FIG. 3.—

Locations of root as inferred from the individual gene families. The backbone tree is the plurality tree depicted in figure 1A, with the PCC7002 genome removed. Numbers on the branches indicate how many gene families support position of the root on that branch (see Materials and Methods on details of finding the root location). Additionally, 35 gene families supported positioning the root on 14 branches that are in conflict with the plurality tree topology and hence cannot be depicted (see supplementary table 3, Supplementary Material online).