Figure 3: Time-calibrated cyanobacteria tree.

The phylogeny shown was estimated based on 135 proteins from 57 taxa. Three calibration points (black circles) were used for the tree presented and were treated as soft bounds. The root of the tree was set with a maximum age of 2,700 Myr ago and a minimum age of 2,320 Myr ago. Divergence time for the ancestor of cyanobacteria UCYN-A1 and UCYN-A2 (highlighted with a grey box) is given with the corresponding values for the posterior 95% confidence intervals in Supplementary Table 2.