Predicted effects of interspecific competition and environmental filtering on FD and PD. 

In Figure 1A, individual species are represented by symbols at the tips of the phylogenetic tree, the shapes of the symbols indicate different trait states, and rectangles represent communities. In this example, the trait is conserved on the phylogeny, such that closely related species tend to have the same traits (shapes). Figure 1B shows the observed PD or FD for each community compared to the distribution of values predicted by the null model; this predicted value is then converted into a standard effect size (SES) relating to the mean of the null model distribution (Figure 1C). Environmental filtering selects for species with similar traits (Community A in Figure 1A), causing functional or phylogenetic clustering (point A in Figure 1C), while interspecific competition limits similarity between co-occurring species resulting in different trait states (Community C in Figure 1A) and functional or phylogenetic overdispersion (point C in Figure 1C). PD or FD that is no different from random expectation can also occur (Community B in Figure 1A, point B in Figure 1C).

  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.