Genetic response of a perennial grass to warm and wet environments interacts and is associated with trait means as well as plasticity

Potential for rapid evolution is an important mechanism allowing species to adapt to changing climatic conditions. Although such a potential has been largely studied in various short-lived organisms, to what extent we can observe similar patterns in long-lived plant species, which often dominate natural systems, is largely unexplored. We explored potential for rapid evolution in Festuca rubra, long-lived grass with extensive clonal growth dominating in alpine grasslands. We used field sowing experiment simulating expected climate change in our model region. Specifically, we exposed seeds from 5 independent seed sources to novel climatic conditions by shifting them along a natural climatic grid and explored genetic profiles of established seedling after 3 years. Data on genetic profiles of plants selected under different novel conditions indicate that different climate shifts select significantly different pools of genotypes from common seed pools. Increasing soil moisture was more important selective pressure than increasing temperature or interaction of the two climatic factors. This can indicate negative genetic interaction in response to the combined effects, or that the effects of different climates are interactive rather than additive. The selected alleles were found in genomic regions likely affecting function of specific genes or their expression. Many of these were also linked to morphological traits (mainly to trait plasticity) suggesting these changes may have a consequence for plant performance. Overall, these data indicate that even long-lived plant species may experience strong selection by climate, and their populations thus have the potential to rapidly adapt to these novel conditions.