chapt59 - Conservation Biology Chapter 59 1 Factors...

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1 Conservation Biology Chapter 59
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2 Factors Responsible Causes of extinction: direct or indirect Overexploitation Habitat loss Introduced species Disruption of ecosystem interactions Pollution Loss of genetic variation Catastrophic disturbances
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3 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
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4 Factors Responsible
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5 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 1/3 rd are threatened with extinction
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6 Factors Responsible
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7 Factors Responsible Why worry about amphibian declines ? 1. Many species have declined in pristine, well-protected habitats 2. Particularly sensitive to the state of the environment because of their moist skin Chemicals pass into their body Larval habitats are aquatic
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8 Factors Responsible 3. No single cause for amphibian decline is apparent Different species are afflicted by different problems Global environment is deteriorating in many different ways
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9 Factors Responsible Habitat loss devastates species richness Natural habitats may be adversely affected by humans 1. Destruction 2. Pollution 3. Disruption 4. Habitat fragmentation
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10 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
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11 Rain forest covering the eastern coast of Madagascar: 90% habitat loss many extinctions 16 of 31 primate species threatened or extinct Factors Responsible
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12 Factors Responsible Extinction and Island Area
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13 Factors Responsible Pollution Species can no longer survive Aquatic environments particularly
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This note was uploaded on 09/16/2008 for the course BIOL 1722 taught by Professor Jagdeeswaran during the Spring '08 term at North Texas.

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chapt59 - Conservation Biology Chapter 59 1 Factors...

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