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Demographic fluctuations and selection during host-parasite coevolution interactively increase genetic diversity
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  • Guénolé Le Pennec,
  • Cas Retel,
  • Vienna Kowallik,
  • Lutz Becks,
  • Philine Feulner
Guénolé Le Pennec
Eawag, Swiss Federal Institute of Aquatic Science and Technology

Corresponding Author:[email protected]

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Cas Retel
Eawag, Swiss Federal Institute of Aquatic Science and Technology
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Vienna Kowallik
University of Freiburg Faculty of Forestry and Environmental Sciences
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Lutz Becks
University of Konstanz
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Philine Feulner
Eawag, Swiss Federal Institute of Aquatic Science and Technology
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Host-parasite interactions can cause strong demographic fluctuations accompanied by selective sweeps of resistance/infectivity alleles. Both demographic bottlenecks and frequent sweeps are expected to reduce the amount of segregating genetic variation and therefore might constrain adaption during coevolution. Recent studies, however, suggest that the interaction of demographic and selective processes is a key component of coevolutionary dynamics and may rather positively affect levels of genetic diversity available for adaptation. Here, we provide direct experimental testing of this hypothesis by disentangling the effect of demography, selection, and of their interaction in an experimental host-parasite system. We grew 12 populations of unicellular algae (Chlorella variabilis) that experienced either growth followed by constant population sizes (3 populations), demographic fluctuations (3 populations), selection induced by exposure to a virus (3 populations), or demographic fluctuations together with virus-induced selection (3 populations). After 50 days, we conducted whole-genome sequencing of each algal population. We observed more genetic diversity in populations that jointly experienced selection and demographic fluctuations than in populations where these processes were experimentally separated. In addition, in those 3 populations that jointly experienced selection and demographic fluctuations, experimentally measured diversity exceeds expected values of diversity that account for the cultures’ population sizes. Our results suggest that eco-evolutionary feedbacks can positively affect genetic diversity and provide the necessary empirical measures to guide further improvements of theoretical models of adaptation during host-parasite coevolution.
27 Oct 2022Submitted to Molecular Ecology
01 Nov 2022Submission Checks Completed
01 Nov 2022Assigned to Editor
01 Nov 2022Review(s) Completed, Editorial Evaluation Pending
10 Nov 2022Reviewer(s) Assigned
16 Jan 2023Editorial Decision: Revise Minor
17 Mar 20231st Revision Received
20 Mar 2023Submission Checks Completed
20 Mar 2023Assigned to Editor
20 Mar 2023Review(s) Completed, Editorial Evaluation Pending
22 Mar 2023Editorial Decision: Accept