Using trophic structure to reveal patterns of trait-based community assembly across niche dimensions

1. Trait-based approaches for studying community assembly have improved understanding of mechanisms; however, the challenge of interpreting process from pattern is complicated by the possibility of multiple mechanisms operating simultaneously. Different traits may influence the assembly process in different ways. Analyzing patterns of functional diversity among co-occurring species for each trait individually may aid interpretation of complex assembly processes; yet, few studies have tested whether patterns vary depending on trait function.
2. We used tropical fish assemblages from the Xingu River, Brazil to test whether traits associated with resource acquisition play a stronger role in niche segregation relative to other traits. First, a null modeling approach was used to determine how trait distributions within local assemblages deviated from expectations under random assembly. Then, correlations between functional traits and stable isotope ratios (δ13C, δ15N) were used as a measure...