Abstract
Classical mutational theories centered on single nucleotide polymorphisms suggest that outcrossing enhances the purging of deleterious mutations by promoting recombination. However, larger structural variants, such as insertions, deletions, and inversions, can suppress recombination and create linkage blocks. Using experimental evolution and whole-genome long- and short-read sequencing, we characterized structural and nucleotide mutation landscapes in three Caenorhabditis elegans strains following repeated mutagen exposure and recovery. We found substantial strain-specific differences in structural variant accumulation and mutation retention. The strain with the highest outcrossing propensity exhibited the greatest structural variant burden and a higher fraction of single nucleotide polymorphisms within structural variant intervals. Consistent with this pattern, our population genetic simulations showed that structural variants can persist more readily under higher outcrossing rates. Together, these results indicate that structural variant architecture may influence mutation retention dynamics and highlight strain-specific constraints on purging following mutagenesis in C. elegans.
Acknowledgements
The authors would like to thank the members of the Fierst lab and Jessica Gonzalez, Jason Pienaar, and Jesualdo Fuentes-Gonzalez for suggestions and careful feedback. We also thank four anonymous reviewers who provided thorough review and greatly improved the work.
Funding
This work was supported by NSF award 2225796 and NIGMS award R35GM147245 to J.L.F.
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Kapila, R., Saber, S., Verma, R.K. et al. Strain-specific structural variant landscapes shape mutation retention following mutagenesis in Caenorhabditis elegans. Commun Biol (2026). https://doi.org/10.1038/s42003-026-10910-9
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DOI: https://doi.org/10.1038/s42003-026-10910-9