A field study of the molecular response of brown macroalgae to heavy metal exposure: an (epi) genetic approach

In previous studies, we found differences in heavy metal uptake capacity between populations of the brown macroalga Fucus vesiculosus. This suggested that algae from different populations may have adapted to contamination by these toxic elements. The next logical step was to assess which molecular mechanisms were responsible for these differences: genetic differentiation (variations in the nucleotide sequence of DNA that determine differences in its functioning) or epigenetic differentiation (variations in the chemical marks of the DNA molecule that also determine differences in its functioning independently of nucleotide sequences). We trasplanted algae from contaminated to uncontaminated areas and vice versa, kept them for 90 days, and analysed genetic and epigenetic variability before and after the experiment. Our results showed genetic differences between the four populations studied, although these did not explain the differences in metal uptake capacity. However, we observed epigenetic changes in the different populations in response to changes in environmental conditions (i.e. transplantation away from the site of origin). We propose that both genetic and, to some extent, epigenetic mechanisms may play a role in the adaptive potential of this species to environmental change, but further studies are needed.