High similarity at three MHC loci between the baiji and finless porpoise: trans-species or convergent evolution?
Two DRA alleles and six MHC-I alleles were identified from a group of 15 baiji (Lipotes vexillifer), the most threatened cetacean in the world. Little sequence variation was detected at the DRA locus but extensive variation at the MHC-I locus. In combination with data at the DQB locus previously reported, three MHC loci exon 2 of the baiji all revealed striking similarity with those of the finless porpoise. Especially, some identical alleles shared by both species at the MHC-I and DQB loci suggested the convergent evolution as a consequence of common adaptive solutions to similar environmental pressures in the Yangtze River. As for DRA locus, the identity alleles were shared not only by baiji and finless porpoise but by some other cetacean species of the families Phocoenidae and Delphinidae, suggesting trans-species evolution on this gene.
Xu
Shixia
S
Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210097, China.
Chen
Bingyao
B
Zhou
Kaiya
K
Yang
Guang
G
D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D004247:DNA / Q000302:isolation & purification; D014644:Genetic Variation; D008285:Major Histocompatibility Complex / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D019576:Porpoises / Q000235:genetics* / Q000276:immunology; D011995:Recombination, Genetic; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
D004247:DNA