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

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 (a) and among-communities (b) components, in analogy to Whittaker's classical a and b species diversity concept. In light of ecological null models, we test and discuss two algorithms as a framework to measure a and b 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 a 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 (a ) b). 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.

The relationships between structural and functional diversity within and among macrophyte communities in lakes

“…2). Similar results have been obtained by de Bello et al (2009) for plant communities in pastures along an altitude gradient in Spain. It is worth noting that the β Simpson diversity index and β species richness are different measures of species turnover among communities (Pavoine et al, 2004).…”

Do community-weighted mean functional traits reflect optimal strategies?

“…[5,16,17]. For instance, de Bello et al [16] found that within-site variation of SLA accounted for approximately 90% of the total observed variation across regional climatic gradients.…”

“…[5,16,17]. For instance, de Bello et al [16] found that within-site variation of SLA accounted for approximately 90% of the total observed variation across regional climatic gradients. At a larger scale, more than one-third of the total global variation in SLA occurs within areas of similar abiotic conditions, as opposed to among sites that vary with respect to climate variables [5].…”

Functional Diversity and Traits Assembly Patterns of Benthic Macrofaunal Communities in the Southern North Sea

“…d ij is the trait dissimilarity between each pair of taxa i and j measured as Euclidean distance. Accordingly, FD RAO is the sum of the trait dissimilarities among all possible pairings of taxa, weighted by the relative abundance of the taxa (de Bello et al 2009). FD RAO was calculated separately for each of the 11 biological traits and summed up for the entire assemblage of a site (Darr et al 2014;van der Molen et al 2013).…”