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Gaczorek TS, Chechetkin M, Dudek K, Caeiro-Dias G, Crochet PA, Geniez P, Pinho C, Babik W. Widespread introgression of MHC genes in Iberian Podarcis lizards. Mol Ecol 2023. [PMID: 37143304 DOI: 10.1111/mec.16974] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/24/2023] [Accepted: 04/12/2023] [Indexed: 05/06/2023]
Abstract
Major histocompatibility complex (MHC) genes are crucial for the adaptive immune response of jawed vertebrates. Their variation, reaching extreme levels, is driven mainly by an arms race between hosts and pathogens. One hypothesised mechanism contributing to MHC polymorphism is adaptive introgression, the exchange of genetic variants between hybridising species favoured by selection, yet its effect on MHC variation is poorly understood. Detection of adaptive MHC introgression, though challenging, may be facilitated by the analysis of species complexes forming multiple hybrid zones. Here, we investigated MHC introgression in six hybrid zones formed by seven species of Podarcis lizards inhabiting the Iberian Peninsula. To differentiate adaptive introgression from neutral introgression, we compared the patterns of gene exchange in MHC and genome-wide markers. We found elevated sharing of MHC alleles in the proximity of contact beyond the areas of detectable genome-wide admixture in most hybrid zones and, in half of them, asymmetric MHC exchange. In general, the elevated MHC allele sharing between species pairs with abutting ranges compared to geographically isolated species pairs also supports the prevalence of introgression. Collectively, our results demonstrate widespread MHC introgression in the Iberian Podarcis complex and suggest its adaptiveness. Contrary to previous results from Triturus newts, we did not observe differences in the rate of introgression between MHC classes. Our work adds support to the emerging view of adaptive introgression as a key mechanism shaping MHC diversity. It also raises questions about the effect of elevated MHC variation and factors leading to the asymmetry of adaptive introgression.
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Affiliation(s)
| | - Mateusz Chechetkin
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Katarzyna Dudek
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Guilherme Caeiro-Dias
- Department of Biology and Museum of Southwestern Biology, University of New Mexico, Albuquerque, New Mexico, USA
| | | | - Philippe Geniez
- CEFE, EPHE-PSL University, Univ Montpellier, CNRS, IRD, Biogéographie et Ecologie des Vertébrés, Montpellier, France
| | - Catarina Pinho
- Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, Vairão, Portugal
| | - Wiesław Babik
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
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