Interspecific introgression of MHC genes in Triturus newts: Evidence from multiple contact zones

The major histocompatibility complex (MHC) genes are central to the adaptive immune response in vertebrates. Selection generally maintains high MHC variation because the spectrum of recognized pathogens depends on MHC polymorphism. Novel alleles favoured by selection originate by interallelic recomb...

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Bibliographic Details
Published in:Molecular ecology 2023-02, Vol.32 (4), p.867-880
Main Authors: Gaczorek, Tomasz S., Marszałek, Marzena, Dudek, Katarzyna, Arntzen, Jan W., Wielstra, Ben, Babik, Wiesław
Format: Article
Language:English
Subjects:
Adaptive immunity
adaptive introgression
Alleles
Amphibians
Animals
Divergence
Exons
Genes
Genomes
Hybrid zones
hybridization
Hybridization, Genetic
Immune response
Interspecific
Major histocompatibility complex
Mutation
Original
ORIGINAL ARTICLES
Phylogeny
Polymorphism
Recombination
Salamandridae - genetics
Triturus
Triturus - genetics
Vertebrates
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Summary:The major histocompatibility complex (MHC) genes are central to the adaptive immune response in vertebrates. Selection generally maintains high MHC variation because the spectrum of recognized pathogens depends on MHC polymorphism. Novel alleles favoured by selection originate by interallelic recombination or de novo mutations but may also be acquired by introgression from related species. However, the extent and prevalence of MHC introgression remain an open question. In this study, we tested for MHC introgression in six hybrid zones formed by six Triturus newt species. We sequenced and genotyped the polymorphic second exons of the MHC class I and II genes and compared their interspecific similarity at various distances from the centre of the hybrid zone. We found evidence for introgression of both MHC classes in the majority of examined hybrid zones, with support for a more substantial class I introgression. Furthermore, the overall MHC allele sharing outside of hybrid zones was elevated between pairs of Triturus species with abutting ranges, regardless of the phylogenetic distance between them. No effect of past hybrid zone movement on MHC allele sharing was found. Finally, using previously published genome‐wide data, we demonstrated that MHC introgression was more extensive than genome‐wide introgression, supporting its adaptive potential. Our study thus provides evidence for the prevalence of MHC introgression across multiple Triturus hybrid zones, indicating that MHC introgression between divergent hybridizing species may be widespread and adaptive.
ISSN:0962-1083
1365-294X
DOI:10.1111/mec.16804