Figure 2

Dated phylogeny of Hypericaceae detailing historical biogeography. (a) Present occurrence of species is marked at the tips of the tree using the color code defined in the map top right. Multiple occurrences are indicated. Historical distribution of ancestral populations is given at nodes in the tree (ancestral areas estimated under the M1 model). Node bars indicate the 95% highest posterior density (HPD) produced in divergence time estimation A. Vertical bars define the clades used to assign species-richness in the diversification rates analysis. (b) Comparison of ancestral areas optimized for the Hypericum crown node under two DEC models, the stratified (M1) and the uncostrained (M2). Maps illustrate the reconstructed distribution of ancestral populations and bar charts the likelihood of range optimization (expressed by AIC weights w _i ; WP, western Palearctic; NA, North America). Global temperature (oxygen-isotope curve as a proxy for temperature [11]) is given below the geological time scale. Grey vertical bars indicate major climatic events (EECO, Early-Eocene Climatic Optimum; TEE, Terminal Eocene Event; MMCO, Mid-Miocene Climatic Optimum; Ma, million years ago). Note that the cold adapted Hypericum lineage splits form its tropical sister and starts to diversify during periods of climate cooling.