Beta Diversity
How similar the fish communities of different reefs, sites, years or habitats are, and whether they differ by replacing species or by holding fewer of them.
The other Metrics tabs describe one community at a time. This page compares several, the groups you pick under Compare by, and asks how alike their fish communities are and why they differ. Read it from the top. (i) Sampling effort comes first: a group surveyed with more transects records more species by chance alone, and the effort correction compares groups at equal effort. (ii) The pairwise matrix scores every pair of groups, on species lists (Sørensen, Jaccard) or on abundances (Bray-Curtis and the others); the ordination and the dendrogram redraw those scores as a map and a tree, where groups close together are alike. (iii) Turnover and nestedness say why two groups differ: species replacing one another, or one group holding only part of the other's species. Last, distance decay asks whether places farther apart differ more, and the Hill-number partition splits the total diversity (γ) into diversity within groups (α) and between them (β).
Transects per group
Sørensen similarity, rarefied
Select a cell to see which species the two groups share and which each holds alone.
Principal coordinates
Dendrogram
Turnover and nestedness
Distance decay
Hill-number partition
Computing the partition: every group is subsampled and bootstrapped, which takes a few seconds the first time.