Gene trees of exons 4–8 of primate MHC class I alleles showing the genus-specific distribution of MHC class I sequences in the Callitrichinae. Test of significance of internal branches: ∗, P < 0.05; ∗∗, P < 0.01; ∗∗∗, P < 0.001. Saoe, Saguinos oedipus; Safu, Saguinos fuscicollis; caja, callithrix jacchus; Lero, Leontopithecos rosalia; Sasc; Saimiri sciureus; Aotr, Aotus trivirgatus; Atbe, Ateles belzebuth; Pipi, Pithecia pithecia; Gogo, Gorilla gorilla; Hyla, Hylobates lar.