Tolerance and potential for adaptation of a Baltic Sea rockweed under predicted climate change conditions

Abstract

<p>Climate change is threating species' persistence worldwide. To predict species responses to climate change we<br />need information not just on their environmental tolerance but also on its adaptive potential. We tested how the<br />foundation species of rocky littoral habitats, Fucus vesiculosus, responds to combined hyposalinity and warming<br />projected to the Baltic Sea by 2070–2099. We quantified responses of replicated populations originating from the<br />entrance, central, and marginal Baltic regions. Using replicated individuals, we tested for the presence of withinpopulation<br />tolerance variation. Future conditions hampered growth and survival of the central and marginal<br />populations whereas the entrance populations fared well. Further, both the among- and within-population<br />variation in responses to climate change indicated existence of genetic variation in tolerance. Such standing<br />genetic variation provides the raw material necessary for adaptation to a changing environment, which may<br />eventually ensure the persistence of the species in the inner Baltic Sea.<br /></p>