Table 3. Correlations between plant traits and tip-specific speciation rates estimated from the main ExaML species tree.

Each trait is correlated against two estimates of speciation rates using phylogenetic least squares (PGLS) and a simulation-based method (SIM). Node density (ND) and equal split (ES) estimates of speciation rates are strongly correlated (r = 0.767, p<0.001) but differ in relative weighting of recent and more distant evolutionary history. For 1000 sets of randomly generated traits, only three resulted in more than one significant correlation, suggesting that multiple significant tests per trait (bold) are unlikely to arise by chance.

	Nd-pgls	Nd-sim	Es-pgls	Es-sim
Total glucosinolate concentrations	F1,46 = 0.79, p=0.379	rPearson = 0.29, p=0.300	F1,46 = 0.00, p=0.990	rPearson = 0.09, p=0.737
Number of glucosinolate compounds	F1,46 = 1.16, p=0.286	rPearson = 0.23, p=0.412	F1,46 = 0.87, p=0.356	rPearson = 0.14, p=0.603
Total cardenolide concentrations	F1,46 = 0.29, p=0.593	rPearson = 0.25, p=0.373	F1,46 = 0.01, p=0.908	rPearson = 0.23, p=0.398
Number of cardenolide compounds	F1,46 = 5.87, p=0.019	rPearson = 0.53, p=0.030	F1,46 = 1.93, p=0.17	rPearson = 0.42, p=0.093