| Title: | A pollinators' eye view of a shelter mimicry system |
| Author(s): | Vereecken NJ; Dorchin A; Dafni A; Hotling S; Schulz S; Watts S; |
| Address: | "Evolutionary Biology & Ecology, Free University of Brussels/Universite Libre de Bruxelles, Av. F.D. Roosevelt 50, Brussels, Belgium. nicolas.vereecken@ulb.ac.be" |
| ISSN/ISBN: | 1095-8290 (Electronic) 0305-7364 (Print) 0305-7364 (Linking) |
| Abstract: | "BACKGROUND AND AIMS: 'Human-red' flowers are traditionally considered to be rather unpopular with bees, yet some allogamous species in the section Oncocyclus (genus Iris, Iridaceae) have evolved specialized interactions with their pollinators, a narrow taxonomic range of male solitary bees. The dark-red, tubular flowers of these irises are nectarless but provide protective shelters (i.e. a non-nutritive form of reward) primarily to male solitary bees (Apidae, Eucerini) that pollinate the flowers while looking for a shelter. An earlier study on orchids suggested that species pollinated predominantly by male solitary bees produce significantly larger amounts and larger numbers of different n-alkenes (unsaturated cuticular hydrocarbons). Whether or not this also applies to the Oncocyclus irises and whether pollinators are attracted by specific colours or scents of these flowers is unknown. METHODS: Using Iris atropurpurea, recording of pollinator preferences for shelters with different spatial parameters was combined with analyses of floral colours (by spectrophotometry) and scents (by gas chromatography-mass spectrometry) to test the hypotheses that (a) pollinators significantly prefer floral tunnels facing the rising sun (floral heat-reward hypothesis), and that (b) flowers pollinated predominantly by male solitary bees produce significantly larger amounts and larger numbers of unsaturated cuticular hydrocarbons (n-alkenes) in their floral scent (preadaptation to sexual-deception hypothesis). KEY RESULTS: Male bees do not significantly prefer shelters facing the rising sun or with the presence of high absolute/relative amounts and numbers of n-alkenes in the floral scent. CONCLUSIONS: The results suggest that the flowers of I. atropurpurea probably evolved by pollinator-mediated selection acting primarily on floral colours to mimic large achromatic ('bee-black') protective shelters used preferentially by male solitary bees, and that pollinator visits are presumably not the result of an odour-based sexual stimulation or motivated by an increased morning floral heat reward in tunnels facing the rising sun" |
| Keywords: | "*Adaptation, Biological Animals Bees/*physiology Biological Evolution Color Flowers/*anatomy & histology Iris Plant/*anatomy & histology Male Odorants Phenotype *Pollination Iris atropurpurea Oncocyclus Shelter mimicry floral colours floral evolution flor;" |
| Notes: | "MedlineVereecken, Nicolas J Dorchin, Achik Dafni, Amots Hotling, Susann Schulz, Stefan Watts, Stella eng Research Support, Non-U.S. Gov't England 2013/04/20 Ann Bot. 2013 Jun; 111(6):1155-65. doi: 10.1093/aob/mct081. Epub 2013 Apr 17" |
