Major histocompatibility complex (MHC) genes are the most polymorphic genes in vertebrates and encode molecules that play a crucial role in pathogen resistance. As a result of their diversity, they have received much attention in the fields of evolutionary and conservation biology. Here, we described the genetic variation of MHC class II B (MHCIIB) exon 2 in a wild population of Hume’s pheasant (Syrmaticus humiae), which has suffered a dramatic decline in population over the last three decades across its ranges in the face of heavy exploitation and habitat loss. Twenty-four distinct alleles were found in 73 S. humiae specimens. We found seven shared alleles among four geographical groups as well as six rare MHCIIB alleles. Most individuals displayed between one to five alleles, suggesting that there are at least three MHCIIB loci of the Hume’s pheasant. The dN ⁄ dS ratio at putative antigen-binding sites (ABS) was significantly greater than one, indicating balancing selection is acting on MHCIIB exon 2. Additionally, recombination and gene conversion contributed to generating MHCIIB diversity in the Hume’s pheasant. One to three recombination events and seventy-five significant gene conversion events were observed within the Hume’s pheasant MHCIIB loci. The phylogenetic tree and network analysis revealed that the Hume’s pheasant alleles do not cluster together, but are scattered through the tree or network indicating a trans-species evolutionary mode. These findings revealed the evolution of the Hume’s pheasant MHC after suffering extreme habitat fragmentation.
Natural History Museum of Guangxi, Nanning 530012, People’s Republic of China;College of Life Science and Technology, Yulin Normal University, Yulin 537000, People’s Republic of China;Guangxi Key Laboratory of Rare and Endangered Animal Ecology, College of Life Sciences Guangxi Normal University, Guilin 541004, People’s Republic of China
Recommended Citation:
Weicai Chen,Yongjian Bei,Hanhua Li. Genetic Variation of the Major Histocompatibility Complex (MHC Class II B Gene) in the Threatened Hume’s Pheasant, Syrmaticus humiae[J]. PLOS ONE,2015-01-01,10(1)