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The observed species richness is affected not only by the number of individuals but also by the heterogeneity of the sample. If individuals are drawn from different environmental conditions (or different habitats), the species richness of the resulting set can be expected to be higher than if all individuals are drawn from similar environments.
Biodiversity is usually plotted as taxonomic richness of a geographic area, with some reference to a temporal scale. Whittaker [9] described three common metrics used to measure species-level biodiversity, encompassing attention to species richness or species evenness: Species richness - the simplest of the indices available. Simpson index
In contrast to these "mechanistic" explanations, others assert the need to test whether the pattern is simply the result of a random sampling process. [7] Species–area relationships are often evaluated in conservation science in order to predict extinction rates in the case of habitat loss and habitat fragmentation .
The logic behind the derivation of the logseries is varied [15] however Fisher proposed that sampled species abundances would follow a negative binomial from which the zero abundance class (species too rare to be sampled) was eliminated. [1] He also assumed that the total number of species in a community was infinite.
Species richness, or biodiversity, increases from the poles to the tropics for a wide variety of terrestrial and marine organisms, often referred to as the latitudinal diversity gradient. [1] The latitudinal diversity gradient is one of the most widely recognized patterns in ecology. [1] It has been observed to varying degrees in Earth's past. [2]
These are measurement methods which involve estimation based on viewing a specific area of a designated size. [6] The two Semi-Quantitive Abundance ratings used are known as the D.A.F.O.R, and the A.C.F.O.R. [6] The A.C.F.O.R. scale is as follows: A – Species observed is "Abundant" within the given area.
Species distribution can be predicted based on the pattern of biodiversity at spatial scales. A general hierarchical model can integrate disturbance, dispersal and population dynamics. Based on factors of dispersal, disturbance, resources limiting climate, and other species distribution, predictions of species distribution can create a bio ...
Consequently, some macroecological and community patterns cannot be fully expressed by alpha and beta diversity. Due to these two reasons, a new way of measuring species turnover, coined Zeta diversity (ζ-diversity), [12] has been proposed and used to connect all existing incidence-based biodiversity patterns.