Hypothetical examples of how examining FDα-traits and FDβ-traits shows support for the SDH, even when PD shows an unexpected pattern.

For each example (A-C), individual species are represented by symbols at the tips of the phylogenetic tree; the shape of the symbols represents beta traits, the color of the symbols represents alpha traits, and communities are represented by rectangles. In each example, we show two communities, one at the stressful and one at the benign end of the stress gradient. In case A, the alpha traits are labile while the beta traits are conserved; therefore PD tracks the pattern observed for FDβ-traits, so that competition is not evident from the PD pattern at the benign end of the gradient. In the opposite case (B), alpha traits are conserved but beta traits are not; therefore PD tracks the alpha trait pattern and does not show clustering consistent with environmental filtering at the stressful end of the gradient. In case C, PD shows an unexpected pattern because neither alpha nor beta traits have strong phylogenetic signal and competition shows a different pattern than the one that is generally expected, with strong competition causing competitive exclusion 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. https://doi.org/10.3897/oneeco.1.e9501