Partitioning of functional diversity reveals the scale and extent of trait convergence and divergence

Authors

  • Francesco De Bello,

    Corresponding author
    1. Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, 38041 Grenoble, France
    2. Laboratory of Plant Ecology and Forest Botany, Forestry and Technology Centre of Catalonia, E-28240 Solsona, and Agronomical Engineering School, University of Lleida, E-25198 Lleida, Spain
      *Corresponding author; E-mail fradebello@ctfc.es
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  • Wilfried Thuiller,

    1. Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, 38041 Grenoble, France
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  • Jan Lepš,

    1. Department of Botany, Faculty of Sciences, University of South Bohemia
    2. Institute of Entomology, Czech Academy of Sciences, CZ-37005 České Budějovice, Czech Republic
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  • Philippe Choler,

    1. Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, 38041 Grenoble, France
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  • Jean-Christophe Clément,

    1. Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, 38041 Grenoble, France
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  • Petr Macek,

    1. Department of Botany, Faculty of Sciences, University of South Bohemia
    2. Institute of Botany, Czech Academy of Sciences, CZ-37982 Třebon, Czech Republic
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  • Maria-Teresa Sebastià,

    1. Laboratory of Plant Ecology and Forest Botany, Forestry and Technology Centre of Catalonia, E-28240 Solsona, and Agronomical Engineering School, University of Lleida, E-25198 Lleida, Spain
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  • Sandra Lavorel

    1. Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, 38041 Grenoble, France
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  • Coordinating editor: N. Mason.

*Corresponding author; E-mail fradebello@ctfc.es

Abstract

Questions: Trait differentiation among species occurs at different spatial scales within a region. How does the partitioning of functional diversity help to identify different community assembly mechanisms?

Location: Northeastern Spain.

Methods: Functional diversity can be partitioned into within-community (α) and among-communities (β) components, in analogy to Whittaker's classical α and β species diversity concept. In light of ecological null models, we test and discuss two algorithms as a framework to measure α and β functional diversity (the Rao quadratic entropy index and the variance of trait values). Species and trait (specific leaf area) data from pastures under different climatic conditions in NE Spain are used as a case study.

Results: The proposed indices show different mathematical properties but similarly account for the spatial components of functional diversity. For all vegetation types along the climatic gradient, the observed α functional diversity was lower than expected at random, an observation consistent with the hypothesis of trait convergence resulting from habitat filtering. On the other hand, our data exhibited a remarkably higher functional diversity within communities compared to among communities (α≫β). In contrast to the high species turnover, there was a limited functional diversity turnover among communities, and a large part of the trait divergence occurred among coexisting species.

Conclusions: Partitioning functional diversity within and among communities revealed that both trait convergence and divergence occur in the formation of assemblages from the local species pool. A considerable trait convergence exists at the regional scale in spite of changes in species composition, suggesting the existence of ecological redundancy among communities.

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