- 1The distribution of biodiversity at multiple spatial scales has been traditionally investigated through the additive partitioning of γ-biodiversity (regional) into α-(within-site) and β-(among-site) components.
- 2However, this decomposition is almost exclusively applied using species turnover among communities while two communities with no species in common can be very similar because they share some ‘biological’ similarity.
- 3To overcome this limitation, Hardy & Senterre (2007) (J. Ecol., 95, 493–506) presented a new statistical framework partitioning the phylogenetic diversity into α- and β-components using the Rao's quadratic entropy.
- 4We show that their decomposition is correct only when sites have the same total abundance, otherwise it may lead to negative β-diversity values. As an alternative, we provided a general decomposition of the quadratic entropy into α-, β- and γ-diversities.
- 5Synthesis. We suggest that the ‘biological’ turnover quantified by the β-component of the regional quadratic entropy may help, at least, to disentangle dispersal vs. niche influences on biodiversity patterns.