University of Oulu

Olito, C., Ponnikas, S., Hansson, B., & Abbott, J. K. (2022). Consequences of partially recessive deleterious genetic variation for the evolution of inversions suppressing recombination between sex chromosomes. Evolution, 76(6), 1320–1330.

Consequences of partially recessive deleterious genetic variation for the evolution of inversions suppressing recombination between sex chromosomes

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Author: Olito, Colin1; Ponnikas, Suvi1,2; Hansson, Bengt1;
Organizations: 1Department of Biology, Lund University, Lund, 22362 Sweden
2Ecology and Genetics Research Unit, University of Oulu, Oulu, 90014 Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.1 MB)
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Language: English
Published: John Wiley & Sons, 2022
Publish Date: 2022-11-09


The evolution of suppressed recombination between sex chromosomes is widely hypothesized to be driven by sexually antagonistic selection (SA), where tighter linkage between the sex-determining gene(s) and nearby SA loci is favored when it couples male-beneficial alleles to the proto-Y chromosome, and female-beneficial alleles to the proto-X. Despite limited empirical evidence, the SA selection hypothesis overshadows several alternatives, including an incomplete but often-repeated “sheltering hypothesis” that suggests that expansion of the sex-linked region (SLR) reduces homozygous expression of partially recessive deleterious mutations at selected loci. Here, we use population genetic models to evaluate the consequences of deleterious mutational variation for the evolution of neutral chromosomal inversions expanding the SLR on proto-Y chromosomes. We find that SLR-expanding inversions face a race against time: lightly loaded inversions are initially beneficial, but eventually become deleterious as they accumulate new mutations, and must fix before this window of opportunity closes. The outcome of this race is strongly influenced by inversion size, the mutation rate, and the dominance coefficient of deleterious mutations. Yet, small inversions have elevated fixation probabilities relative to neutral expectations for biologically plausible parameter values. Our results demonstrate that deleterious genetic variation can plausibly drive recombination suppression in small steps and would be most consistent with empirical patterns of small evolutionary strata or gradual recombination arrest.

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Series: Evolution
ISSN: 0014-3820
ISSN-E: 1558-5646
ISSN-L: 0014-3820
Volume: 76
Issue: 6
Pages: 1320 - 1330
DOI: 10.1111/evo.14496
Type of Publication: B1 Journal article
Field of Science: 1184 Genetics, developmental biology, physiology
Funding: H2020 European Research Council. Grant Number: ERC-StG-2015-678148. Vetenskapsrådet. Grant Numbers: 621-2016-689, 2015-04680
Dataset Reference: Computer code needed to reproduce the simulations and main figures is available on GitHub ( and a version of record is archived on Zenodo (doi: 10.5281/zenodo.6361986).
Copyright information: © 2022 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.