The limit to evolutionary rescue depends on ploidy in yeast exposed to nystatin

Ono, Jasmine; Kuzmin, Anastasia; Miller, Lesley; Otto, Sarah P.

Abstract

The number of copies of each chromosome, or ploidy, of an organism is a major genomic factor affecting adaptation. We set out to determine how ploidy can impact the outcome of evolution, as well as the likelihood of evolutionary rescue, using short-term experiments with yeast (Saccharomyces cerevisiae) in a high concentration of the fungicide nystatin. In similar experiments using haploid yeast, the genetic changes underlying evolutionary rescue were highly repeatable, with all rescued lines containing a single mutation in the ergosterol biosynthetic pathway. All of these beneficial mutations were recessive, which led to the expectation that diploids would find alternative genetic routes to adaptation. To test this, we repeated the experiment using both haploid and diploid strains and found that diploid populations did not evolve resistance. Although diploids are able to adapt at the same rate as haploids to a lower, not fully inhibitory, concentration of nystatin, the present study suggests that diploids are limited in their ability to adapt to an inhibitory concentration of nystatin, while haploids may undergo evolutionary rescue. These results demonstrate that ploidy can tip the balance between adaptation and extinction when organisms face an extreme environmental change.

Citation

Ono, J., Kuzmin, A., Miller, L., & Otto, S. P. (2024). The limit to evolutionary rescue depends on ploidy in yeast exposed to nystatin. Canadian Journal of Microbiology, 70(9), 394-404. https://doi.org/10.1139/cjm-2023-0235

• Journal Article Type: Article
• Acceptance Date: May 13, 2024
• Online Publication Date: Jul 31, 2024
• Publication Date: Sep 1, 2024
• Deposit Date: Aug 8, 2024
• Publicly Available Date: Aug 9, 2024
• Journal: Canadian Journal of Microbiology
• Print ISSN: 0008-4166
• Electronic ISSN: 1480-3275
• Publisher: NRC Research Press
• Peer Reviewed: Peer Reviewed
• Volume: 70
• Issue: 9
• Pages: 394-404
• DOI: https://doi.org/10.1139/cjm-2023-0235
• Keywords: evolutionary rescue, adaptation, ploidy, yeast, Saccharomyces cerevisiae, experimental evolution
• Public URL: https://nottingham-repository.worktribe.com/output/38114190
• Publisher URL: https://cdnsciencepub.com/doi/10.1139/cjm-2023-0235
• Additional Information: Data generated and analyzed during this study, as well as the scripts used for analysis, are available in the Zenodo repository (doi:10.5281/zenodo.10947969, https://zenodo.org/records/10947970) and the National Center for Biotechnology Information Sequence Read Archive (accession No. PRJNA1112093, https://www.ncbi.nlm.nih.gov/bioproject/PRJNA1112093).