The question of evolutionary processes in ecotoxicology becomes substantial in order to propose relevant ecological risk assessment. Actually, it is well admitted that pollutants can be strong selective agents which can induced adaptation in exposed populations. Our study analyses two possible ways of adaptation: first, the evolution of resistance and second, the evolution of life-history patterns. This second point is rarely tackled in ecotoxicological issues, contrary to other fields of ecology dealing with stress adaptation. To answer these questions we adopted a retrospective approach based on the comparison of sensitivities and traits of exposed and unexposed field populations. To provide representative results, the choice has been made to work on an ecologically and ecotoxicologically relevant species, the freshwater amphipod, Gammarus fossarum. Particular attention was also paid to the design of the study through the sampling effort with the selection of nine field populations spread out at a regional scale. The exposition of organisms from these populations to cadmium, and the measure of their life-history traits in the field and in common garden in the lab, show that organisms are not only able to respond to pollutants by increased tolerance, but also by life-history adaptation. Nevertheless, our results also demonstrate that adaptation is not automatic and seems to depend on contamination strength. In addition, these phenomenon are probably not out of unexpected outcomes since they can induced fitness costs, and changes in population dynamics can affect higher ecological scales.