--- _id: '5749' abstract: - lang: eng text: Parasitism creates selection for resistance mechanisms in host populations and is hypothesized to promote increased host evolvability. However, the influence of these traits on host evolution when parasites are no longer present is unclear. We used experimental evolution and whole-genome sequencing of Escherichia coli to determine the effects of past and present exposure to parasitic viruses (phages) on the spread of mutator alleles, resistance, and bacterial competitive fitness. We found that mutator alleles spread rapidly during adaptation to any of four different phage species, and this pattern was even more pronounced with multiple phages present simultaneously. However, hypermutability did not detectably accelerate adaptation in the absence of phages and recovery of fitness costs associated with resistance. Several lineages evolved phage resistance through elevated mucoidy, and during subsequent evolution in phage-free conditions they rapidly reverted to nonmucoid, phage-susceptible phenotypes. Genome sequencing revealed that this phenotypic reversion was achieved by additional genetic changes rather than by genotypic reversion of the initial resistance mutations. Insertion sequence (IS) elements played a key role in both the acquisition of resistance and adaptation in the absence of parasites; unlike single nucleotide polymorphisms, IS insertions were not more frequent in mutator lineages. Our results provide a genetic explanation for rapid reversion of mucoidy, a phenotype observed in other bacterial species including human pathogens. Moreover, this demonstrates that the types of genetic change underlying adaptation to fitness costs, and consequently the impact of evolvability mechanisms such as increased point-mutation rates, depend critically on the mechanism of resistance. acknowledgement: The authors thank three anonymous reviewers and the editor for helpful comments on the manuscript, as well as Dominique Schneider for feedback on an earlier draft, Jenna Gallie for lytic λ and Julien Capelle for T5 and T6. This work was supported by the Swiss National Science Foundation (PZ00P3_148255 to A.H.) and an EU Marie Curie PEOPLE Postdoctoral Fellowship for Career Development (FP7-PEOPLE-2012-IEF-331824 to S.W.). article_processing_charge: No author: - first_name: Sébastien full_name: Wielgoss, Sébastien last_name: Wielgoss - first_name: Tobias full_name: Bergmiller, Tobias id: 2C471CFA-F248-11E8-B48F-1D18A9856A87 last_name: Bergmiller orcid: 0000-0001-5396-4346 - first_name: Anna M. full_name: Bischofberger, Anna M. last_name: Bischofberger - first_name: Alex R. full_name: Hall, Alex R. last_name: Hall citation: ama: Wielgoss S, Bergmiller T, Bischofberger AM, Hall AR. Adaptation to parasites and costs of parasite resistance in mutator and nonmutator bacteria. Molecular Biology and Evolution. 2016;33(3):770-782. doi:10.1093/molbev/msv270 apa: Wielgoss, S., Bergmiller, T., Bischofberger, A. M., & Hall, A. R. (2016). Adaptation to parasites and costs of parasite resistance in mutator and nonmutator bacteria. Molecular Biology and Evolution. Oxford University Press. https://doi.org/10.1093/molbev/msv270 chicago: Wielgoss, Sébastien, Tobias Bergmiller, Anna M. Bischofberger, and Alex R. Hall. “Adaptation to Parasites and Costs of Parasite Resistance in Mutator and Nonmutator Bacteria.” Molecular Biology and Evolution. Oxford University Press, 2016. https://doi.org/10.1093/molbev/msv270. ieee: S. Wielgoss, T. Bergmiller, A. M. Bischofberger, and A. R. Hall, “Adaptation to parasites and costs of parasite resistance in mutator and nonmutator bacteria,” Molecular Biology and Evolution, vol. 33, no. 3. Oxford University Press, pp. 770–782, 2016. ista: Wielgoss S, Bergmiller T, Bischofberger AM, Hall AR. 2016. Adaptation to parasites and costs of parasite resistance in mutator and nonmutator bacteria. Molecular Biology and Evolution. 33(3), 770–782. mla: Wielgoss, Sébastien, et al. “Adaptation to Parasites and Costs of Parasite Resistance in Mutator and Nonmutator Bacteria.” Molecular Biology and Evolution, vol. 33, no. 3, Oxford University Press, 2016, pp. 770–82, doi:10.1093/molbev/msv270. short: S. Wielgoss, T. Bergmiller, A.M. Bischofberger, A.R. Hall, Molecular Biology and Evolution 33 (2016) 770–782. date_created: 2018-12-18T13:18:10Z date_published: 2016-03-01T00:00:00Z date_updated: 2023-09-05T13:46:05Z day: '01' ddc: - '576' department: - _id: CaGu doi: 10.1093/molbev/msv270 external_id: pmid: - '26609077' file: - access_level: open_access checksum: 47d9010690b6c5c17f2ac830cc63ac5c content_type: application/pdf creator: dernst date_created: 2018-12-18T13:21:45Z date_updated: 2020-07-14T12:47:10Z file_id: '5750' file_name: 2016_MolBiolEvol_Wielgoss.pdf file_size: 634037 relation: main_file file_date_updated: 2020-07-14T12:47:10Z has_accepted_license: '1' intvolume: ' 33' issue: '3' language: - iso: eng license: https://creativecommons.org/licenses/by-nc/4.0/ month: '03' oa: 1 oa_version: Published Version page: 770-782 pmid: 1 publication: Molecular Biology and Evolution publication_identifier: eissn: - 1537-1719 issn: - 0737-4038 publication_status: published publisher: Oxford University Press pubrep_id: '587' quality_controlled: '1' related_material: record: - id: '9719' relation: research_data status: public scopus_import: '1' status: public title: Adaptation to parasites and costs of parasite resistance in mutator and nonmutator bacteria tmp: image: /images/cc_by_nc.png legal_code_url: https://creativecommons.org/licenses/by-nc/4.0/legalcode name: Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) short: CC BY-NC (4.0) type: journal_article user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 33 year: '2016' ...