title: Changing reproductive effort within a semelparous reproductive episode.
abstract: •
  
  
  OBJECTIVE
  Life-history theory predicts a trade-off between current and future reproduction for iteroparous organisms-as individuals age, the expected value of future reproduction declines, and thus reproductive effort is expected to be higher in later clutches than in earlier. In contrast, models explaining the evolution of semelparity treat semelparous reproduction as instantaneous, with no scope for intraindividual variation. However, semelparous reproduction is also extended, but over shorter time scales; whether there are similar age- or stage-specific changes in reproductive effort within a semelparous episode is unclear. In this study, we assessed whether semelparous individuals increase reproductive effort as residual reproductive value declines by comparing the reproductive phenotype of flowers at five different floral positions along a main inflorescence.•
  
  
  METHODS
  Using the herbaceous monocarp Lobelia inflata, we conducted a longitudinal study of 409 individuals including both laboratory and field populations over three seasons. We recorded six reproductive traits-including the length of three phenological intervals as well as fruit size, seed size, and seed number-for all plants across floral positions produced throughout the reproductive episode.•
  
  
  RESULTS
  We found that while the rate of flower initiation did not change, flowers at distal (late) floral positions developed more quickly and contained larger seed than flowers at basal (early) floral positions did.•
  
  
  CONCLUSIONS
  Our results were consistent with the hypothesis that, like iteroparous organisms, L. inflata increases reproductive effort in response to low residual reproductive value.
authors.affiliation: Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada, K1S 5B6.
authors.forename: P William
authors.initials: PW
authors.lastname: Hughes
authors.affiliation: Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada, K1S 5B6.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Simons
mesh_terms: D035264:Flowers / Q000254:growth & development*; D005638:Fruit; D056626:Inflorescence; D029746:Lobelia / Q000254:growth & development / Q000502:physiology*; D010641:Phenotype; D012098:Reproduction / Q000502:physiology; D012639:Seeds
keywords: Campanulaceae; Lobelia inflata; iteroparity; life history evolution; monocarpy; reproductive effort; semelparity