Geographic Variation in Progeny: Climatic and Soil Changes in Offspring Size and Colour in Four Sorbus spp. (Rosaceae)

Abstract

To investigate resource allocation and adaptation strategies of Sorbus spp. under different environment and soil conditions, four Sorbus L. species (Sorbus hupehensis C. K. Schneid, Sorbus pohuashanensis (Hance) Hedl, Sorbus discolor (Maxim.) Maxim, Sorbus koehneana C. K. Schneid) were selected as the study materials. Phenotypic traits including seed mass, fruit mass, and fruit colour were measured and analyzed. Linear Mixed-Effects Models were employed to analyze the associations between phenotypic traits and the environment, and the Maxent model was used to predict the potential distribution areas. Our study reveals that Sorbus spp. tend to prioritize seed production to increase their survival ability in nutrient-poor environments, while they tend to lean towards fruit production in nutrient-rich environments. Specifically, S. pohuashanensis has fruit skin rich in carotenoids and anthocyanins, with the degree of fruit colouration being positively correlated with the environmental suitability. However, the other three spp. demonstrate the opposite pattern. S. pohuashanensis is found to be most suitable for growth in mountainous areas around 40° N, and it is adapted to low temperatures. S. hupehensis prefers warm regions and is distributed in southern Shanxi, while S. discolor has a wider range of adaptability. These results provide a scientific basis for the protection and rational utilization of Sorbus spp. by elucidating their ecological adaptation abilities.