title: The effect of phenological variation in sex expression on female reproductive success in Saxifraga granulata.
abstract: OBJECTIVE
  Differences in timing of flowering within and among protandrous plants shift the floral sex ratio from male to female dominance during the flowering season. Hence, the number of seeds produced by a single flower depends on traits of the flower itself (e.g., allocation to male and female function, position within an inflorescence, and flower size), as well as plant traits (e.g., timing of flowering, number of flowers, and plant height). Although it is clear that characteristics of individual flowers and whole plants can affect the number of seeds produced per flower, their relative importance for plant fitness remains largely unknown.
  
  
  METHODS
  We examined how phenological sex expression affected seed number per flower in two populations of the protandrous grassland herb Saxifraga granulata. Seed number was assessed for >1200 flowers and related to their position within an inflorescence, male and female phase duration, timing of flowering, number of flowers per plant, and plant height.
  
  
  RESULTS
  Seed number within and among plants decreased significantly over time. Early lateral flowers were larger and produced more seeds in comparison to late lateral flowers, indicating that flower position significantly affected seed number through its combined effect on sex allocation, timing of flowering, and attractiveness.
  
  
  CONCLUSIONS
  Our results showed that female reproductive success of a single flower was best explained by its position within an inflorescence and that plant traits such as first flowering date and number of flowers per plant had a smaller impact on seed number per flower.
authors.affiliation: KU Leuven, Biology Department, Plant Conservation and Population Biology, Kasteelpark Arenberg 31-bus 02435 B-3001, Heverlee, Belgium sascha.vandermeer@bio.kuleuven.be.
authors.forename: Sascha
authors.initials: S
authors.lastname: van der Meer
authors.affiliation: KU Leuven, Biology Department, Plant Conservation and Population Biology, Kasteelpark Arenberg 31-bus 02435 B-3001, Heverlee, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: Jacquemyn
mesh_terms: D001530:Belgium; D035264:Flowers / Q000502:physiology*; D012098:Reproduction; D031995:Saxifragaceae / Q000502:physiology*; D012621:Seasons
keywords: first flowering date; flowering phenology; gender; protandry; reproductive ecology; seed production; sex allocation; within-plant variation