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16 Cards in this Set
- Front
- Back
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About what percentage of species known to science are extinct.
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99%
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About what percentage of the world's biodiversity may be lost by the middle of the century?
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20%
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Scientists estimate that no more than _____ percent of the world's eukaryotic organisms have been discovered.
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15%
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What are megafauna?
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Animals weighing more than 100 pounds.
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Where have the majority of historic extinctions occurred?
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Islands.
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What does it mean for a species to be endemic?
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It is found naturally in one area and no place else.
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What are hotspots?
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Areas of high endemism. They seem to be disappearing at a rapid rate.
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What are the three principle values of biodiversity?
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1. Direct Economic Value (use plants for stuff), 2. Indirect Economic Value (plants in environment prevent bad stuff), 3. Ethical and Aesthetic Value (living things are pretty).
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What was originally the major cause of extinction? What is it now? What ranks second?
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Overexploitation. Habitat loss. Introduced species.
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Why have declining amphibian populations been a concern for scientists?
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1. They have gone extinct even in protected habitats, 2. Amphibians are good gauges of the state of the environment, and 3. No single cause is apparent.
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What are the four types of habitat loss caused by humans?
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1. Destruction, 2. Pollution, 3. Disruption, and 4. Habitat Fragmentation.
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What causes populations' chances of survival to degrade after habitat fragmentation?
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Edge effects like changes in microclimate and increased predation.
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What two things cause an "extinction vortex"?
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Demographic Factors and Lack of Genetic Variablility.
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How can endangered environments and species be preserved?
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Habitat restoration and captive breeding.
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What are the types of habitat restoration?
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Pristine (total reconstruction), Removal of Introduced Species, and Cleanup/Rehabilitation.
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What are megareserves? How many have been established in Costa Rica?
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Large areas of land containing a core of one or more undisturbed habitats. Eight.
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