Neighbor-joining trees. (A) based on the mtDNA control region of five reptile and one bird species. (B) based on the MHC class I based on the same species ( Node values (in %) are obtained from 1000 bootstraps). Although (A) shows species clustered together, (B) demonstrates trans-species polymorphism of the MHC class I gene in reptiles.
Stiebens et al. BMC Evolutionary Biology 2013 13:95 doi:10.1186/1471-2148-13-95