Comparative linkage mapping uncovers recombination suppression across massive chromosomal inversions associated with local adaptation in Atlantic silversides

Akopyan, M., Tigano, A., Jacobs, A. , Wilder, A. P., Baumann, H. and Therkildsen, N. O. (2022) Comparative linkage mapping uncovers recombination suppression across massive chromosomal inversions associated with local adaptation in Atlantic silversides. Molecular Ecology, (doi: 10.1111/mec.16472) (Early Online Publication)

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The role of recombination in genome evolution has long been studied in theory, but until recently empirical investigations had been limited to a small number of model species. Here we compare the recombination landscape and genome collinearity between two populations of the Atlantic silverside (Menidia menidia), a small fish distributed across the steep latitudinal climate gradient of the North American Atlantic coast. We constructed separate linkage maps for locally adapted populations from New York and Georgia and their inter-population lab cross. First, we used one of the linkage maps to improve the current silverside genome assembly by anchoring three large unplaced scaffolds to two chromosomes. Second, we estimated sex-specific recombination rates, finding 2.3-fold higher recombination rates in females than males—one of the most extreme examples of heterochiasmy in a fish. While recombination occurs relatively evenly across female chromosomes, it is restricted to only the terminal ends of male chromosomes. Furthermore, comparisons of female linkage maps revealed suppressed recombination along several massive chromosomal inversions spanning nearly 16% of the genome. These inversions segregate between locally adapted populations and coincide near perfectly with blocks of highly elevated genomic differentiation between wild populations. Finally, we discerned significantly higher recombination rates across chromosomes in the northern population compared to the southern. In addition to providing valuable resources for ongoing evolutionary and comparative genomic studies, our findings represent a striking example of structural variation that impacts recombination between adaptively divergent populations, providing empirical support for theorized genomic mechanisms facilitating adaptation despite gene flow.

Item Type:Articles
Additional Information:This study was funded through a National Science Foundation grant to NOT (OCE‐1756316) and OCE-1756751 to HB.
Status:Early Online Publication
Glasgow Author(s) Enlighten ID:Jacobs, Mr Arne
Authors: Akopyan, M., Tigano, A., Jacobs, A., Wilder, A. P., Baumann, H., and Therkildsen, N. O.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Molecular Ecology
ISSN (Online):1365-294X
Published Online:11 April 2022
Copyright Holders:Copyright © 2022
First Published:First published in Molecular Ecology 2022
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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