The phylogeny of 10 species used in this study

To verify the phylogenetic structure of these species, for each of the 10 species we searched GenBank for matK gene sequences, which are commonly used in published plant phylogenies (Cadotte 2013). We included a gymnosperm Platycladus orientalis as the out-group species. Sequences were aligned with ClustalW (Thompson et al. 2002). The Bayesian phylogeny was reconstructed using BEAST version v1.8.2 (Drummond et al. 2012). The Bayesian MCMC chain was run for one million generations, and convergence was checked using Tracer version v1.6.0 (http://beast.bio.ed.ac.uk/Tracer). The maximum clade credibility tree was used to quantify phylogenetic pattern by TreeAnnotator version v1.8.2 (Drummond et al. 2012)