It is often assumed that the ability of plants to acclimatize to the local environment through non-genetic changes in their anatomy and physiology (phenotypic plasticity) is important for the success of invasive species. In this study, Marchini et al. describe a case where traits of an invasive grass, the perennial bunchgrass Brachypodium sylvaticum (Poaceae) associated with drought tolerance are strongly canalized, and do not display plasticity in response to soil water availability.
Instead, the success of this aggressively invasive species appears to be due to rapid genetic differentiation and adaptation to novel climatic conditions in its introduced range in the Pacific Northwest region of North America. Canalization of leaf anatomical and physiological traits associated with drought tolerance is likely to be due to the fact that the leaves of this perennial bunchgrass develop early in the spring when conditions are cool and moist; the same leaves are maintained through the late summer when they are exposed to extreme drought and high temperatures. Photo by Alisa Ramakrishnan.