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Female reed warblers in social pairs with low MHC dissimilarity achieve higher MHC dissimilarity through random extra-pair mating

Halupka, Lucyna ; Strandh, Maria LU ; Sztwiertnia, Hanna ; Klimczuk, Ewelina ; Hasselquist, Dennis LU ; O'Connor, Emily LU orcid and Westerdahl, Helena LU (2026) In Evolution
Abstract
Major Histocompatibility Complex (MHC) polymorphism is maintained by balancing selection through host-pathogen interactions and mate choice. MHC-based mate choice has been investigated across a wide range of vertebrates, and an established concept is that females should choose a mate with an MHC genotype that is dissimilar to her own to ensure high MHC divergence in her offspring. Here we present evidence from a population of reed warblers, Acrocephalus scirpaceus, that social pairs with extra pair young in their nest have significantly lower MHC dissimilarity than expected by random MHC-based mate choice. Moreover, social pairs with extra pair young in their nest have lower MHC dissimilarity than the potential pairs females could form... (More)
Major Histocompatibility Complex (MHC) polymorphism is maintained by balancing selection through host-pathogen interactions and mate choice. MHC-based mate choice has been investigated across a wide range of vertebrates, and an established concept is that females should choose a mate with an MHC genotype that is dissimilar to her own to ensure high MHC divergence in her offspring. Here we present evidence from a population of reed warblers, Acrocephalus scirpaceus, that social pairs with extra pair young in their nest have significantly lower MHC dissimilarity than expected by random MHC-based mate choice. Moreover, social pairs with extra pair young in their nest have lower MHC dissimilarity than the potential pairs females could form with other males surrounding the social nest. Therefore, females in pairs with low MHC dissimilarity could improve the MHC divergence of her offspring through extra-pair mating. We propose that when the MHC dissimilarity in the social pair is low, any alternative male represents a better genetic prospect for the female in terms of MHC dissimilarity. This scenario generates a pattern of MHC-disassortative extra-pair mating without requiring active MHC-based mate choice. (Less)
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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
in press
subject
in
Evolution
article number
qpag001
publisher
Wiley-Blackwell
external identifiers
  • pmid:41553354
ISSN
1558-5646
DOI
10.1093/evolut/qpag001
language
English
LU publication?
yes
id
1a4025b1-33cf-457a-9a55-8daa4e04c793
date added to LUP
2026-01-26 11:10:00
date last changed
2026-02-03 15:09:02
@article{1a4025b1-33cf-457a-9a55-8daa4e04c793,
  abstract     = {{Major Histocompatibility Complex (MHC) polymorphism is maintained by balancing selection through host-pathogen interactions and mate choice. MHC-based mate choice has been investigated across a wide range of vertebrates, and an established concept is that females should choose a mate with an MHC genotype that is dissimilar to her own to ensure high MHC divergence in her offspring. Here we present evidence from a population of reed warblers, Acrocephalus scirpaceus, that social pairs with extra pair young in their nest have significantly lower MHC dissimilarity than expected by random MHC-based mate choice. Moreover, social pairs with extra pair young in their nest have lower MHC dissimilarity than the potential pairs females could form with other males surrounding the social nest. Therefore, females in pairs with low MHC dissimilarity could improve the MHC divergence of her offspring through extra-pair mating. We propose that when the MHC dissimilarity in the social pair is low, any alternative male represents a better genetic prospect for the female in terms of MHC dissimilarity. This scenario generates a pattern of MHC-disassortative extra-pair mating without requiring active MHC-based mate choice.}},
  author       = {{Halupka, Lucyna and Strandh, Maria and Sztwiertnia, Hanna and Klimczuk, Ewelina and Hasselquist, Dennis and O'Connor, Emily and Westerdahl, Helena}},
  issn         = {{1558-5646}},
  language     = {{eng}},
  month        = {{01}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Evolution}},
  title        = {{Female reed warblers in social pairs with low MHC dissimilarity achieve higher MHC dissimilarity through random extra-pair mating}},
  url          = {{http://dx.doi.org/10.1093/evolut/qpag001}},
  doi          = {{10.1093/evolut/qpag001}},
  year         = {{2026}},
}