What is alpha diversity? (2024)

FAQs

What is meant by alpha diversity? ›

Alpha diversity refers to diversity on a local scale, describing the species diversity (richness) within a functional community. For example, alpha diversity describes the observed species diversity within a defined plot or within a defined ecological unit, such as a pond, a field, or a patch of forest.

We measure alpha-diversity as the observed richness (number of taxa) or evenness (the relative abundances of those taxa) of an average sample within a habitat type. We quantify beta-diversity as the variability in community composition (the identity of taxa observed) among samples within a habitat [21].

Alpha diversity measures the species diversity in an ecosystem while beta diversity measures the change in species diversity mainly between two communities or two ecosystems. Whereas, gamma diversity measures the overall biodiversity of a large geographic region.

The average alpha diversity can be found as the mean of diversities by the same groups, and their difference or ratio is an estimate of beta diversity (see Examples).

Estimators of Alpha diversity reveal that there might be some rare species that have not been effectively observed. The purpose of an alpha diversity estimator is to extrapolate from the available observations to the total number of species existing in the community.

Alpha diversity methods include information on either richness, evenness, or both. Here are a few examples: Richness: High richness equals more ASVs or more phylogenetically dissimilar ASVs in the case of Faith's PD. Both: Diversity increases as richness and evenness increase.

Beta diversity is the diversity present between the communities. It is also the rate of replacement of species along a gradient of habitats/communities. Whereas, the local species pool is known as alpha diversity and the diversity present in the ranges of communities is known as Gamma diversity.

Beta diversity: It is species diversity b/w two adjacent ecosystems and is obtained by comparing the number of species unique to each ecosystem.

Alpha diversity (α-diversity) is defined as the mean diversity of species in different sites or habitats within a local scale. This term was coined by Robert Harding Whittaker along with other connected terminologies such as beta diversity (β-diversity) and gamma diversity (γ-diversity).

Alpha diversity is a term used to describe the "within-sample" diversity. It's a measure of how diverse a single sample is, usually taking into account the number of different species observed. Alpha diversity metrics are also often weighted by the abundances at which the individual microbes are observed.

Is alpha diversity and genetic diversity same? ›

Alpha- diversity Within the particular area. Beta-Comparison of diversity between ecosystems. Gamma- overall diversity for different ecosystems within the region. first of all alpha diversity , beta diversity and gamma diversity are not the types of genetic diversity.

The outcomes of species composition across local communities are not identical, hence diversity in the overall species pool or the 'gamma diversity (γ)' is generally much larger than alpha diversity.

alpha diversity metrics ( Figure S2) and the Shapiro-Wilk tests for normality showed that the data were normally distributed. The alpha diversity measures for all samples are presented in Table 2. The mean ratio between observed to expected (Chao1) richness was >0.99 for all samples. ...

Anything more than zero is a good alpha; higher the alpha ratio in mutual fund schemes on a consistent basis, higher is the potential of long term returns. Generally, beta of around 1 or less is recommended.

The alpha value, or the threshold for statistical significance, is arbitrary – which value you use depends on your field of study. In most cases, researchers use an alpha of 0.05, which means that there is a less than 5% chance that the data being tested could have occurred under the null hypothesis.

Alpha diversity actually refers to community and ecosystem diversity. For measuring biodiversity over spatial scales, Whittaker in 1972 described three terms, namely alpha, beta, and gamma diversity.