From alpha to beta functional and phylogenetic redundancy

1. Plot-level redundancy or alpha redundancy is usually defined as the fraction of species diversity not expressed by functional or phylogenetic diversity. Redundancy is zero when all species in one plot are maximally dissimilar from each other. By contrast, redundancy tends to its maximum if the functional or phylogenetic differences between species tend to be minimal.

2. To explore the ecological drivers of community assembly, ecologists also use dissimilarity measures between pairs of plots (a component of beta diversity). Traditional dissimilarity measures summarize compositional differences between pairs of plots based either on species presence and absence data or on species abundances, thus attributing equal distinctiveness between any two species.

3. In the last decades a number of dissimilarity measures which incorporate information on functional or phylogenetic differences among species have been proposed. Based on such improved measures, we can define an index of beta r...