This exercise is based on (Chano, Victor, Tania Dominguez-Flores, Maria Dolores Hidalgo- Galvez, Jesus Rodriguez-Calcerrada, and Ignacio Manuel Perez-Ramos. Epigenetic responses of hare barley (Hordeum murinum subsp. leporinum) to climate change: an experimental, trait-based approach. Heredity 126, no. 5 (2021): 748-762. What do they mean by combined stress factors may enhance phenotypic variation and plant fitness despite the presumably higher costs of plasticity? Why do you think phenotypic plasticity costly?.