Ecology Unit 2 (3)
Terms
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- Diversity
- a combination of the number of species and their relative abundance defines species diversity
- Richness
- total number of species (variety)
- Evenness
- 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
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increased A =
increasing habitat diversity
increasing probability of including rare species
decreasing extinction rate