Abstract Detail

Genetics Section

Culley, Theresa M. [2], Dunbar-Wallis, Amy K. [1], Sakai, Ann K. [1], Weller, Stephen G. [1], Campbell, Diane R. [1].

Evolution of dimorphism: quantitative genetics of ecophysiological traits related to resource acquisition in the gynodioecious shrub Schiedea salicaria (Caryophyllaceae).

Sex-specific differences in resource acquisition were investigated in gynodioecious Schiedea salicaria to test the assumption of equivalent resource acquisition in models of breeding system evolution. Using a quantitative genetic approach, we measured trait means and narrow-sense heritabilities for a number of ecophysiological and biomass allocation traits in females and hermaphrodites. Sexes did not differ in mean photosynthetic rate, stomatal conductance, instantaneous water-use efficiency, or intercellular carbon dioxide concentration, but hermaphrodites had greater specific leaf area than females. In terms of biomass allocation, females had similar fruit biomass as hermaphrodites, but significantly greater seed biomass per fruit. Stomatal conductance was the o­nly ecophysiological trait that exhibited high heritability, and o­nly in hermaphrodites. There were no genetic correlations between physiological traits and morphological traits associated with biomass allocation. Consequently, the evolution of dioecy in this species is less likely to be affected by sex differences in resource acquisition than by variation in resource allocation between male and female function. This study, among the first to measure the genetic potential for the evolution of sex specific ecophysiological traits, supports previous theoretical models assuming similar resource acquisition for the different sexes.

1 - University of California, Irvine, Department of Ecology and Evolution, 321 Steinhaus Hall, UCI, Irvine, California, 92697, USA
2 - University of Cincinnati, Department of Biological Sciences, 614 Rieveschl Hall, Cincinnati, Ohio, 45221-0006, USA

Keywords:
Schiedea salicaria
ecophysiology
quantitative genetics
dimorphism
resource acquisition.

Presentation Type: Paper
Session: 41-4
Location: Peruvian (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 8:45 AM
Abstract ID:519