Knowledge of the ability of plants to respond to climate change via phenotypic plasticity or genetic adaptation in ecophysiological traits and of the link of these traits to fitness is still limited. We studied the clonal grass Festuca rubra from 11 localities representing factorially crossed gradients of temperature and precipitation and cultivated them in growth chambers simulating temperature and moisture regime in the

9Background: Understanding the ability of species to respond to climate change is essential for 10 prediction of their future distribution. When migration is not adequate, reaction via phenotypic plasticity 11 or genetic adaptation is necessary. While many studies investigated the importance of plasticity and 12 genetic differentiation (plant origin) in growth related traits, we know less about differentiation in 13 ecophysiological traits. In addition, the existing studies looking at plant physiology usually do not 14 estimate the consequences of these physiological changes for species performance. 15 Methods:We used a clonal grass Festuca rubra originating from localities representing factorially 16 crossed gradients of temperatures and precipitations. We cultivated the plants in growth chambers set 17 to simulate temperature and moisture regime in the four most extreme localities. We measured net 18 photosynthetic rate, chlorophyll fluorescence, SLA, osmotic potential, stomatal density and stomatal 19 length as range of ecophysiological traits and tested their relationship to plant fitness measured as ramet 20 number and biomass. 21Key results: We found strong phenotypic plasticity in photosynthetic traits and genetic differentiation 22 in stomatal traits. In most traits, the effects of temperature interacted with the effects of moisture. The 23 relationship between the ecophysiological and fitness-related traits was significant but weak. 24Conclusions: Ecophysiological response of Festuca rubra to climate change is driven by phenotypic 25 plasticity as well as by genetic differentiation indicating potential ability of the populations to adapt to 26 new climatic conditions. The changes in ecophysiological traits translate into plant fitness even though 27 other unmeasured factors also play an important role in fitness determination. Inclusion of species 28 ecophysiology into studies of species adaptation to climate can still increase our ability to understand 29 how species may respond to novel conditions. 30 31

Knowledge of the relationship between environmental conditions and species traits is an important prerequisite for understanding determinants of community composition and predicting species response to novel climatic conditions. Despite increasing number of studies on this topic, our knowledge on importance of genetic differentiation, plasticity and their interactions along larger sets of species is still limited especially for traits related to plant ecophysiology. We studied variation in traits related to growth, leaf chemistry, contents of photosynthetic pigments and activity of antioxidative enzymes, stomata morphology and photosynthetic activity across eight Impatiens species growing along altitudinal gradients in Himalayas cultivated in three different temperature regimes and explored effects of among species phylogenetic relationships on the results. Original and target climatic conditions determine trait values in our system. The traits are either highly plastic (e.g., APX, CAT, plant size, neoxanthin, β-carotene, chlorophyll a/b, DEPSC) or are highly differentiated among populations (stomata density, lutein production). Many traits show strong among population differentiation in degree of plasticity and direction in response to environmental changes. Most traits indicate that the species will profit from the expected warming. This suggests that different processes determine the values of the different traits and separating the importance of genetic differentiation and plasticity is crucial for our ability to predict species response to future climate changes. The results also indicate that evolution of the traits is not phylogenetically constrained but including phylogenetic information into the analysis may improve our understanding of the trait-environment relationships as was apparent from the analysis of SLA.

Epigenetic regulation of gene expression is expected to be an important mechanism behind phenotypic plasticity. Whether epigenetic regulation affects species ecophysiological adaptations to changing climate remains largely unexplored. We compared ecophysiological traits between individuals treated with 5-azaC, assumed to lead to DNA demethylation, with control individuals of a clonal grass originating from and grown under different climates, simulating different directions and magnitudes of climate change. We linked the ecophysiological data to proxies of fitness. Main effects of plant origin and cultivating conditions predicted variation in plant traits, but 5-azaC did not. Effects of 5-azaC interacted with conditions of cultivation and plant origin. The direction of the 5-azaC effects suggests that DNA methylation does not reflect species long-term adaptations to climate of origin and species likely epigenetically adjusted to the conditions experienced during experiment set-up. Ecophysiology translated to proxies of fitness, but the intensity and direction of the relationships were context dependent and affected by 5-azaC. The study suggests that effects of DNA methylation depend on conditions of plant origin and current climate. Direction of 5-azaC effects suggests limited role of epigenetic modifications in long-term adaptation of plants. It rather facilitates fast adaptations to temporal fluctuations of the environment.