The tree is unrooted. Branches with bootstrap support values below 50% were removed. Branch lengths are not shown, for ease of interpretation. Protein domain architecture is not given in order. The ‘Other’ group is all species that are neither animals, choanoflagellates or plants. The tree is largely unresolved, but plant and choanozoan proteins encoding a transmembrane, LRR and TIR domain (dark blue) are never found together in the same resolved clade, supporting their distinct evolutionary histories. ‘Kinase TLRs’ (LRR, transmembrane, Pkinase, TIR; dark red) and ‘Kinase TIRs’ (no transmembrane, Pkinase, TIR; light red) are only found in choanoflagellates.