Gender-specific variation in physiology in the dioecious shrub Corema album throughout its distributional range

Different requirements for reproduction between sexes in dioecious plants can lead to gender-specific physiological responses to environmental constraints. Females generally endure higher reproductive investment and costs than males, displaying lower water and nutrient use efficiency and growth. We studied the ecophysiology of the dioecious shrub Corema album L. (D.) Don. to assess how drought impacts physiological responses and gender dimorphism along an aridity gradient within the species' range. Leaf gas exchange, photochemical efficiency (F-v/F-m), water potential (Psi), vegetative growth (VG) and leaf C isotopic discrimination and nitrogen content were measured in three populations under markedly different climatic conditions. Physiological responses and growth indicated higher level of stress in the drier environments, leading to increased WUE (Delta) and lower VG. Physiological stress increases among plants were related to incremental changes in the degree of gender dimorphism, with significant effects on Psi and F-v/F-m (P < 0.05); males showed higher VG (P < 0.001). Multivariate analysis of instantaneous and integrated measurements revealed gender-related effects across the climatic gradient (P < 0.01). Reproduction investment has an effect on the physiological performance and growth of C. album. Gender responses are site-specific, being influenced by climate. The increase in physiological stress with aridity could lead to the potential retreat and variation in structure in these populations if genders are affected differently by the predicted climate change.