Phylogeny of class III RNR from eukaryotes together with their most similar bacterial sequences. A PhyML UL3 phylogeny from an alignment of NrdD protein sequences of the class III RNR enzyme from eukaryotic genomes and similar NrdD sequences from complete bacterial genomes. Only the NrdD part of the fused eukaryotic NrdDG proteins was used. The arrow indicates eukaryotic sequences. Large top-level groups from the NCBI taxonomy have been colour-coded, see inset legend, smaller groups are black. Viruses are in italics. The tree is not formally rooted; the pseudoroot is placed so as to be consistent with the global phylogeny in Figure 1d.