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Fitness change in relation to mutation number in spontaneous mutation accumulation lines of Chlamydomonas reinhardtii
Author(s) -
Kraemer Susanne A.,
Böndel Katharina B.,
Ness Robert W.,
Keightley Peter D.,
Colegrave Nick
Publication year - 2017
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.13360
Subject(s) - biology , chlamydomonas reinhardtii , mutation accumulation , genetics , mutation , genetic fitness , genome , mutation rate , evolutionary biology , most recent common ancestor , gene , mutant
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.