关键词: 野猪, DRB exon 2, 遗传变异, 平衡选择, 系统发生

Abstract: In present study,the genetic variances of SLA DRB exon 2 of Chinese wild boar (Sus scrofa) were analyzed, and the effects of selection at the locus in different geographic environments were addressed as well. The sequence analysis showed that the rates of nonsynonymous substitutions per nonsynonymous site was 2.95 times higher than the rates of synonymous substitutions per synonymous sites at the antigen binding sites. The results indicated that balancing selection may have acted on the antigen binding sites in the evolution of Chinese wild boars. The phylogeny analysis based on nucleotide variation revealed that 15 alleles form Chinese wild boars formed one cluster,and there was no trans-species polymorphism. However,the high similarity of amino acids sequence of SLA-DRB* nnu6 and human DRB exon 2 may indicate convergent evolution under same natural selection pressure. The results showed that genetic diversity of SLA DRB exon 2 in S. s. ussuricus was significantly lower than S s moupinensis and S. s.chirodonta, which may indicated a consistent relation ship between SLA diversity and parasite or other factors in different climatic and geographical environment.

Key words: Balancing selection, DRB exon 2, Genetic variation, Phylogeny, Sus scrofa