Blood parasites shape extreme major histocompatibility complex diversity in a migratory passerine

Research output: Contribution to journalArticle


Pathogens are one of the main forces driving the evolution and maintenance of the highly polymorphic genes of the vertebrate major histocompatibility complex (MHC). Although MHC proteins are crucial in pathogen recognition, it is still poorly understood how pathogen-mediated selection promotes and maintains MHC diversity, and especially so in host species with highly duplicated MHC genes. Sedge warblers (Acrocephalus schoenobaenus) have highly duplicated MHC genes, and using data from high-throughput MHC genotyping, we were able to investigate to what extent avian malaria parasites explain temporal MHC class I supertype fluctuations in a long-term study population. We investigated infection status and infection intensities of two different strains of Haemoproteus, that is avian malaria parasites that are known to have significant fitness consequences in sedge warblers. We found that prevalence of avian malaria in carriers of specific MHC class I supertypes was a significant predictor of their frequency changes between years. This finding suggests that avian malaria infections partly drive the temporal fluctuations of the MHC class I supertypes. Furthermore, we found that individuals with a large number of different supertypes had higher resistance to avian malaria, but there was no evidence for an optimal MHC class I diversity. Thus, the two studied malaria parasite strains appear to select for a high MHC class I supertype diversity. Such selection may explain the maintenance of the extremely high number of MHC class I gene copies in sedge warblers and possibly also in other passerines where avian malaria is a common disease.


  • Aleksandra Biedrzycka
  • Wojciech Bielański
  • Adam Ćmiel
  • Wojciech Solarz
  • Tadeusz Zajac
  • Magdalena Migalska
  • Alvaro Sebastian
  • Helena Westerdahl
  • Jacek Radwan
External organisations
  • Institute of Nature Conservation of the Polish Academy of Sciences
  • Adam Mickiewicz University in Poznań
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Biochemistry and Molecular Biology
  • Ecology


  • Acrocephalus schoenobaenus, Allele frequency changes, Avian malaria, Balancing selection, Copy number variation, Major histocompatibility complex diversity, Sedge warbler
Original languageEnglish
JournalMolecular Ecology
Issue number11
Publication statusPublished - 2018
Publication categoryResearch