Pollinators show flower colour preferences but flowers with similar colours do not attract similar pollinators.
Colour is one of the main floral traits used by pollinators to locate flowers. Although pollinators show innate colour preferences, the view that the colour of a flower may be considered an important predictor of its main pollinators is highly controversial because flower choice is highly context-dependent, and initial innate preferences may be overridden by subsequent associative learning. Our objective is to establish whether there is a relationship between flower colour and pollinator composition in natural communities.



We measured the flower reflectance spectrum and pollinator composition in four plant communities (85 plant species represented by 109 populations, and 32 305 plant-pollinator interactions in total). Pollinators were divided into six taxonomic groups: bees, ants, wasps, coleopterans, dipterans and lepidopterans.



We found consistent associations between pollinator groups and certain colours. These associations matched innate preferences experimentally established for several pollinators and predictions of the pollination syndrome theory. However, flowers with similar colours did not attract similar pollinator assemblages.



The explanation for this paradoxical result is that most flower species are pollination generalists. We conclude that although pollinator colour preferences seem to condition plant-pollinator interactions, the selective force behind these preferences has not been strong enough to mediate the appearance and maintenance of tight colour-based plant-pollinator associations.
CREAF, Cerdanyola del Vallès, 08193 Barcelona, Spain s.reverte@creaf.uab.cat.
Sara
S
Reverté
CREAF, Cerdanyola del Vallès, 08193 Barcelona, Spain Universitat Autònoma Barcelona, Cerdanyola del Vallès, 08193 Barcelona, Spain.
Javier
J
Retana
CSIC, Estación Experimental de Zonas Áridas, Almería, Spain Universidad de Granada, Granada, Spain.
José M
JM
Gómez
CREAF, Cerdanyola del Vallès, 08193 Barcelona, Spain.
Jordi
J
Bosch
D000818:Animals; D001516:Bees / Q000502:physiology*; D003116:Color; D035264:Flowers / Q000033:anatomy & histology* / Q000502:physiology; D010641:Phenotype; D018521:Plant Physiological Phenomena; D010944:Plants / Q000033:anatomy & histology*; D054817:Pollination / Q000502:physiology*
Colour preferences; floral colour; floral reflectance spectra; floral traits; generalization; phylogenetic signal; plant-pollinator interactions; pollination syndromes; pollinator assemblage