Fig. S16
Test for episodic positive selection on ARG2 coding sequences. Branch lengths are scaled to the expected number of substitutions/nucleotide and Branch colour indicates the type of selection (dN/dS or ω) with red corresponding to positive or diversifying selection (ω > 5), blue to purifying selection (ω = 0), and grey to neutral evolution (ω = 1). The proportion of each colour on a branch represents the fraction of the sequence undergoing the corresponding class of selection. Thick branches would indicate statistical support for positive selection. Note that there is no evidence for selection in ARG2 within the vertebrate tree.