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Species evenness is the relative number of individuals of each species in a given area. [1] Species richness [2] is the number of species present in a given area. Species diversity [3] is the relationship between species evenness and species richness. There are many ways to measure biodiversity within a given ecosystem.
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.
Richness R simply quantifies how many different types the dataset of interest contains. For example, species richness (usually noted S) is simply the number of species, e.g. at a particular site. Richness is a simple measure, so it has been a popular diversity index in ecology, where abundance data are often not available. [7]
As a result, larger species are able to survive on a lower quality diet than smaller species. For example, grazing animals make up for their poor quality diet by digesting food longer and are able to extract more energy from it (Maurer et al. 1992 [7]). Smaller species tend to specialize in a habitat that can provide them with a high quality diet.
For example, the Andean region of Peru is a centre of origin for certain tuber species, and over 1,483 varieties of these species can be found there. Genetic diversity is important as different genes give rise to important traits, such as nutrient composition, hardiness to different environments, resistance to pests, or ample harvests. [ 9 ]
This equilibrium was thought to occur because the climax community is composed of species best adapted to average conditions in that area. The term is sometimes also applied in soil development. Nevertheless, it has been found that a "steady state" is more apparent than real, particularly across long timescales.
Species evenness is the relative number of individuals of each species in a given area. [181] Species richness [182] is the number of species present in a given area. Species diversity [183] is the relationship between species evenness and species richness. There are many ways to measure biodiversity within a given ecosystem.
In ecology, rarefaction is a technique to assess species richness from the results of sampling. Rarefaction allows the calculation of species richness for a given number of individual samples, based on the construction of so-called rarefaction curves. This curve is a plot of the number of species as a function of the number of samples.