Phylogenetic trees of the S. chinensis DQB (a) and DRB (b) alleles. Alleles of S. chinensis are indicated with arrows. Other homologous cetacean sequences available from GenBank were included. DQB sequences: Yangtze River dolphin (L. vexillifer, AY177150-53), Burmeister’s porpoise (P. spinipinnis, DQ914412), Vaquita porpoise (P sinus, DQ914412), Harbor porpoise (P. phocoena, AB164211), Risso’s dolphin (G. griseus, AB164222), Bottlenose dolphin (T. truncatus, AB164221), Hector’s dolphin (C. hectori, DQ354628-29), Pacific white-sided dolphin (L. obliquidens, AB164224-25), Irrawaddy dolphin (O. brevirostris, AB164223), Indo-Pacific Bottlenose dolphin (T. aduncus, EU698973-77), Guyana river dolphin (S. guianensis, FJ848543-44), Beluga whale (D. leucas, DLU16988-90), Narwhal (M. monoceros, U16991), Saddleback dolphin (D. delphis, AB164220), Bowhead whale (B. mysticetus, DQ354623-25), Fin whale (B. physalus, DQ300261-63), Grey whale (E. robustus, DQ354635-36) and Human (H. sapiens, NM001243962). DRB sequences: Indo-Pacific Bottlenose dolphin (T. aduncus, EF507868-74), Hector’s dolphin (C. hectori, DQ354675), Bottlenosed dolphin (T. truncatus, KJ722698-709), Indo-Pacific Finless porpoise (N. phocaenoides, FJ416157-70), Narwhal (M. monoceros, AF012939-41), Beluga whale (D. leucas, AF012930-37), Blue whale (B. musculus, DQ354666-68), Bowhead whale (B. mysticetus, DQ354669-71), Grey whale (E. robustus, DQ354678), Fin whale (B. physalus, DQ354672-74), Wild goat (C. aegagrus, Z92716), and American bison (B. bison, DQ353805). The Bayesian posterior probabilities of phylogenetic trees larger than 0.5 are indicated above the branches.