Adaptive evolution of nontransitive fitness in yeast
A common misconception is that evolution is a linear 'march of progress', where each organism along a line of descent is more fit than all those that came before it. Rejecting this misconception implies that evolution is nontransitive: a series of adaptive events will, on occasion, produce organisms that are less fit compared to a distant ancestor. Here we identify a nontransitive evolutionary sequence in a 1,000-generation yeast evolution experiment. We show that nontransitivity arises due to adaptation in the yeast nuclear genome combined with the stepwise deterioration of an intracellular virus, which provides an advantage over viral competitors within host cells. Extending our analysis, we find that nearly half of our ~140 populations experience multilevel selection, fixing adaptive mutations in both the nuclear and viral genomes. Our results provide a mechanistic case-study for the adaptive evolution of nontransitivity due to multilevel selection in a 1,000-generation host/virus evolution experiment.
Illumina data of viral competitions and evolved nuclear genomes are accessible under the BioProject ID PRJNA553562 and PRJNA205542, respectively.
Article and author information
National Institutes of Health (R01GM127420)
- Gregory I Lang
Lehigh University (Faculty Innovation Grant)
- Gregory I Lang
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Wenying Shou, University College London, United Kingdom
- Received: August 18, 2020
- Accepted: December 25, 2020
- Accepted Manuscript published: December 29, 2020 (version 1)
- Version of Record published: February 16, 2021 (version 2)
© 2020, Buskirk et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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