Biomarkers can reect the actual state of health of organisms or populations, but do not provide information on the potential of a population to survive in a polluted environment. Genetic approaches can, however, produce relevant knowledge in an ecotoxicology study. Indeed, the genetic variation in populations results from their evolutionary histories and represents the raw material that has, or has not, enabled the evolutionary adaptation of these populations faced with environmental challenges (global change, hypoxia, emerging contaminants, multistress, etc.).