(A) Phylogenetic reconstruction was performed using neighbor-joining, maximum-likelihood, and maximum-parsimony methods. Shown is the neighbour-joining tree, with midpoint rooting and black, grey and white circles indicating ≥95, 80 and 60% bootstrap support, respectively, with all three methods. For the analysis exon 4, encoding the α3 domain, and the non-coding regions in the 5′ and 3′ of the gene were excluded. (B) Schematic showing the phylogenetic relationships between the MHC-A, MHC-H and MHC-AL and related MHC class I gene sequences. Equivalent segments between or within species share the same colors. These conclusions are based on the results from domain-by-domain phylogenetic analyses, and recombination detection methods (see Methods). HLA-A2 and HLA-A3 refer to the two major lineages of HLA-A alleles. *, MHC-A/AL group. **, outgroup to both MHC-A and -AL. Mamu, Macaca mulatta; Popy, Pongo pygmaeus; Patr, Pan troglodytes; Gogo, Gorilla gorilla.