The Contribution of Spontaneous Mutation to Variation in Environmental Response in Arabidopsis Thaliana: Responses to Nutrients

Chang, Shu-Mei; Shaw, Ruth G.

doi:10.1111/j.0014-3820.2003.tb00310.x

Cited by 30 publications

(28 citation statements)

References 62 publications

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“…Attempts to relate mutational effects to environmental stress have produced inconsistent results (Kondrashov and Houle 1994;Fernández and Ló pez-Fanjul 1997;Shabalina et al 1997;Szafraniec et al 2001;Fry and Heinsohn 2002;Chang and Shaw 2003;Estes et al 2005;Kavanaugh and Shaw 2005). The importance of environmental effects is most closely associated with competitive fitness in Drosophila melanogaster (e.g., Shabalina et al 1997, but see Keightley et al 1998), although at least one study found no effect of competitive vs. noncompetitive conditions on the change in mean fitness (Fry and Heinsohn 2002).…”

Section: Resultsmentioning

confidence: 99%

Cumulative Effects of Spontaneous Mutations for Fitness in Caenorhabditis: Role of Genotype, Environment and Stress

et al. 2006

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It is often assumed that the mutation rate is an evolutionarily optimized property of a taxon. The relevant mutation rate is for mutations that affect fitness, U, but the strength of selection on the mutation rate depends on the average effect of a mutation. Determination of U is complicated by the possibility that mutational effects depend on the particular environmental context in which the organism exists. It has been suggested that the effects of deleterious mutations are typically magnified in stressful environments, but most studies confound genotype with environment, so it is unclear to what extent environmental specificity of mutations is specific to a particular starting genotype. We report a study designed to separate effects of species, genotype, and environment on the degradation of fitness resulting from new mutations. Mutations accumulated for .200 generations at 20°in two strains of two species of nematodes that differ in thermal sensitivity. Caenorhabditis briggsae and C. elegans have similar demography at 20°, but C. elegans suffers markedly reduced fitness at 25°. We find little evidence that mutational properties differ depending on environmental conditions and mutational correlations between environments are close to those expected if effects were identical in both environments.T HE importance of deleterious mutations to the evolutionary process is well appreciated (Morgan 1903;Haldane 1927;Fisher 1930;Sturtevant 1937;Kondrashov 1988), and much effort has been expended in understanding the processes by which new mutations arise and their effects on the phenotype and on fitness (reviewed by Simmons and Crow 1977;Drake et al. 1998;Keightley and Eyre-Walker 1999;Lynch et al. 1999;Houle and Kondrashov 2006). Drake, especially, has emphasized the remarkable consistency of the per-genome mutation rate across very broad taxonomic categories, but has also noted that there is considerable variation within those broad taxa (e.g., Drake et al. 1998). The idea that certain mutational properties vary between related species and even within species is venerable (Sturtevant 1937 and references therein), but there is as yet nothing approaching a comprehensive understanding of the variation in mutational properties-rate, distribution of effects, environmental sensitivity, molecular spectrum-of any species or group of closely related species, with the possible exception of the bacterium Escherichia coli (Matic et al. 1997;Sniegowski et al. 1997;Bjedov et al. 2003).An intriguing but almost completely unsubstantiated possibility (but see Nöthel 1987;Bjedov et al. 2003) is that mutation rates are themselves an evolutionarily optimized property (Fisher 1930;Sturtevant 1937;Kimura 1960Kimura , 1967Leigh 1970Leigh , 1973 Kondrashov 1995a,b;Dawson 1998). Because the vast majority of mutations with observable effects are deleterious, it is generally accepted that direct selection (almost) always favors a reduction in the mutation rate, with an optimal mutation rate of zero, at least in sexual taxa (e.g., Leig...

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Section: Resultsmentioning

confidence: 99%

Cumulative Effects of Spontaneous Mutations for Fitness in Caenorhabditis: Role of Genotype, Environment and Stress

et al. 2006

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“…In field experiments, the expectation is that more mutations will be involved in fitness, and they will have a greater effect on fitness. Stressful conditions are also known to increase the variance in mutations’ effects on fitness (Martin & Lenormand, 2006) and to result in mutations being more deleterious on average (Kondrashov & Houle, 1994 but see Chang & Shaw, 2003). For example, inbreeding depression is generally greater in more stressful versus less stressful environments (Dudash, 1990; Frankham, 2015; but see Waller, Dole, & Bersch, 2008; Agrawal & Whitlock, 2010).…”

Section: Introductionmentioning

confidence: 99%

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

Stearns

Fenster

2016

Ecology and Evolution

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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.

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“…Conversely, in Kishony and Leibler (2003), ⌬V is not given, so that we only report ⌬M. Finally, in two other studies of mutation effects across environments (Chang and Shaw 2003;Kavanaugh and Shaw 2005), there is no clear evidence of any fitness variance induced by mutation, in any environment, so we discarded these studies. As explained above, to estimate the effect of the environment on ⌬M and ⌬V we used log-ratio estimates of ⌬M (log[ M ]) and ⌬V (log[ V ]) in a given stressful environment relative to the estimate in the benign environment (denoted FIG.…”

Section: Survey Of Mutational Genotype-by-environmentmentioning

confidence: 98%

“…Since the work of Kondrashov and Houle (1994), several studies have documented differences in mutation effects across various environments for quantitative traits that are more or less related to fitness (reviewed in Lynch et al 1999;Fry and Heinsohn 2002;Lenormand 2002;Chang and Shaw 2003;Hermisson and Wagner 2004;Korona 2004). The im-plications of this environment dependence have been debated in an empirical and theoretical context.…”

mentioning

confidence: 99%

Untitled

2006

Evolution

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Abstract. The fitness effects of mutations on a given genotype are rarely constant across environments to which this genotype is more or less adapted, that is, between more or less stressful conditions. This can have important implications, especially on the evolution of ecological specialization. Stress is thought to increase the variance of mutations' fitness effects, their average, or the number of expressed mutations. Although empirical evidence is available for these three mechanisms, their relative magnitude is poorly understood. In this paper, we propose a simple approach to discriminate between these mechanisms, using a survey of empirical measures of mutation effects in contrasted environments. This survey, across various species and environments, shows that stress mainly increases the variance of mutations' effects on fitness, with a much more limited impact on their average effect or on the number of expressed mutations. This pattern is consistent with a simple model in which fitness is a Gaussian function of phenotypes around an environmentally determined optimum. These results suggest that a simple, mathematically tractable landscape model may not be quantitatively as unrealistic as previously suggested. They also suggest that mutation parameter estimates may be strongly biased when measured in stressful environments.

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The Contribution of Spontaneous Mutation to Variation in Environmental Response in Arabidopsis Thaliana: Responses to Nutrients

Cited by 30 publications

References 62 publications

Cumulative Effects of Spontaneous Mutations for Fitness in Caenorhabditis: Role of Genotype, Environment and Stress

Cumulative Effects of Spontaneous Mutations for Fitness in Caenorhabditis: Role of Genotype, Environment and Stress

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

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