No abstract

Plant populations must continuously adapt to the impacts of ongoing global climate change, including warmer temperatures and more extreme weather events. We can detect such evolutionary changes within plant populations through the resurrection approach whereby plants grown from seeds stored in seed banks (“ancestors”) are compared to freshly collected seeds from the same populations (“descendants”) in common garden experiments. In this study we used the resurrection approach in two multi-species experiments to investigate changes in phenotypic traits and drought tolerance of European plant species from two biogeographic regions. In the seedling survival experiment using seedlings of four Mediterranean species, watering was ceased and day of mortality recorded. We found that descendants survived significantly longer without any watering but these seedlings were smaller than the ancestral seedlings. In the watering response experiment we investigated phenotypic responses to drought in adult plants of nine species originating from temperate climatic regions in Europe. We found that descendant plants were significantly taller under well-watered conditions but smaller under drought than their ancestors, thus showing stronger plasticity. Our study suggests that plants have already evolved phenotypically, including through changes in trait means and plasticity, within the last decades. The observed evolutionary changes are consistent with adaptation to increased drought. More generally, the resurrection approach proved to be a useful tool to study rapid evolutionary processes in plants under climate change. Future studies should include fitness measures and comparative transplantations of descendants and ancestors into their original habitat to disentangle adaptive from non-adaptive responses to recent climate change.