title: Similar gender dimorphism in the costs of reproduction across the geographic range of Fraxinus ornus.
abstract: OBJECTIVE
  The reproductive costs for individuals with the female function have been hypothesized to be greater than for those with the male function because the allocation unit per female flower is very high due to the necessity to nurture the embryos until seed dispersal occurs, while the male reproductive allocation per flower is lower because it finishes once pollen is shed. Consequently, males may invest more resources in growth than females. This prediction was tested across a wide geographical range in a tree with a dimorphic breeding system (Fraxinus ornus) consisting of males and hermaphrodites functioning as females. The contrasting ecological conditions found across the geographical range allowed the evaluation of the hypothesis that the reproductive costs of sexual dimorphism varies with environmental stressors.
  
  
  METHODS
  By using random-effects meta-analysis, the differences in the reproductive and vegetative investment of male and hermaphrodite trees of F. ornus were analysed in 10 populations from the northern (Slovakia), south-eastern (Greece) and south-western (Spain) limits of its European distribution. The variation in gender-dimorphism with environmental stress was analysed by running a meta-regression between these effect sizes and the two environmental stress indicators: one related to temperature (the frost-free period) and another related to water availability (moisture deficit).
  
  
  RESULTS
  Most of the effect sizes showed that males produced more flowers and grew more quickly than hermaphrodites. Gender differences in reproduction and growth were not minimized or maximized under adverse climatic conditions such as short frost-free periods or severe aridity.
  
  
  CONCLUSIONS
  The lower costs of reproduction for F. ornus males allow them to grow more quickly than hermaphrodites, although such differences in sex-specific reproductive costs are not magnified under stressful conditions.
authors.affiliation: Centro de Investigaciones sobre Desertificación (CSIC-UV-GV), Apartado Oficial, 46470 Albal, Valencia, Spain. Miguel.Verdu@uv.es
authors.forename: Miguel
authors.initials: M
authors.lastname: Verdú
authors.forename: Kostas
authors.initials: K
authors.lastname: Spanos
authors.forename: Ingrid
authors.initials: I
authors.lastname: Canová
authors.forename: Branko
authors.initials: B
authors.lastname: Slobodník
authors.forename: Ladislav
authors.initials: L
authors.lastname: Paule
mesh_terms: D002980:Climate; D035264:Flowers / Q000502:physiology*; D031661:Fraxinus / Q000502:physiology*; D005843:Geography; D019083:Mediterranean Region; D012098:Reproduction / Q000502:physiology; D012727:Sex Characteristics; D014867:Water / Q000502:physiology
chemical_list: D014867:Water