Fig. 2.

Consistency in the influence of global cooling on rapid speciation across Orchidoideae. The estimated historical speciation rate curve for the whole tree (red line with blue 95% CI) is plotted alongside the curve of estimated mean global paleotemperature (δ¹⁸O, black line) (A). A histogram of the DCCA coefficients used to infer the mean correlation coefficient across the whole tree (B). The estimated historical speciation rate curves of subclades Diurideae (C), Cranichideae (D), and Orchideae/Diseae (E) are reported with mean correlation coefficients indicated (all are consistently negative and significant at P < 0.0001).