Decomposing functional β-diversity reveals that low functional β-diversity is driven by low functional turnover in European fish assemblages

TLDR

Biodiversity assessment lacks a unified framework for taxonomic and functional facets, hindering pattern detection. The authors develop a decomposition framework for functional β‑diversity to analyze biogeographical patterns and assess human impacts. The framework was applied to 25 European river basins, decomposing functional β‑diversity into turnover and nestedness components. Functional β‑diversity was lower than taxonomic β‑diversity, driven by reduced functional turnover while nestedness was similar, indicating that species‑poor faunas share functional attributes.

Abstract

Aim One of the main gaps in the assessment of biodiversity is the lack of a unified framework for measuring its taxonomic and functional facets and for unveiling the underlying patterns. Location Europe, 25 large river basins. Methods Here, we develop a decomposition of functional β-diversity, i.e. the dissimilarity in functional composition between communities, into a functional turnover and a functional nestedness-resultant component. Results We found that functional β-diversity was lower than taxonomic β-diversity. This difference was driven by a lower functional turnover compared with taxonomic turnover while the nestedness-resultant component was similar for taxonomic and functional β-diversity. Main conclusions Fish faunas with different species tend to share the same functional attributes. The framework presented in this paper will help to analyse biogeographical patterns as well as to measure the impact of human activities on the functional facets of biodiversity.