title: The mean and variability of a floral trait have opposing effects on fitness traits.
abstract: OBJECTIVE
  Floral traits are essential for ensuring successful pollination and reproduction in flowering plants. In particular, style and anther positions are key for pollination accuracy and efficiency. Variation in these traits among individuals has been well studied, but less is known about variation within flowers and plants and its effect on pollination and reproductive success.
  
  
  METHODS
  Style deflexion is responsible for herkogamy and important for pollen deposition in Passiflora incarnata. The degree of deflexion may vary among stigmas within flowers as well as among flowers. We measured the variability of style deflexion at both the flower and the plant level. The fitness consequences of the mean and variation of style deflexion were then evaluated under natural pollination by determining their relationship to pollen deposition, seed production and average seed weight using structural equation modelling. In addition, the relationship between style deflexion and self-pollen deposition was estimated in a greenhouse experiment.
  
  
  RESULTS
  We found greater variation in style deflexion within flowers and plants than among plants. Variation of style deflexion at the flower and plant level was positively correlated, suggesting that variability in style deflexion may be a distinct trait in P. incarnata. Lower deflexion and reduced variation in that deflexion increased pollen deposition, which in turn increased seed number. However, lower styles also increased self-pollen deposition. In contrast, higher deflexion and greater variability of that deflexion increased variation in pollen deposition, which resulted in heavier seeds.
  
  
  CONCLUSIONS
  Variability of style deflexion and therefore stigma placement, independent from the mean, appears to be a property of individual P. incarnata plants. The mean and variability of style deflexion in P. incarnata affected seed number and seed weight in contrasting ways, through the quantity and potentially quality of pollen deposition. This antagonistic selection via different fitness components may maintain diverse style phenotypes.
authors.affiliation: School of Resources and Environmental Science, Hubei University, Wuhan 430062, China, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Wuhan 430062, China, Hubei Provincial Key Laboratory of Regional Development and Environmental Response, Wuhan 430062, China and daican@hubu.edu.cn.
authors.forename: Can
authors.initials: C
authors.lastname: Dai
authors.affiliation: School of Resources and Environmental Science, Hubei University, Wuhan 430062, China.
authors.forename: Xijian
authors.initials: X
authors.lastname: Liang
authors.affiliation: Department of Biology, University of Virginia, Charlottesville, VA 22903, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Ren
authors.affiliation: School of Resources and Environmental Science, Hubei University, Wuhan 430062, China.
authors.forename: Minglin
authors.initials: M
authors.lastname: Liao
authors.affiliation: School of Resources and Environmental Science, Hubei University, Wuhan 430062, China.
authors.forename: Jiyang
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Biology, University of Virginia, Charlottesville, VA 22903, USA.
authors.forename: Laura F
authors.initials: LF
authors.lastname: Galloway
mesh_terms: D035264:Flowers / Q000502:physiology*; D056084:Genetic Fitness; D008954:Models, Biological; D029598:Passiflora / Q000502:physiology*; D011058:Pollen / Q000502:physiology; D054817:Pollination / Q000502:physiology; D019655:Quantitative Trait, Heritable; D012098:Reproduction
keywords: CV; Passiflora incarnata; anther–stigma separation; floral traits; intra-floral variation; seed number; seed weight; structural equation modelling; style deflexion.