, Volume 88, Issue 1, pp 84–90 | Cite as

Ecological genetics of Bromus tectorum

II. Intraspecific variation in phenotypic plasticity
  • Kevin J. Rice
  • Richard N. Mack
Original Papers


For Bromus tectorum, an alien annual grass now widespread in western North America, we assessed the sensitivity of the phenotypic expression of populational differences in phenology and demography to variation in plant density. Plants were grown in an unheated glasshouse from seeds collected from six habitat types located along a moisture-temperature gradient. Survival to flowering was high with a mean overall survival of 91%. Survival was highest among plants from the coolest, most mesic site. Time to first flowering decreased at the higher sowing density and was dependent on seed source. Plant dry weight and average seed production was lowest within high density plots; the magnitude of this reduction was significantly dependent on seed source. Individual seed weight was also dependent on the interaction of seed source and sowing density. Seed weight did not vary as much as seed number or plant weight in response to density. Differences among sources in hierarchies of plant size and seed production were detected at low sowing densities. The degree of inequality in the distributions of plant size and seed number increased at high density.

Key words

Bromus tectorum Density effects Ecological genetics Phenotypic plasticity Reproductive hierarchies 


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Copyright information

© Springer-Verlag 1991

Authors and Affiliations

  • Kevin J. Rice
    • 1
  • Richard N. Mack
    • 2
  1. 1.Department of Agronomy and Range ScienceUniversity of CaliforniaDavisUSA
  2. 2.Department of BotanyWashington State UniversityPullmanUSA

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