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15 Cards in this Set
- Front
- Back
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Biogeography
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the study of varioation in species composition and dicersity amoung geographic locations
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Richness
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number of different species in a given area
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Simpson index
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a measure of species diversity weighted by the relative abundance of each species. the higher the value the greater the diversity
D=1/ (Σpi²) |
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Evenness
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relative abundance of different species in a given area
low evenness= #s are very different high evenness= #s are about the same |
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How do you measure diversity?
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1. species richness
2. evenness 3. diversity indexes (Simpson's) |
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pi
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proportion of individuals of a given species to the total # of individuals in the community
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gamma diversity
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species diversity at the regional scale
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alpha diversity
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species diversity at the local scale
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beta diversity
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the CHANGE in species #s and composition (turnover species) as one moves from one community to another
calculated with Sorrensen's index |
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Sorrensen's index
β |
# species in common
_____________________________ average # species in each community β=1=exactly the same=low diversity β=0=high diversity |
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Equilibrium theory of island biogeograpy
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(Robert MacArthur and E.O. Wilson)
"the # of species on an island results from a dynamic balance between immigration rates and extinction rates" |
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Distance Effect
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the closer the island is to the mainland the higher the immigration rates
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Extinction rate
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# species lost on a specific island
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Size of Island effect
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the smaller the island the higher the extinction rates
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intersection of the extinction curve and immigration curve determines...
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what is the number of species on the island
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