title: Floral visual signal increases reproductive success in a sexually deceptive orchid.
abstract: Sexually deceptive orchids mimic signals emitted by female insects in order to attract mate-searching males. Specific attraction of the targeted pollinator is achieved by sex pheromone mimicry, which constitutes the major attraction channel. In close vicinity of the flower, visual signals may enhance attraction, as was shown recently in the sexually deceptive orchidOphrys heldreichii. Here, we conducted an in situ manipulation experiment in two populations ofO. heldreichiion Crete to investigate whether the presence/absence of the conspicuous pink perianth affects reproductive success in two natural orchid populations. We estimated reproductive success of three treatment groups (with intact, removed and artificial perianth) throughout the flowering period as pollinaria removal (male reproductive success) and massulae deposition (female reproductive success). Reproductive success was significantly increased by the presence of a strong visual signal-the conspicuous perianth-in one study population, however, not in the second, most likely due to the low pollinator abundance in the latter population. This study provides further evidence that the coloured perianth inO. heldreichiiis adaptive and thus adds to the olfactory signal to maximise pollinator attraction and reproductive success.
authors.affiliation: Department of Evolutionary Biology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: Demetra
authors.initials: D
authors.lastname: Rakosy
authors.forename: Martin
authors.initials: M
authors.lastname: Streinzer
authors.forename: Hannes F
authors.initials: HF
authors.lastname: Paulus
authors.forename: Johannes
authors.initials: J
authors.lastname: Spaethe
keywords: Eucera berlandi; Male bees; Ophrys heldreichii; Pollination; Sexual deception