| Recently, fluctuating asymmetry (FA), the small random deviations between left and right sides of a character, has been proposed as an indicator of nectar levels and of overall plant value to a pollinator. I tested the generality of this hypothesis in two ways: first, by assessing whether plants show reduced seed set as a result of pollinator avoidance of high floral FA; second, by assessing whether bumblebee pollinators use floral symmetry as a cue in intraspecific flower choices, thus exerting a selective pressure against individuals with high FA.;Flowers from three species of perennial herbs in Ontario, Hesperis matronalis, Calopogon tuberosus, and Epilobium angustifolium, were manipulated in the field to create four levels of floral asymmetry, and seed set after open pollination was assessed. There were no differences in seed set among the four classes of asymmetry.;I performed three studies to assess the importance of petal symmetry in affecting pollinator behaviour: first, by "interviewing" freely foraging bumblebees with a small array of manipulated flowers; second, by "interrogating" individual bees in flight cages using conspecific flowers collected from natural populations of H. matronalis and E. angustifolium. Bees visited flowers indiscriminately in all cases. In a third study, I found that bees trained to prefer asymmetrical outlines performed no better than those trained to prefer symmetrical ones when choosing outlines from a mixed group. (Abstract shortened by UMI.)... |
