Pollinator preferences and their potential effects on floral trait diversity

The Rocky Mountain columbine, Aquilegia coerulea, is a perennial plant found in montane regions of the western United States. The visual floral traits of this plant are known to vary between populations, and so does pollinator abundance and composition. The purpose of this study was to determine the floral trait preferences of the major pollinators in order to better understand their possible role in influencing the variation of floral traits.

The major pollinators found in this system are diurnal bumblebees and crepuscular hawkmoths. In this study we used Bombus impatiens and Hyles lineata and tested the preferences of each pollinator on flower size, display size, flower color, spur length, and reward. First, we hypothesized that both pollinators preferred both larger flowers and larger floral displays. Secondly, we expected that B. impatiens would prefer blue flowers while the H. lineata, would prefer white flowers during the evening but have no color preference during the day. Thirdly, that H. lineata, should prefer flowers with longer spurs while B. impatiens foraging decisions would not be affected by spur length. Finally, we hypothesize that the pollinators will show a preference for flowers that have a greater reward (either pollen or nectar). Choice assays to determine pollinator preference for specific floral traits were performed using both real and artificial flowers.