Additive genetic variation for tolerance to estrogen pollution in natural populations of A lpine whitefish ( C oregonus sp., S almonidae)

The evolutionary potential of natural populations to adapt to anthropogenic threats critically depends on whether there exists additive genetic variation for tolerance to the threat. A major problem for water‐dwelling organisms is chemical pollution, and among the most common pollutants is 17 α ‐ethinylestradiol ( EE 2), the synthetic estrogen that is used in oral contraceptives and that can affect fish at various developmental stages, including embryogenesis. We tested whether there is variation in the tolerance to EE 2 within A lpine whitefish. We sampled spawners from two species of different lakes, bred them in vitro in a full‐factorial design each, and studied growth and mortality of embryos. Exposure to EE 2 turned out to be toxic in all concentrations we tested (≥1 ng/L). It reduced embryo viability and slowed down embryogenesis. We found significant additive genetic variation in EE 2‐induced mortality in both species, that is, genotypes differed in their tolerance to estrogen pollution. We also found maternal effects on embryo development to be influenced by EE 2, that is, some maternal sib groups were more susceptible to EE 2 than others. In conclusion, the toxic effects of EE 2 were strong, but both species demonstrated the kind of additive genetic variation that is necessary for an evolutionary response to this type of pollution.