Environmental vs. biotic filtering: what if species traits contribute to both?

This study introduced a novel approach to explore the contribution of species traits to environmental and biotic filtering and, in turn, to community assembly. This approach assumes that a species trait can be associated with both the α component of the niche (describing resource use within communities) and its β component (describing position along environmental gradients). Using data from 26 lacustrine fish communities in the Yangtze River basin, China, and a series of traits based on large-scale habitat preference, trophic resources use, micro-habitat partitioning, and predation, we observed that all traits were over-dispersed within communities, the signature of environmental filtering. However, besides this dominant pattern, we observed that species dissimilar in traits related to resource use or habitat partitioning and similar in habitat requirement were more likely to coexist, as niche theory predicts. Acknowledging the dual role of traits offers a more nuanced understanding of community assembly rules.