title: Evolutionary consequences of ecological factors: pollinator reliability predicts mating-system traits of a perennial plant.
abstract: The reproductive-assurance hypothesis predicts that mating-system traits will evolve towards increased autonomous self-pollination in plant populations experiencing unreliable pollinator service. We tested this long-standing hypothesis by assessing geographic covariation among pollinator reliability, outcrossing rates, heterozygosity and relevant floral traits across populations of Dalechampia scandens in Costa Rica. Mean outcrossing rates ranged from 0.16 to 0.49 across four populations, and covaried with the average rates of pollen arrival on stigmas, a measure of pollinator reliability. Across populations, genetically based differences in herkogamy (anther-stigma distance) were associated with variation in stigmatic pollen loads, outcrossing rates and heterozygosity. These observations are consistent with the hypothesis that, when pollinators are unreliable, floral traits promoting autonomous selfing evolve as a mechanism of reproductive assurance. Extensive covariation between floral traits and mating system among closely related populations further suggests that floral traits influencing mating systems track variation in adaptive optima generated by variation in pollinator reliability.
authors.affiliation: Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.
authors.forename: Øystein H
authors.initials: ØH
authors.lastname: Opedal
authors.affiliation: Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.
authors.forename: Elena
authors.initials: E
authors.lastname: Albertsen
authors.affiliation: School of Biological Sciences, University of Portsmouth, King Henry Building, King Henry I Street, Portsmouth, PO1 2DY, UK.|Department of Biology, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.|Institute of Arctic Biology, University of Alaska, Fairbanks, AK, 99775, USA.
authors.forename: W Scott
authors.initials: WS
authors.lastname: Armbruster
authors.affiliation: School of Biological Sciences, University of Portsmouth, King Henry Building, King Henry I Street, Portsmouth, PO1 2DY, UK.
authors.forename: Rocío
authors.initials: R
authors.lastname: Pérez-Barrales
authors.affiliation: School of Biology and Center of Excellence in Phylogeny of Living Organisms, University of Tehran, 14155-6455, Tehran, Iran.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Falahati-Anbaran
authors.affiliation: Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NTNU, 7491, Trondheim, Norway.
authors.forename: Christophe
authors.initials: C
authors.lastname: Pélabon
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology*; D003364:Costa Rica; D003433:Crosses, Genetic; D019665:Euphorbiaceae / Q000235:genetics* / Q000502:physiology*; D005260:Female; D035264:Flowers; D005838:Genotype; D006579:Heterozygote; D000071422:Inbreeding Depression; D008297:Male; D018895:Microsatellite Repeats; D011058:Pollen / Q000502:physiology*; D054817:Pollination / Q000502:physiology*
keywords: 
  Dalechampia
  ; ecological context; herkogamy; mixed mating systems; plant-pollinator interactions; reproductive assurance