ML tree showing the common and rare types of SerRS and ThrRS. Branch colors depict Euryarchaeota (red), TACK groups (Thaumarchaeota, Crenarchaeota, Korarchaeota) (orange), Bacteria (blue) and Eukarya (green). More narrow taxonomic designations are bracketed and labeled. Ancestral nodes of rare and common aaRS types within the tree are labeled (A-D). Dotted lines represent branches with <50% BS support; major clades with >80% BS support are labeled with respective BS support values. Italic numbers represent posterior probability (PP) support values from tree reconstruction in PB. Significant conflict between the ML and PB trees is shown by an alternative diagonal branching. The full alignment used for the ML tree contains 201 taxa, an alignment length of 1322 amino acids and was reciprocally rooted using each aaRS family paralog. For the PB reconstruction, a decomposed alignment was used, concatenating global and aaRS family-specific well-aligned sites as identified by GUIDANCE for a total alignment length of 453 amino acids (see methods). Branch lengths depict substitutions/site. (*)PP support value in the alternative PB topology.