Differences in functional traits among distinct populations of the plant invader Bunias orientalis

Plants that expand their range and become invasive in other areas may shift several functional traits in response to specific environments. However, local conditions at the place of origin may have shaped the functional traits, which may to some extent remain visible in plants growing in new habitats. The present study aimed to explore the trait variation in different plant populations of native, invasive and naturalized status of Bunias orientalis grown in common conditions in relation to the climatic conditions at their place of origin. Seeds of B. orientalis were collected from 12 populations (4 per status) in 8 countries and grown under standardized conditions in a common field garden. The variation in several functional traits related to phenology, growth and reproduction was compared among status and among populations. Phenology did not differ according to status. However, several plants of the native populations, originating from areas with low annual temperatures, did not start flowering. Plants of the invasive populations produced more leaves than natives, potentially indicating their vigor in building up vegetative biomass. Number and mass of silicles and other growth traits did not differ among status groups but varied among populations. Some of the variation in functional traits may be explained by long-term adaptations to local conditions at the areas of origin and genetic diversity, while other environmental factors differing in the novel environment may contribute to a high trait variation.