Prediction of the Stress Dominance Hypothesis for FDα-traits, FDβ-traits, and PD. 

Horizontal axis represents a gradient of environmental stress. At the harsh end of the gradient, environmental filtering is strongest, so PD is clustered (negative standard effect size). At the benign end of the gradient, competition becomes more important and results in coexistence of functionally and phylogenetically distinct taxa. Thus PD is overdispersed (positive standard effect size). Because it only reflects traits related to competition, FDα-traits would not show clustering at the harsh end of the gradient; similarly, because it only includes traits related to environmental filtering, FDβ-traits would not show overdispersion at the benign end of the gradient.

  Part of: Lopez B, Burgio K, Carlucci M, Palmquist K, Parada A, Weinberger V, Hurlbert A (2016) A new framework for inferring community assembly processes using phylogenetic information, relevant traits and environmental gradients. One Ecosystem 1: e9501.