The phylogenetic history of rbsL, urtA, and rbsS. The presence of each gene in each branch in the phylogenetic tree is illustrated with a colored circle, with the circle's diameter scaled to denote the probability of presence. (A) rbsL and rbsS evolutionary histories. (B) urtA and rbsS evolutionary histories. The long branch leading to Archaea (bottommost clade) was reduced in size for graphical purposes.