What is unweighted UniFrac?
Unweighted UniFrac measures the distance between two communities by calculating the fraction of the branch length in a phylogenetic tree that leads to descendants in either, but not both, of the two communities (Fig. 1A).
Is UniFrac phylogenetic?
UniFrac is a β-diversity measure that uses phylogenetic information to compare environmental samples.
How is UniFrac calculated?
UniFrac measures the amount of evolutionary divergence between these two communities by dividing the length of the purple branches by the total branch length of the tree.
What is Faith’s phylogenetic diversity?
Faith’s phylogenetic diversity (PD), which is defined as the sum of the branch lengths of a phylogenetic tree connecting all species, takes into account phylogenetic differences among species and has found many applications in various research fields.
What is a high beta diversity?
Beta diversity measures the change in diversity of species from one environment to another. So, a high beta diversity index indicates a low level of similarity, while a low beta diversity index shows a high level of similarity.
What is difference between alpha and beta diversity?
While alpha diversity is a measure of microbiome diversity applicable to a single sample, beta diversity is a measure of similarity or dissimilarity of two communities.
Can UniFrac be used as a distance metric for multivariate statistics?
In recent simulations, it was concluded that UniFrac could be used to determine whether communities were significantly different, but should not be used as a distance metric for multivariate statistical analyses.
Is there a weighted version of UniFrac?
Additionally, there is a weighted version of the UniFrac metric which accounts for the relative abundance of each of the taxa within the communities. This is commonly used in metagenomic studies, where the number of metagenomic reads can be in the tens of thousands, and it is appropriate to ‘bin’ these reads into operational…
Does UniFrac count the number of times each sequence is observed?
Since UniFrac does not count the number of times each sequence is observed, these data can still be compared, although the “evenness” component that is a standard measure of diversity ( 27) is not currently represented in UniFrac.
Is UniFrac useful for 16S rRNA gene libraries?
We demonstrate the utility of UniFrac by applying it to published 16S rRNA gene libraries from cultured isolates and environmental clones of bacteria in marine sediment, water, and ice.