustain the biodiversity of entire communities, ecosystems, & landscapes • Ecosystem management is part of landscape ecology, which seeks to make biodiversity conservation part of land-use planning

    44. Landscape Structure & Biodiversity • The structure of a landscape can strongly influence biodiversity