Fig. 6.—

An evolutionary tree for kynurenine-3-monooxygenase indicates that some unicellular eukaryotes acquired genes through horizontal transfers. The unrooted Bayesian tree shows posterior probabilities above the branches and PhyML bootstrap values below the branches. Thickened horizontal lines represent 1.0 Bayesian posterior probability. Trees with significantly lower log-likelihood were obtained when monophyly was enforced for all sequences from eukaryotes, from Amoebozoa plus other Unikonta (without Sphaeroforma arctica), from S. arctica plus other Opisthokonta, or from Emiliania huxleyi, Aureococcus anophagefferens, and Perkinsus marinus plus Labyrinthulomycetes and Chlorarachniophyta (i.e., SAR and Haptophyta; fig. 2 and supplementary table S1, Supplementary Material online).