The contemporary evolution of organisms is largely dependent on anthropogenic disturbances. In particular, the pollution amplifies the intensity or the quantity of selection pressures suffered by populations. However, these changes may have negative effects on the life of individuals, the demographics of the populations, and its phenotypic and genetic characteristics over generations. Thus, microevolutionary changes are likely to occur in response to selection pressures. These phenomenon lead to collateral damages: adaptive costs. Populations can be more susceptible to many environmental changes. Hence, it is essential to expand our knowledge on the evolution of populations in polluted environment. In this context, our study aims to determine the microevolutionary response of C. elegans
populations exposed to different pollutions, and to measure their costs of adaptation. Populations were experimentally exposed for 22 generations to a high concentration of uranium or sodium chloride. We confirmed the genetic differentiation between populations with an increase of resistance in populations exposed to different pollutions. The speed of evolutionary responses depended on exposure conditions and their effects on the expression of the genetic structure of life history traits. Microevolutionary changes were linked to costs of adaptation, such as reduced fertility, in stressful novel environments (e.g. fast temperature raise) or in the absence of stress. This project allowed us to better identify how exposure to one or two pollutants affects the evolutionary response of C. elegans
populations and evaluate the impact on their sensitivity to environmental conditions.