title: Functional Significance of Labellum Pattern Variation in a Sexually Deceptive Orchid (Ophrys heldreichii): Evidence of Individual Signature Learning Effects.
abstract: Mimicking female insects to attract male pollinators is an important strategy in sexually deceptive orchids of the genus Ophrys, and some species possess flowers with conspicuous labellum patterns. The function of the variation of the patterns remains unresolved, with suggestions that these enhance pollinator communication. We investigated the possible function of the labellum pattern in Ophrys heldreichii, an orchid species in which the conspicuous and complex labellum pattern contrasts with a dark background. The orchid is pollinated exclusively by males of the solitary bee, Eucera berlandi. Comparisons of labellum patterns revealed that patterns within inflorescences are more similar than those of other conspecific plants. Field observations showed that the males approach at a great speed and directly land on flowers, but after an unsuccessful copulation attempt, bees hover close and visually scan the labellum pattern for up to a minute. Learning experiments conducted with honeybees as an accessible model of bee vision demonstrated that labellum patterns of different plants can be reliably learnt; in contrast, patterns of flowers from the same inflorescence could not be discriminated. These results support the hypothesis that variable labellum patterns in O. heldreichii are involved in flower-pollinator communication which would likely help these plants to avoid geitonogamy.
authors.affiliation: Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Vienna, Austria.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Stejskal
authors.affiliation: Department of Behavioral Physiology and Sociobiology, Biozentrum, University of Wuerzburg, Würzburg, Germany.|current address: Department of Neurobiology, Faculty of Life Sciences, University of Vienna, Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Streinzer
authors.affiliation: Department of Physiology, Monash University, Clayton, Australia.|School of Media and Communication, RMIT University, Melbourne, Australia.
authors.forename: Adrian
authors.initials: A
authors.lastname: Dyer
authors.affiliation: Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Vienna, Austria.
authors.forename: Hannes F
authors.initials: HF
authors.lastname: Paulus
authors.affiliation: Department of Behavioral Physiology and Sociobiology, Biozentrum, University of Wuerzburg, Würzburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Spaethe
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology; D001522:Behavior, Animal; D003307:Copulation; D005260:Female; D035264:Flowers / Q000033:anatomy & histology*; D007858:Learning; D008297:Male; D029595:Orchidaceae / Q000502:physiology*