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Pollution Breaks Down the Genetic Architecture of Life History Traits in Caenorhabditis elegans

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ABSTRACT

When pollution occurs in an environment, populations present suffer numerous negative and immediate effects on their life history traits. Their evolutionary potential to live in a highly stressful environment will depend on the selection pressure strengths and on the genetic structure, the trait heritability, and the genetic correlations between them. If expression of this structure changes in a stressful environment, it becomes necessary to quantify these changes to estimate the evolutionary potential of the population in this new environment. We studied the genetic structure for survival, fecundity, and early and late growth in isogenic lines of a Caenorhabditis elegans population subject to three different environments: a control environment, an environment polluted with uranium, and a high salt concentration environment. We found a heritability decrease in the polluted environments for fecundity and early growth, two traits that were the most heritable in the control environment. The genetic structure of the traits was particularly affected in the uranium polluted environment, probably due to generally low heritability in this environment. This could prevent selection from acting on traits despite the strong selection pressures exerted on them. Moreover, phenotypic traits were more strongly affected in the salt than in the uranium environment and the heritabilities were also lower in the latter environment. Consequently the decrease in heritability was not proportional to the population fitness reduction in the polluted environments. Our results suggest that pollution can alter the genetic structure of a C. elegans population, and thus modify its evolutionary potential.

No MeSH data available.


Trait variance estimates forC. elegansin the different environments.Variances are presented with their 95% intervals of Bayesian credibility. (A) fecundity and (B) early growth. Phenotypic variance (VP) is split into environmental (VE) and genetic variances (VG). Estimates were obtained using multivariate models for different traits within the same environment.
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pone.0116214.g001: Trait variance estimates forC. elegansin the different environments.Variances are presented with their 95% intervals of Bayesian credibility. (A) fecundity and (B) early growth. Phenotypic variance (VP) is split into environmental (VE) and genetic variances (VG). Estimates were obtained using multivariate models for different traits within the same environment.

Mentions: Heritability estimates varied between 0.07 and 0.31 in the control environment and were only significantly higher than zero for fecundity and early growth (Table 2). In the uranium environment, we found lower (i.e. 0.04 to 0.08) and non-significant heritabilities (Table 3). In the salt environment, heritability values varied between 0.07 and 0.27, but were only significant for early growth (Table 4). Heritability did not differ significantly between the control and the salt environments for fecundity and early growth, but heritability in the control environment was significantly higher than in the uranium environment (95% HPDIs after subtraction did not include zero). Phenotypic variance for these two traits declined in both the polluted environments compared to the control. However, in the uranium environment there was a larger reduction in genetic variance than in environmental variance, compared to the control (95% HPDIs after subtraction did not include zero, see Fig. 1 for fecundity and early growth and see S2 Fig. for information on late growth), which was directly related to lower heritabilities in this polluted environment (Table 2 and Table 3). Phenotypic variance for fecundity was twice as high in the control environment (Vp = 0.114 [0.083; 0.180]) than in the salt environment (Vp = 0.059 [0.042; 0.086]) and three times higher than in the uranium environment (Vp = 0.040 [0.034; 0.054] (see Fig. 1A and S3 Fig. for representations of phenotypic correlation structures). The difference was less pronounced for early growth but was still significantly different (Fig. 1B).


Pollution Breaks Down the Genetic Architecture of Life History Traits in Caenorhabditis elegans
Trait variance estimates forC. elegansin the different environments.Variances are presented with their 95% intervals of Bayesian credibility. (A) fecundity and (B) early growth. Phenotypic variance (VP) is split into environmental (VE) and genetic variances (VG). Estimates were obtained using multivariate models for different traits within the same environment.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4340920&req=5

pone.0116214.g001: Trait variance estimates forC. elegansin the different environments.Variances are presented with their 95% intervals of Bayesian credibility. (A) fecundity and (B) early growth. Phenotypic variance (VP) is split into environmental (VE) and genetic variances (VG). Estimates were obtained using multivariate models for different traits within the same environment.
Mentions: Heritability estimates varied between 0.07 and 0.31 in the control environment and were only significantly higher than zero for fecundity and early growth (Table 2). In the uranium environment, we found lower (i.e. 0.04 to 0.08) and non-significant heritabilities (Table 3). In the salt environment, heritability values varied between 0.07 and 0.27, but were only significant for early growth (Table 4). Heritability did not differ significantly between the control and the salt environments for fecundity and early growth, but heritability in the control environment was significantly higher than in the uranium environment (95% HPDIs after subtraction did not include zero). Phenotypic variance for these two traits declined in both the polluted environments compared to the control. However, in the uranium environment there was a larger reduction in genetic variance than in environmental variance, compared to the control (95% HPDIs after subtraction did not include zero, see Fig. 1 for fecundity and early growth and see S2 Fig. for information on late growth), which was directly related to lower heritabilities in this polluted environment (Table 2 and Table 3). Phenotypic variance for fecundity was twice as high in the control environment (Vp = 0.114 [0.083; 0.180]) than in the salt environment (Vp = 0.059 [0.042; 0.086]) and three times higher than in the uranium environment (Vp = 0.040 [0.034; 0.054] (see Fig. 1A and S3 Fig. for representations of phenotypic correlation structures). The difference was less pronounced for early growth but was still significantly different (Fig. 1B).

View Article: PubMed Central - PubMed

ABSTRACT

When pollution occurs in an environment, populations present suffer numerous negative and immediate effects on their life history traits. Their evolutionary potential to live in a highly stressful environment will depend on the selection pressure strengths and on the genetic structure, the trait heritability, and the genetic correlations between them. If expression of this structure changes in a stressful environment, it becomes necessary to quantify these changes to estimate the evolutionary potential of the population in this new environment. We studied the genetic structure for survival, fecundity, and early and late growth in isogenic lines of a Caenorhabditis elegans population subject to three different environments: a control environment, an environment polluted with uranium, and a high salt concentration environment. We found a heritability decrease in the polluted environments for fecundity and early growth, two traits that were the most heritable in the control environment. The genetic structure of the traits was particularly affected in the uranium polluted environment, probably due to generally low heritability in this environment. This could prevent selection from acting on traits despite the strong selection pressures exerted on them. Moreover, phenotypic traits were more strongly affected in the salt than in the uranium environment and the heritabilities were also lower in the latter environment. Consequently the decrease in heritability was not proportional to the population fitness reduction in the polluted environments. Our results suggest that pollution can alter the genetic structure of a C. elegans population, and thus modify its evolutionary potential.

No MeSH data available.