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lecture14 - Species Diversity 2 July 1 Community Community...

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Unformatted text preview: Species Diversity 2 July 1 Community Community a set of species living in a particular place Species richness number of species Species diversity a measure of number and evenness of species 0.4 40 3 0.3 30 2 0.3 30 1 p i No. of ind. Species 0.98 98 3 0.01 1 2 0.01 1 1 p i No. of ind. Species Simpsons index (D) probability of picking two organisms at random that are different species Community A Community B D = 1- (p i ) 2 Community A: D=0.66 Community B: D=0.04 Why are there more species in the tropics Why are there more species in the tropics than in other areas on earth? than in other areas on earth? Latitudinal Species Diversity Gradients Latitudinal Species Diversity Gradients Examples: Species Diversity 2 July 2 1. Time Hypothesis tropical communities have had more time for speciation than temperate or polar communities Glaciation events Time Time N o . o f s p e c i e s N o . o f s p e c i e s Tropical Temperate 2. Climate Hypothesis more species can adapt to favorable climate in the tropics than harsh climate in other areas. 3. Area Hypothesis tropical zones contain more area on the globe than temperate areas Why are there more species in the tropics Why are there more species in the tropics than in other areas on earth? than in other areas on earth? F r e q u e n c y F r e q u e n c y Resource Resource 4. Competition Hypothesis species are more specialized in the tropics, allowing more species to coexist Tropical Temperate 5. Predation Hypothesis predation is stronger in the tropics...
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This note was uploaded on 01/06/2010 for the course EVE 101 taught by Professor Strong,d during the Spring '08 term at UC Davis.

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lecture14 - Species Diversity 2 July 1 Community Community...

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