title: There is more to pollinator-mediated selection than pollen limitation.
abstract: Spatial variation in pollinator-mediated selection (Δβpoll ) is a major driver of floral diversification, but we lack a quantitative understanding of its link to pollen limitation (PL) and net selection on floral traits. For 2-5 years, we quantified Δβpoll on floral traits in two populations each of two orchid species differing in PL. In both species, spatiotemporal variation in Δβpoll explained much of the variation in net selection. Selection was consistently stronger and the proportion that was pollinator-mediated was higher in the severely pollen-limited deceptive species than in the rewarding species. Within species, variation in PL could not explain variation in Δβpoll for any trait, indicating that factors influencing the functional relationship between trait variation and pollination success govern a major part of the observed variation in Δβpoll . Separating the effects of variation in mean interaction intensity and in the functional significance of traits will be necessary to understand spatiotemporal variation in selection exerted by the biotic environment.
authors.affiliation: Plant Ecology and Evolution, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18 D, SE-752 36 Uppsala, Sweden; NTNU University Museum, N-7491 Trondheim, Norway. nina.sletvold@ebc.uu.se.
authors.forename: Nina
authors.initials: N
authors.lastname: Sletvold
authors.forename: Jon
authors.initials: J
authors.lastname: Agren
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology; D056084:Genetic Fitness; D029595:Orchidaceae / Q000235:genetics*; D011058:Pollen / Q000235:genetics; D054817:Pollination / Q000235:genetics*; D012641:Selection, Genetic
keywords: Dactylorhiza lapponica; Gymnadenia conopsea; floral evolution; natural selection; plant-animal interactions; spatiotemporal variation