Testing for common ancestry of E6 and E7 on reduced dataset 1. The test was performed using the software Bali-Phy on the concatenated E6 and E7 amino acid sequences as well as on E6 and E7 separately. The log marginal likelihoods (P(data|M)) are indicated for the Common Ancestry (CA) model (H0) and the alternative Independent Origin (IO) models (H1–H7). The Bayes factor for CA is calculated as ΔBF = log [Prob(CA)] − log [Prob(IO)], such that positive values favour CA and negative values indicate IO.