Phenotypic plasticity of Capsella bursa-pastoris (Brassicaceae) and its effect on fitness in response to temperature and soil moisture

Abstract

Capsella bursa-pastoris is one of the most common plants on earth. Although phenotypic plasticity of ecologically important traits possibly contributes to its wide geographic range, little is known about the plasticity of C. bursa-pastoris and its effects on its fitness. In a laboratory, we assessed the phenotypic plasticity in response to two representative climatic conditions: temperature and soil moisture. In addition, we quantitatively evaluated the relationship between phenotypic plasticity and fruit production. Most measured morphological and physiological traits exhibited plastic responses to temperature and fitness based on fruit production was maintained across temperatures. In contrast, no plasticity to soil moisture was detected, and plants produced fewer fruits in dry soil. Selection analysis revealed that the plasticity of the flowering time and the water-use efficiency had positive effects on fruit production over the tested temperature regime. These experimental results suggest that phenotypic plasticity probably enables C. bursa-pastoris to cope with heterogeneous temperature environments and thereby probably contributes to its wide geographic range.