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Fitness effects of new mutations in Chlamydomonas reinhardtii across two stress gradients
Author(s) -
Kraemer S. A.,
Morgan A. D.,
Ness R. W.,
Keightley P. D.,
Colegrave N.
Publication year - 2016
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/jeb.12807
Subject(s) - biology , chlamydomonas reinhardtii , selection (genetic algorithm) , genetic fitness , genetic load , evolutionary biology , genetics , chlamydomonas , genetic variation , mutation , population , stress (linguistics) , gene , demography , artificial intelligence , sociology , mutant , computer science , inbreeding , linguistics , philosophy
Most spontaneous mutations affecting fitness are likely to be deleterious, but the strength of selection acting on them might be impacted by environmental stress. Such stress‐dependent selection could expose hidden genetic variation, which in turn might increase the adaptive potential of stressed populations. On the other hand, this variation might represent a genetic load and thus lead to population extinction under stress. Previous studies to determine the link between stress and mutational effects on fitness, however, have produced inconsistent results. Here, we determined the net change in fitness in 29 genotypes of the green algae Chlamydomonas reinhardtii that accumulated mutations in the near absence of selection for approximately 1000 generations across two stress gradients, increasing NaCl and decreasing phosphate. We found mutational effects to be magnified under extremely stressful conditions, but such effects were specific both to the type of stress and to the genetic background. The detection of stress‐dependent fitness effects of mutations depended on accurately scaling relative fitness measures by generation times, thus offering an explanation for the inconsistencies among previous studies.