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.利用功能性状（functional traits）描述群落结构，是揭示不同生物类群与生态系统共性的极具前景的研究路径。植物生态学家已证实，性状在解释群落结构、种间竞争作用以及生态系统功能方面的重要意义。然而，由于动物特征与种间相互作用的多样性，将基于性状的研究方法应用于食物网等更为复杂的群落时，仍面临诸多挑战。本研究旨在探究功能结构与食物网结构之间的关联。我们认为，食物网结构由两方面因素共同决定：1）消费者与资源性状的匹配程度，该因素决定了二者间营养相互作用的发生；2）群落内功能性状的分布格局。我们采用了统计学方法，首先评估土壤生物间的35466对两两相互作用是否受性状匹配的约束，随后通过普氏分析（Procrustes analysis）探究48个样地中功能指数与网络属性间的相关性。研究结果显示，通过匹配消费者与资源的性状，可以较好地预测营养相互作用的发生情况。两类物种的分类学地位与体质量，是决定相互作用能否发生的关键性状。由此可见，群落内的功能均匀度与部分性状的方差，与物种间的营养互补性呈相关关系；而相较于性状多样性，性状属性本身与网络拓扑结构的关联更为紧密。不过，本研究仍受限于性状数据的可获得性，且数据集内部分类群的分类分辨率较为粗糙。上述局限性也解释了为何分类学地位会表现出较强的解释力，以及为何需要构建复杂度较高的统计模型。本研究结果凸显了性状组成对生态网络的重要影响，为多营养级系统中功能多样性与生态系统功能间的关联研究开辟了颇具前景的方向。