title: Spatial variation in pollinator-mediated selection on phenology, floral display and spur length in the orchid Gymnadenia conopsea.
abstract: Spatial variation in plant-pollinator interactions may cause variation in pollinator-mediated selection on floral traits, but to establish this link conclusively experimental studies are needed. We quantified pollinator-mediated selection on flowering phenology and morphology in four populations of the fragrant orchid Gymnadenia conopsea, and compared selection mediated by diurnal and nocturnal pollinators in two of the populations. Variation in pollinator-mediated selection explained most of the among-population variation in the strength of directional and correlational selection. Pollinators mediated correlational selection on pairs of display traits, and on one display trait and spur length, a trait affecting pollination efficiency. Only nocturnal pollinators selected for longer spurs, and mediated stronger selection on the number of flowers compared with diurnal pollinators in one population. The two types of pollinators caused correlational selection on different pairs of traits and selected for different combinations of spur length and number of flowers. The results demonstrate that spatial variation in interactions with pollinators may result in differences in directional and correlational selection on floral traits in a plant with a semi-generalized pollination system, and suggest that differences in the relative importance of diurnal and nocturnal pollinators can cause variation in selection.
authors.affiliation: Plant Ecology and Evolution, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden.
authors.forename: Elodie
authors.initials: E
authors.lastname: Chapurlat
authors.affiliation: Plant Ecology and Evolution, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden.
authors.forename: Jon
authors.initials: J
authors.lastname: Ågren
authors.affiliation: Plant Ecology and Evolution, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden.
authors.forename: Nina
authors.initials: N
authors.lastname: Sletvold
mesh_terms: D000818:Animals; D035264:Flowers; D007915:Lepidoptera; D029595:Orchidaceae / Q000235:genetics*; D010641:Phenotype; D054817:Pollination / Q000235:genetics*; D012641:Selection, Genetic
keywords: Gymnadenia conopsea (fragrant orchid); correlational selection; diurnal vs nocturnal pollination; floral evolution; plant−animal interactions; pollinator-mediated selection; semi-generalized pollination; spatial variation