title: Light availability affects sex lability in a gynodioecious plant.
abstract: OBJECTIVE
  Sex lability (i.e., gender diphasy) in plants is classically linked to the larger resource needs associated with the female sexual function (i.e., seed production) compared to the male function (i.e., pollen production). Sex lability in response to the environment is extensively documented in dioecious species, but has been largely overlooked in gynodioecious plants.
  
  
  METHODS
  Here, we tested whether environmental conditions induce sex lability in the gynodioecious Geranium sylvaticum. We conducted a transplantation experiment in the field where plants with different sex expression were reciprocally transplanted between high light and low light habitats. We measured plants' reproductive output and sex expression over four years.
  
  
  RESULTS
  Our results show that sex expression was labile over the study period. The light level at the destination habitat had a significant effect on sexual expression and reproductive output, because plants decreased their reproductive output when transplanted to the low light habitat. Transplantation origin did not affect any parameter measured.
  
  
  CONCLUSIONS
  This study shows that sex expression in Geranium sylvaticum is labile and related to light availability. Sexually labile plants did not produce more seeds or pollen, and thus, there was no apparent fitness gain in sexually labile individuals. Sex lability in gynodioecious plants may be more common than previously believed because detection of sex lability necessitates data on the same individuals over time, which is rare in sexually dimorphic herbaceous plants.
authors.affiliation: Department of Biological and Environmental Science, University of Jyvaskyla, P.O. Box 35 40014 Jyvaskyla, Finland svarga@lincoln.ac.uk sandravarga30@hotmail.com.
authors.forename: Sandra
authors.initials: S
authors.lastname: Varga
authors.affiliation: Department of Biological and Environmental Science, University of Jyvaskyla, P.O. Box 35 40014 Jyvaskyla, Finland.
authors.forename: Minna-Maarit
authors.initials: MM
authors.lastname: Kytöviita
mesh_terms: D017753:Ecosystem; D031315:Geranium / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D011058:Pollen / Q000502:physiology / Q000528:radiation effects; D012098:Reproduction; D012639:Seeds / Q000502:physiology / Q000528:radiation effects
keywords: Geraniaceae; functional gender; gynodioecy; light availability; reproductive output; sex lability; sexual dimorphism