| Term | Definition |
|---|
| Biodiversity | the number, variety, and variability of living organisms. Often simply defined as the number of different species in a given geographic area. |
| Continental taxa | species that have evolved on continents |
| Equilibrium theories of biodiversity | theories which assume that modern biodiversity is in equilibrium with modern environmental conditions |
| Equilibrium theory of island biogeography | the theory that the biodiversity on islands is governed by rates of colonization and extinction, which in turn are controlled by island isolation and island size |
| Historical theories of biodiversity | theories that assume that modern biodiversity is not in equilibrium with modern environmental conditions because it reflects past events of the evolution and extinction |
| Insular taxa | species that have evolved on islands |
| Intermediate disturbance hypothesis | hypothesis that if an ecosystem remains stable and free of disruption by disturbance, the stable conditions will favor some species but will lead to the extinction of species for which the stable habitat is not favorable or which are prone to competitive exclusion by species that are favored by the undisturbed environment. Disturbances cause physical and biological changes and spatial heterogeneity in the system that can favor species that would not survive in a stable undisturbed system. On the other hand, if disturbance occurs too frequently and is too severe, it will lead to the extinction of disturbance sensitive species that have long generation times or occur in low numbers and are prone to change extinction |
| Nested pattern of insular communities | the general tendency for the biota on islands to contain a subset of the flora and fauna found on nearby larger islands or continents |
| Peninsula effect | the general observation that species richness on peninsulas also generally declines towards the tip of the peninsula |
| Species evenness | the degree to which the number of individual organisms are evenly divided between the different species of the community. An estimate is obtainable using the equation E = H'/In S |
| Species relaxation | the decline in species richness that occurs when a region, such as a landbridge island, is cutoff from a larger landmass or area of similar habitat. Also occurs when land clearance produces small reserves in place of once extensive areas of natural habitat |
| Species richness | the number of different species in a given area. In many large-scale biogeographical studies, biodiversity is synonymous. |
| Species turnover | changes in the species represented at different sites or between different time periods at the same site |
| Stability-time hypothesis | the hypothesis that long periods of environmental stability lead to high species richness |
| Target area effect | the observed positive relationship between island size and immigration rates due to the fact that larger islands provide a bigger target for dispersing organisms |
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