Local Phenotypic Adaptation
ANOVA indicated that each phenotype differed significantly among different groups (Table 1). K-means cluster analysis of phenotypes showed that Dim1 and Dim2 could explain 61.3% and 25.6% of the observed variation, respectively, and the cumulative contribution to the observed phenotypic variation was close to 90%. All individuals of CN clustered into one clade; the individuals of the population MS and TS in the EL group clustered into one clade, which was clearly separated from the other two populations in EL; the phenotypes of the individuals in NW and NE showed small differences and could not be clearly distinguished; and the YS and LT populations in EL were grouped with the individuals of NW and NE (Figure S4).
Among the four groups, CN showed the smallest corolla diameter, the shortest petal length, spur length, pistil length, stamen length and calyx length and the lowest chlorophyll content, followed by EL, while NW and NE showed the largest values of these phenotypes (the difference between the last two groups was small). By contrast, plant height and the number of inflorescences showed the reverse order of the above traits. EL showed the largest leaf area and perimeter, followed by CN, while the leaf area of NW and NE presented little difference, but the leaf perimeter of NW was larger than that of NE. The angle of CN was the largest, followed by those of NE and NW (the difference between them was not much), and the angle of EL was the smallest (Figure 4).
The floral characteristics except for the stamen length and angle were negatively correlated with the number of inflorescences and nutritional traits except for the chlorophyll content, while the number of inflorescences was significantly positively correlated with the plant height (Figure S5). The mean Fst for the four groups was 0.1519 (0.14949-0.15074), and the overall Qst of seven traits was higher than the mean Fst, including the corolla diameter, petal length, angle, spur length, pistil length, inflorescence number and leaf area, indicating that these traits showed local adaptations (Table 1).