title: Can selection on a male mating character result in evolutionary change? A selection experiment on California wild radish, Raphanus sativus.
abstract: OBJECTIVE
  Whenever more pollen grains arrive on stigmas than necessary to fertilize ovules, sexual selection is possible. However, the role of sexual selection remains controversial, in part because of lack of evidence on genetic bases of traits and the response of relevant characters to selection.
  
  
  METHODS
  In an experiment with Raphanus sativus, we selected on tendency to sire seeds in the stylar or basal regions of fruits. This character is likely related to pollen tube growth rate, and seed position affects rates of abortion and seed predation. We measured differences among families in seed siring and related characters and evaluated responses to selection.
  
  
  RESULTS
  All replicates showed strong effects of pollen donor family on proportion of seeds sired per fruit in mixed pollinations. Most also showed effects of pollen donor family on number of pollen grains per flower and pollen diameter. Two of four replicates showed a response to selection on position of seeds sired. In responding replicates, we found trade-offs in pollen grain size and number; plants with larger pollen grains sired more seeds in the basal region.
  
  
  CONCLUSIONS
  Our data suggest a genetic basis for pollen donor ability to sire seeds in competition. The significant response to selection in two replicates shows that position of seeds sired can respond to selection. Thus, all components for sexual selection to occur and affect traits are present. Variation in results among replicates might be due to changes in greenhouse conditions. Environmental effects may contribute to the maintenance of variation in these fitness-related characters.
authors.affiliation: Department of Biology, MSC03-2020, 1 University of New Mexico, Albuquerque, New Mexico 87131 USA marshall@unm.edu.
authors.forename: Diane L
authors.initials: DL
authors.lastname: Marshall
authors.affiliation: Department of Biology, 99 Thomas Nelson Drive, Thomas Nelson Community College, Hampton, Virginia 23666 USA.
authors.forename: Ann S
authors.initials: AS
authors.lastname: Evans
mesh_terms: D000704:Analysis of Variance; D005075:Biological Evolution; D016009:Chi-Square Distribution; D008954:Models, Biological; D011058:Pollen / Q000502:physiology; D054817:Pollination; D031224:Raphanus / Q000502:physiology*; D012639:Seeds / Q000502:physiology; D012641:Selection, Genetic
keywords: Brassicaceae; Raphanus sativus; nonrandom mating; pollen competition; selection experiment; sexual selection; wild radish