Morphological plasticity and adaptation level of distylous Primula nivalis in a heterogeneous alpine environment

Plant populations at high elevation face extreme climatic conditions and resource limitations. The existence of distylous species at different elevations can help us investigate their adaptation to high altitudes, the evolution of their morphological characteristics, as well as their responses to limited resources. Here, 17 populations of Primula nivalis at different elevations were evaluated regarding variations in plant morphological characteristics, biomass allocation, and morphological plasticity in a heterogeneous environment. Our results demonstrate that heterogeneous environments can affect plant morphological characteristics and resource allocation in each sexual morph of these plants. Moreover, environmental variations reduced morphological plasticity in the two plant morphs, and the plasticity of long style (LS) plants was greater than that of short style (SS) plants. There were significant negative correlations between morphological characteristics and elevation, rainfall, temperature, and sunshine, and these are the main variables that affect morphological characteristics and resource allocation of both morphs of P. nivalis plants in heterogeneous environments. The morphological characteristics of P. nivalis plants transplanted from high to lower elevations were not significantly different in either population. LS plants had greater morphological plasticity and adaptability in heterogeneous environments than SS plants. Elevational gradients and heterogeneous environments differentiated both morphs of P. nivalis plants with regards to morphology as well as adaptations. LS plants showed a higher level of adaptability than SS plants.