Genomic Mutation in Lines of Arabidopsis thaliana Exposed to Ultraviolet-B Radiation

2018

Mutations create novel genetic variants, but their contribution to variation in fitness and other phenotypes may depend on environmental conditions. Furthermore, natural environments may be highly heterogeneous. We assessed phenotypes associated with survival and reproductive success in over 30,000 plants representing 100 mutation accumulation lines of Arabidopsis thaliana across four temporal environments at a single field site. In each of the four assays, environmental variance was substantially larger than mutational variance. For some traits, whether mutational variance was significantly varied between seasons. The founder genotype had mean trait values near the mean of the distribution of the mutation accumulation lines in all field experiments. New mutations also contributed more phenotypic variation than would be predicted, given phenotypic and sequence‐level divergence among natural populations of A. thaliana. The combination of large environmental variance with a mean effect of mutation near zero suggests that mutations could contribute substantially to standing genetic variation.

Section: Discussionmentioning

confidence: 99%

Quantifying natural seasonal variation in mutation parameters with mutation accumulation lines

Rutter

Roles

2018

“…Significant mutant line effects suggest that measured differences in these traits were due to induced mutations. These results are consistent with the notion that most mutations are deleterious (Keightley & Lynch, 2003) but conflict with recent results in studies of A. thaliana mutant lines (MacKenzie et al., 2005; Rutter et al., 2010; Shaw et al., 2000). …”

Section: Discussionmentioning

confidence: 99%

“…Earlier work on A. thaliana mutation accumulation lines, as well as on mutation accumulation lines from other species, has demonstrated that mutations can be beneficial more often than previously believed (Hall & Joseph, 2010; MacKenzie et al., 2005; Rutter et al., 2010; Shaw et al., 2000). In A. thaliana , mutation accumulation lines have been shown to have increased fitness over the premutation founder as much as 1/3 to 1/2 the time (MacKenzie et al., 2005; Rutter et al., 2010; Shaw et al., 2000), corresponding to high beneficial mutation rates.…”

Section: Discussionmentioning

confidence: 99%

“…In A. thaliana , mutation accumulation lines have been shown to have increased fitness over the premutation founder as much as 1/3 to 1/2 the time (MacKenzie et al., 2005; Rutter et al., 2010; Shaw et al., 2000), corresponding to high beneficial mutation rates. However, here we found that most mutant lines (19/20) had reduced fitness relative to the premutation founder under field conditions.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, mutant lines in A. thaliana were found to increase fitness components relative to a premutated founder nearly half the time under both greenhouse (MacKenzie et al., 2005; Shaw et al., 2000) and field conditions (Rutter et al., 2010). This suggests that new mutations may be able to contribute to adaptation more quickly than previously assumed, although more study is needed before we can unequivocally state that beneficial mutations occur at high frequency.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The effect of induced mutations on quantitative traits in Arabidopsis thaliana: Natural versus artificial conditions

Stearns

2016

Mutations are the ultimate source of all genetic variations. New mutations are expected to affect quantitative traits differently depending on the extent to which traits contribute to fitness and the environment in which they are tested. The dogma is that the preponderance of mutations affecting fitness will be skewed toward deleterious while their effects on nonfitness traits will be bidirectionally distributed. There are mixed views on the role of stress in modulating these effects. We quantify mutation effects by inducing mutations in Arabidopsis thaliana (Columbia accession) using the chemical ethylmethane sulfonate. We measured the effects of new mutations relative to a premutation founder for fitness components under both natural (field) and artificial (growth room) conditions. Additionally, we measured three other quantitative traits, not expected to contribute directly to fitness, under artificial conditions. We found that induced mutations were equally as likely to increase as decrease a trait when that trait was not closely related to fitness (traits that were neither survivorship nor reproduction). We also found that new mutations were more likely to decrease fitness or fitness‐related traits under more stressful field conditions than under relatively benign artificial conditions. In the benign condition, the effect of new mutations on fitness components was similar to traits not as closely related to fitness. These results highlight the importance of measuring the effects of new mutations on fitness and other traits under a range of conditions.

Evidence for parallel adaptation to climate across the natural range of Arabidopsis thaliana

Stearns

2013

How organisms adapt to different climate habitats is a key question in evolutionary ecology and biological conservation. Species distributions are often determined by climate suitability. Consequently, the anthropogenic impact on earth's climate is of key concern to conservation efforts because of our relatively poor understanding of the ability of populations to track and evolve to climate change. Here, we investigate the ability of Arabidopsis thaliana to occupy climate space by quantifying the extent to which different climate regimes are accessible to different A. thaliana genotypes using publicly available data from a large-scale genotyping project and from a worldwide climate database. The genetic distance calculated from 149 single-nucleotide polymorphisms (SNPs) among 60 lineages of A. thaliana was compared to the corresponding climate distance among collection localities calculated from nine different climatic factors. A. thaliana was found to be highly labile when adapting to novel climate space, suggesting that populations may experience few constraints when adapting to changing climates. Our results also provide evidence of a parallel or convergent evolution on the molecular level supporting recent generalizations regarding the genetics of adaptation.