Glossary of Ecology Unit 2 (3)

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a combination of the number of species and their relative abundance defines species diversity
total number of species (variety)
distribtuion of dominance (equality)
Alpha diversity
diversity of a particular community (local diversity)
Gamma diversity
diversity of all the communities within an area (regional diversity)
Beta diversity
species turnover between communities
Intermediate disturbance hypothesis
intermediate levels of disturbance promote higher diversity
Simpons's Index
C = 1 - sum[Pi]2
Inverted Simpson's Index
D = 1/ sum[Pi]2
Shannon-Wiener index
H = -sum[Pi ln(Pi)]
MacArthur-Wilson model
Number of species on islands balances regional process governing immigration (I) against local processes governing extinction (E).
Area effect
increased A -> increased population size -> decreased E
Habitat effect
increased A -> increased habitat diversity -> decreased E
Distance effect
increased D -> decreased I
Equilibrium theory of continental areas
equilibrium number of species in a large area in a mainland region, is determined by the balance between the speciation and extinction
Species-area curve
increased A =
increasing habitat diversity
increasing probability of including rare species
decreasing extinction rate

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