Data from: Species traits as drivers of food web structure

The use of functional traits to describe community structure is a
promising approach to reveal generalities across organisms and ecosystems.
Plant ecologists have demonstrated the importance of traits in explaining
community structure, competitive interactions as well as ecosystem
functioning. The application of trait-based methods to more complex
communities such as food webs is however more challenging owing to the
diversity of animal characteristics and of interactions. The objective of
this study was to determine how functional structure is related to food
web structure. We consider that food web structure is the result of 1) the
match between consumer and resource traits, which determine the occurence
of a trophic interaction between them, and 2) the distribution of
functional traits in the community. We implemented a statistical approach
to assess whether or not 35 466 pairwise interactions between soil
organisms are constrained by trait-matching and then used a Procrustes
analysis to investigate correlations between functional indices and
network properties across 48 sites. We found that the occurrence of
trophic interactions is well predicted by matching the traits of the
resource with those of the consumer. Taxonomy and body mass of both
species were the most important traits for the determination of an
interaction. As a consequence, functional evenness and the variance of
certain traits in the community were correlated to trophic complementarity
between species, while trait identity, more than diversity, was related to
network topology. The analysis was however limited by trait data
availability, and a coarse resolution of certain taxonomic groups in our
dataset. These limitations explain the importance of taxonomy, as well as
the complexity of the statistical model needed. Our results outline the
important implications of trait composition on ecological networks,
opening promising avenues of research into the relationship between
functional diversity and ecosystem functioning in multi-trophic systems.