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The Evolution of Highly Variable Immunity Genes Across a Passerine Bird Radiation

Author:
  • Emily O'Connor
  • Maria Strandh
  • Dennis Hasselquist
  • Jan-Åke Nilsson
  • Helena Westerdahl
Publishing year: 2016-02-09
Language: English
Publication/Series: Molecular Ecology
Document type: Journal article
Publisher: Wiley-Blackwell

Abstract english

In order to survive, individuals must be able to recognise and eliminate pathogens. The genes of the Major Histocompatibility Complex (MHC) play an essential role in this process in vertebrates as their diversity affects the repertoire of pathogens that can be recognised by the immune system. Emerging evidence suggests that birds within the parvorder Passerida possess an exceptionally high number of MHC genes. However, this has yet to be directly investigated using a consistent framework, and the question of how this MHC diversity has evolved has not been addressed. We used next generation sequencing to investigate how MHC class I gene copy number and sequence diversity varies across the Passerida radiation using twelve species chosen to represent the phylogenetic range of this group. Additionally, we performed phylogenetic analyses on this data to identify, for the first time, the evolutionary model that best describes how MHC class I gene diversity has evolved within Passerida. We found evidence of multiple MHC class I genes in every family tested, with an extremely broad range in gene copy number across Passerida. There was a strong phylogenetic signal in MHC gene copy number and diversity, and these traits appear to have evolved through a process of Brownian Motion in the species studied, i.e. following the pattern of genetic drift or fluctuating selection, as opposed to towards a single optimal value or through evolutionary ‘bursts’. By characterising MHC class I gene diversity across Passerida in a systematic framework, this study provides a first step towards understanding this huge variation.

Keywords

  • Evolutionary Biology
  • Class I
  • Major Histocompatibility Complex
  • Diversity
  • Evolutionary Model
  • Birds.

Other

Published
  • Centre for Animal Movement Research
  • Avian MHC genes
  • Molecular Ecology and Evolution Lab
  • ISSN: 0962-1083
Helena Westerdahl
E-mail: helena [dot] westerdahl [at] biol [dot] lu [dot] se

Senior lecturer

MEMEG

+46 46 222 36 69

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Research group

Molecular Ecology and Evolution Lab

Projects

Doctoral students and postdocs

Research fellows

Postdocs

Luz Garcia-Longoria

PhD students, main supervisor

Samantha Mellinger

PhD students, assistant supervisor

Gustaf Ekelund Ugge

Helena Westerdahl w house sparrow