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Reproductive isolation in a three‐way contact zone

Dean, Laura L.; Whiting, James R.; Jones, Felicity C.; MacColl, Andrew D. C.

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Authors

Profile image of LAURA DEAN

Dr LAURA DEAN LAURA.DEAN@NOTTINGHAM.AC.UK
Senior Technical Specialist

James R. Whiting

Felicity C. Jones



Abstract

Contact zones between divergent forms within a species provide insight into the role of gene flow in adaptation and speciation. Previous work has focused on contact zones involving only two divergent forms, but in nature, many more than two populations may overlap simultaneously and experience gene flow. Patterns of introgression in wild populations are, therefore, likely much more complicated than is often assumed. We begin to address this gap in current knowledge by investigating patterns of divergence and introgression across a complex natural contact zone. We use phenotypic and genomic data to confirm the existence of a three-way contact zone among divergent freshwater resident, saltwater resident and saltwater migratory three-spined stickleback (Gasterosteus aculeatus) on the island of North Uist, Scottish Western Isles. We find evidence for hybridization, mostly between saltwater resident and saltwater migratory forms. Despite hybridization, genomic analyses reveal pairwise islands of divergence between all forms that are maintained across the contact zone. Genomic cline analyses also provide evidence for selection and/or hybrid incompatibilities in divergent regions. Divergent genomic regions occur across multiple chromosomes and involve many known adaptive loci and several chromosomal inversions. We also identify distinct immune gene expression profiles between forms, but no evidence for transgressive expression in hybrids. Our results suggest that reproductive isolation is maintained in this three-way contact zone, despite some hybridization, and that reduced recombination in chromosomal inversions may play an important role in maintaining this isolation.

Citation

Dean, L. L., Whiting, J. R., Jones, F. C., & MacColl, A. D. C. (2024). Reproductive isolation in a three‐way contact zone. Molecular Ecology, 33(5), Article e17275. https://doi.org/10.1111/mec.17275

Journal Article Type Article
Acceptance Date Jan 10, 2024
Online Publication Date Jan 18, 2024
Publication Date 2024-03
Deposit Date Jan 21, 2024
Publicly Available Date Jan 24, 2024
Journal Molecular Ecology
Print ISSN 0962-1083
Electronic ISSN 1365-294X
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 33
Issue 5
Article Number e17275
DOI https://doi.org/10.1111/mec.17275
Keywords introgression, hybrid, speciation, adaptation, contact zone, reproductive isolation
Public URL https://nottingham-repository.worktribe.com/output/29841321
Publisher URL https://onlinelibrary.wiley.com/doi/10.1111/mec.17275
Additional Information Received: 2023-09-19; Accepted: 2024-01-10; Published: 2024-01-18

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