co50 - CHAPTER 50 CONSERVATION BIOLOGY Chapter Outline 50.1...

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CHAPTER 50 C ONSERVATION B IOLOGY Chapter Outline 50.1 Conservation Biology and Biodiversity A. Conservation Biology 1. Conservation biology is a new discipline studying aspects of biodiversity in order to conserve natural resources. 2. Conservation biology involves both scientific concepts and their application to practical problems. 3. It supports four principles. a. Biodiversity is desirable for both the biosphere and for humans. b. Extinctions due to human actions are undesirable. c. The complex interactions in ecosystems support biodiversity and are therefore desirable. d. Biodiversity from evolutionary change has value by itself regardless of any practical benefit. 4. Estimates vary but at least 10–20% of all species now living will most likely become extinct in 20–50 years. B. Biodiversity 1. Species biodiversity is the number of species of bacteria, plants, animals, etc. 2. Most estimates place the number of species living on earth as between 5 and 15 million species; most are yet to be found and described. 3. To add more meaning for applications, diversity also includes genetic diversity, community diversity, and landscape diversity. 4. Genetic diversity helps maintain reproductive vitality and assists adaptation. a. The 1846 potato blight in Ireland was due to too little genetic diversity. b. 1922 saw a similar Soviet wheat failure. c. Florida had an outbreak of citrus canker in 1984 made worse by limited genetic variation. d. Such limited genetic variation creates the risk of extinction in natural populations. 5. Community diversity refers to the variation in species composition in a community. a. Different communities have different species; therefore different communities add to species diversity. b. Attempts to save just one species are shortsighted when the community itself is threatened. c. Disrupting a community can threaten many species. 6. Landscape Diversity a. Landscape diversity incorporates a number of interacting ecosystems: plains, mountains, rivers, etc. b. Fragmented ecosystems may connect by habitat corridors, strips allowing organisms to move between patches. C. Distribution of Diversity 1. Biodiversity is not evenly distributed; saving some areas saves more species than saving others. 2. Biodiversity is highest in the tropics and declines toward the poles on land, in fresh water, and in the ocean. 3. Biodiversity hotspots contain unusually large concentrations of species; 20% of these species are in only 1/2% of the earth’s land area. 4. Madagascar, the Cape of South Africa, and the Great Barrier Reef of Australia are all biodiversity hotspots. 5. Biodiversity frontiers such as the rain forest canopies and the deep sea benthos have more species than formerly suspected.
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50.2 Value of Biodiversity A. To reverse the trend toward species extinction, all people must realize the value of biodiversity as a resource. B. Medicinal Value
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co50 - CHAPTER 50 CONSERVATION BIOLOGY Chapter Outline 50.1...

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