DOI: 10.5061/dryad.b28p8
title: Data from: Individual-level trait diversity concepts and indices to comprehensively describe community change in multidimensional trait space

description: Global environmental change can influence ecosystem processes directly or
 through changes in the trait composition of natural communities. Traits
 are individual-level features of organisms, and theory predicts that
 diversity in traits should relate to ecosystem processes. Validated
 indices that account for both intra- and interspecific trait variation in
 multidimensional trait space are lacking. In this article, we highlight
 how an individual-level perspective requires new concepts for trait
 diversity (TD) and we validate a set of measures suitable to study trait
 richness, evenness and divergence at the individual scale. First, we
 tested a selection of multivariate indices for trait richness, evenness
 and divergence from the literature (FRic, FEve, FDis and the Rao
 coefficient) using simulated and real individual-level data. We compared
 the observed changes in the tested indices with those predicted from their
 expected/required behaviour (i.e. increase or decrease under specific
 manipulation of community trait structure) and found unsatisfactory
 results only for FRic and FEve, whereas FDis and the Rao coefficient
 showed the expected changes. Therefore, we propose two novel concepts and
 related indices for individual-level trait richness (TOP = trait onion
 peeling) and evenness (TED = trait even distribution). TOP represents the
 sum of all successive convex hull areas touching all individuals (points)
 within a multidimensional trait distribution. TED is a measure of how
 evenly distributed are individuals within the multidimensional trait
 space. It is calculated comparing the probability distributions of
 pairwise distances between individuals and between points of a perfectly
 even reference distribution. We tested TOP and TED on the same simulated
 and real data as above, and results indicated appropriate behaviour for
 TOP (trait richness) and TED (trait evenness). By validating TD indices in
 an individual-level context, this study contributes to the expansion of
 functional ecology towards individual-level dynamics. Future comprehensive
 investigations of individual trait differences in natural communities may
 improve our understanding of the pathways by which environmental changes
 affect ecosystem functioning through biodiversity change.
description: Artificial test
 scenarios for TD indicesThose are artificial
 data (2-D, 3-D and 8-D) generated with the software R. Each row represents
 an individual organism, each column represents an hypothetical trait.
 Additional information can be found in the paragraph "Artificial test
 scenarios for TD indices" in the section "Materials and
 methods".Artificial
 data.zipTest scenarios for TD
 indices using real dataThose are real data
 (8-D) from 15 samples collected in Lake Zürich (Switzerland) during spring
 2009 (Pomati et al. 2013). Each row represents an individual organism,
 each column represents a trait (principal component calculated using 46
 descriptors of 3-D structure and fluorescence profile for each
 phytoplankton cell or colony). Additional information can be found in the
 paragraph "Test scenarios for TD indices using real data" in the
 section "Materials and methods".Real
 data.zip