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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 :
Resampling methods can be used to bring samples of different sizes to a common footing. [2] Properties of the sample, especially the number of species only represented by one or a few individuals, can be used to help estimating the species richness in the population from which the sample was drawn. [3] [4] [5]
SAD is a measurement of how common, or rare species are within an ecosystem. [5] This allows researchers to assess how different species are distributed throughout an ecosystem. SAD is one of the most basic measurements in ecology and is used very often, therefore many different methods of measurement and analysis have developed.
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]
The technique of rarefaction was developed in 1968 by Howard Sanders in a biodiversity assay of marine benthic ecosystems, as he sought a model for diversity that would allow him to compare species richness data among sets with different sample sizes; he developed rarefaction curves as a method to compare the shape of a curve rather than absolute numbers of species.
Ecologists have proposed a wide range of factors determining the slope and elevation of the species–area relationship. [2] These factors include the relative balance between immigration and extinction, [ 3 ] rate and magnitude of disturbance on small vs. large areas, [ 3 ] predator-prey dynamics, [ 4 ] and clustering of individuals of the ...
The term was introduced by R. H. Whittaker [1] [2] together with the terms beta diversity (β-diversity) and gamma diversity (γ-diversity). Whittaker's idea was that the total species diversity in a landscape (gamma diversity) is determined by two different things, the mean species diversity in sites at a more local scale (alpha diversity) and ...
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.