title: The role of pollinators in maintaining variation in flower colour in the Rocky Mountain columbine, Aquilegia coerulea.
abstract: OBJECTIVE
  Flower colour varies within and among populations of the Rocky Mountain columbine, Aquilegia coerulea, in conjunction with the abundance of its two major pollinators, hawkmoths and bumble-bees. This study seeks to understand whether the choice of flower colour by these major pollinators can help explain the variation in flower colour observed in A. coerulea populations.
  
  
  METHODS
  Dual choice assays and experimental arrays of blue and white flowers were used to determine the preference of hawkmoths and bumble-bees for flower colour. A test was made to determine whether a differential preference for flower colour, with bumble-bees preferring blue and hawkmoths white flowers, could explain the variation in flower colour. Whether a single pollinator could maintain a flower colour polymorphism was examined by testing to see if preference for a flower colour varied between day and dusk for hawkmoths and whether bumble-bees preferred novel or rare flower colour morphs.
  
  
  RESULTS
  Hawkmoths preferred blue flowers under both day and dusk light conditions. Naïve bumble-bees preferred blue flowers but quickly learned to forage randomly on the two colour morphs when similar rewards were presented in the flowers. Bees quickly learned to associate a flower colour with a pollen reward. Prior experience affected the choice of flower colour by bees, but they did not preferentially visit novel flower colours or rare or common colour morphs.
  
  
  CONCLUSIONS
  Differences in flower colour preference between the two major pollinators could not explain the variation in flower colour observed in A. coerulea. The preference of hawkmoths for flower colour did not change between day and dusk, and bumble-bees did not prefer a novel or a rare flower colour morph. The data therefore suggest that factors other than pollinators may be more likely to affect the flower colour variation observed in A. coerulea.
authors: Department of Entomology, 1630 Linden Drive, University of Wisconsin, Madison, WI 53706, USA and USDA-Agricultural Research Service, Vegetable Crop Research Unit, 1630 Linden Drive, Madison, WI 53706, USA.
authors: Margaret W
authors: MW
authors: Thairu
authors: Department of Entomology, 1630 Linden Drive, University of Wisconsin, Madison, WI 53706, USA and USDA-Agricultural Research Service, Vegetable Crop Research Unit, 1630 Linden Drive, Madison, WI 53706, USA Department of Entomology, 1630 Linden Drive, University of Wisconsin, Madison, WI 53706, USA and USDA-Agricultural Research Service, Vegetable Crop Research Unit, 1630 Linden Drive, Madison, WI 53706, USA jbrunet@wisc.edu Johanne.Brunet@ars.usda.gov.
authors: Johanne
authors: J
authors: Brunet
mesh_terms: D000818:Animals; D031884:Aquilegia / Q000502:physiology*; D001516:Bees / Q000502:physiology*; D002755:Choice Behavior; D003116:Color; D035264:Flowers / Q000502:physiology*; D009036:Moths / Q000502:physiology*; D010858:Pigmentation; D011058:Pollen / Q000502:physiology; D054817:Pollination / Q000502:physiology*
keywords: Aquilegia coerulea; Bombus impatiens; Hyles lineata; Ranunculaceae; Rocky Mountain columbine; bumble-bees; flower colour variation; frequency dependence; hawkmoths; learning behaviour; novelty; pollinators