Figure 1. Study species and the study sites. (a) Yellow flower and (b) red flower of A. buergeriana var. buergeriana . (c) Measurement of floral spur length and bumblebee size. (d) Locations of the 16 surveyed populations in the four mountain regions (populations are indicated by ”Population no. Region abbreviation-altitude [in meters]”. The size of the purple circle at each site indicates the average spur length of the flowers at that site (spur length was not observed in the 10 ON-1340 population).