Evolution of MHC class I genes in the European badger (Meles meles)

Yung Wa Sin*, Hannah L. Dugdale, Chris Newman, David W. Macdonald, Terry Burke

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)
207 Downloads (Pure)

Abstract

The major histocompatibility complex (MHC) plays a central role in the adaptive immune system and provides a good model with which to understand the evolutionary processes underlying functional genes. Trans-species polymorphism and orthology are both commonly found in MHC genes; however, mammalian MHC class I genes tend to cluster by species. Concerted evolution has the potential to homogenize different loci, whereas birth-and-death evolution can lead to the loss of orthologs; both processes result in monophyletic groups within species. Studies investigating the evolution of MHC class I genes have been biased toward a few particular taxa and model species. We present the first study of MHC class I genes in a species from the superfamily Musteloidea. The European badger (Meles meles) exhibits moderate variation in MHC class I sequences when compared to other carnivores. We identified seven putatively functional sequences and nine pseudogenes from genomic (gDNA) and complementary (cDNA) DNA, signifying at least two functional class I loci. We found evidence for separate evolutionary histories of the alpha 1 and alpha 2/alpha 3 domains. In the alpha 1 domain, several sequences from different species were more closely related to each other than to sequences from the same species, resembling orthology or trans-species polymorphism. Balancing selection and probable recombination maintain genetic diversity in the alpha 1 domain, evidenced by the detection of positive selection and a recombination event. By comparison, two recombination breakpoints indicate that the alpha 2/alpha 3 domains have most likely undergone concerted evolution, where recombination has homogenized the alpha 2/alpha 3 domains between genes, leading to species-specific clusters of sequences. Our findings highlight the importance of analyzing MHC domains separately.

Original languageEnglish
Pages (from-to)1644-1662
Number of pages19
JournalEcology and Evolution
Volume2
Issue number7
DOIs
Publication statusPublished - Jul-2012

Keywords

  • Balancing selection
  • birth-and-death evolution
  • concerted evolution
  • major histocompatibility complex
  • orthology
  • trans-species polymorphism
  • MAJOR HISTOCOMPATIBILITY COMPLEX
  • AMINO-ACID SITES
  • MYCOBACTERIUM-BOVIS
  • EURASIAN BADGERS
  • TRANSSPECIES POLYMORPHISM
  • MOLECULAR PHYLOGENY
  • CONCERTED EVOLUTION
  • POPULATION-DYNAMICS
  • CARNIVORA MAMMALIA
  • POSITIVE SELECTION

Cite this