Phylogenetic tree of the marsupial DAB locus in relation to the other MHC II β gene families. The loci DOB, DPB, DQB, DRB are eutherian MHC class II β gene families, DZB is the prototherian family, and DBB and DCB are additional marsupial β gene families. Some branches have been compressed for a better overview. The tree was constructed with the neighbour joining method (Kimura-2-parameter), bootstrap values >50 are indicated (1,000 replications). The scale bar represents genetic distance in nucleotide substitution per site. # following an allele's name indicates a pseudogene. Grmi = Gracilinanus microtarsus, open circle, Main = Marmosops incanus, filled circle; Modo = Monodelphis domestica, in bold; Maeu = Macropus eugenii, Maru = Macopus rufogriseus, Trvu = Trichosurus vulpecula. Chicken = Gallus gallus, Axolotl = Ambystoma mexicanum, Xenopus = Xenopus laevis, Bombina = Bombina bombina and Sphenodon = Sphenodon punctatus.