title: Tracing evolutionary relicts of positive selection on eight malaria-related immune genes in mammals.
abstract: Plasmodium-induced malaria widely infects primates and other mammals. Multiple past studies have revealed that positive selection could be the main evolutionary force triggering the genetic diversity of anti-malaria resistance-associated genes in human or primates. However, researchers focused most of their attention on the infra-generic and intra-specific genome evolution rather than analyzing the complete evolutionary history of mammals. Here we extend previous research by testing the evolutionary link of natural selection on eight candidate genes associated with malaria resistance in mammals. Three of the eight genes were detected to be affected by recombination, including TNF-α, iNOS and DARC. Positive selection was detected in the rest five immunogenes multiple times in different ancestral lineages of extant species throughout the mammalian evolution. Signals of positive selection were exposed in four malaria-related immunogenes in primates: CCL2, IL-10, HO1 and CD36. However, selection signals of G6PD have only been detected in non-primate eutherians. Significantly higher evolutionary rates and more radical amino acid replacement were also detected in primate CD36, suggesting its functional divergence from other eutherians. Prevalent positive selection throughout the evolutionary trajectory of mammalian malaria-related genes supports the arms race evolutionary hypothesis of host genetic response of mammalian immunogenes to infectious pathogens.
authors.affiliation: Department of Life Science, National Taiwan Normal University, Taipei, Taiwan, Republic of China.
authors.forename: Bing-Hong
authors.initials: BH
authors.lastname: Huang
authors.affiliation: Department of Life Science, National Taiwan Normal University, Taipei, Taiwan, Republic of China pcliao@ntnu.edu.tw.
authors.forename: Pei-Chun
authors.initials: PC
authors.lastname: Liao
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D005075:Biological Evolution; D003062:Codon / Q000235:genetics; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics*; D008288:Malaria / Q000235:genetics*; D008322:Mammals / Q000235:genetics* / Q000276:immunology*; D010802:Phylogeny; D010961:Plasmodium / Q000235:genetics; D011323:Primates; D011995:Recombination, Genetic; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology
chemical_list: D003062:Codon
keywords: Eutherian; Plasmodium; evolutionary arms race; functional divergence; immunogenes; malaria; positive selection; recombination