title: Uniform female-biased sex ratios in alpine willows.
abstract: OBJECTIVE
  The development of biased sex ratios in dioecious plant species has been ascribed to either (1) factors influencing differential adult mortality of male and female plants or (2) factors acting at an early life stage that determine seed sex ratio or seedling survival.
  
  
  METHODS
  To discriminate between these two competing hypotheses, we surveyed sex and age of 379 individuals from five species of the genus Salix across 11 alpine valleys in the southwest Yukon.
  
  
  RESULTS
  We observed uniformly female-biased sex ratios of approximately 2:1 across all adult age cohorts and patch sizes of the five willow species. No spatial variation in sex ratio occurred that could be associated with site-specific characteristics such as elevation or aspect.
  
  
  CONCLUSIONS
  Our results indicate that the female-biased sex ratios in the alpine willow species investigated in this study are not a consequence of ecological processes acting on established adult plants. The sex ratio is instead determined at an early life stage by a mechanism that remains unknown.
authors: Department of Biological Sciences, CW405 Biological Sciences Bldg., University of Alberta, Edmonton, AB, Canada. imyerssmith@ualberta.ca
authors: Isla H
authors: IH
authors: Myers-Smith
authors: David S
authors: DS
authors: Hik
mesh_terms: D017753:Ecosystem; D032108:Salix; D012744:Sex Ratio; D015874:Yukon Territory