Fitness change in relation to mutation number in spontaneous mutation accumulation lines of Chlamydomonas reinhardtii |
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Authors: | Susanne A Kraemer Katharina B Böndel Robert W Ness Peter D Keightley Nick Colegrave |
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Institution: | 1. Institute of Evolutionary Biology, Ashworth Laboratories, University of Edinburgh, Edinburgh EH93FL, United Kingdom;2. Department of Biology, William G. Davis Building, University of Toronto, Mississuaga L5L1C6, Canada |
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Abstract: | Although all genetic variation ultimately stems from mutations, their properties are difficult to study directly. Here, we used multiple mutation accumulation (MA) lines derived from five genetic backgrounds of the green algae Chlamydomonas reinhardtii that have been previously subjected to whole genome sequencing to investigate the relationship between the number of spontaneous mutations and change in fitness from a nonevolved ancestor. MA lines were on average less fit than their ancestors and we detected a significantly negative correlation between the change in fitness and the total number of accumulated mutations in the genome. Likewise, the number of mutations located within coding regions significantly and negatively impacted MA line fitness. We used the fitness data to parameterize a maximum likelihood model to estimate discrete categories of mutational effects, and found that models containing one to two mutational effect categories (one neutral and one deleterious category) fitted the data best. However, the best‐fitting mutational effects models were highly dependent on the genetic background of the ancestral strain. |
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Keywords: | Chlamydomonas mutation accumulation mutational effects spontaneous mutations |
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