Water-use efficiency and relative growth rate mediate competitive interactions in Sonoran Desert winter annual plants

Jennifer R. Gremer, Sarah Kimball, Katie R. Keck, Travis E. Huxman, Amy L. Angert, D. Lawrence Venable

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Premise of the study: A functional approach to investigating competitive interactions can provide a mechanistic understanding of processes driving population dynamics, community assembly, and the maintenance of biodiversity. In Sonoran Desert annual plants, a trade-off between relative growth rate (RGR) and water-use efficiency (WUE) contributes to species differences in population dynamics that promote long-term coexistence. Traits underlying this trade-off explain variation in demographic responses to precipitation as well as life history and phenological patterns. Here, we ask how these traits mediate competitive interactions. Methods: We conducted competition trials for three species occupying different positions along the RGR-WUE trade-off axis and compared the effects of competition at high and low soil moisture. We compared competitive effect (ability to suppress neighbors) and competitive response (ability to withstand competition from neighbors) among species. Key results: The RGR-WUE trade-off predicted shifts in competitive responses at different soil moistures. The high-RGR species was more resistant to competition in high water conditions, while the opposite was true for the high-WUE species. The intermediate RGR species tended to have the strongest impact on all neighbors, so competitive effects did not scale directly with differences in RGR and WUE among competitors. Conclusions: Our results reveal mechanisms underlying long-term variation in fitness: high-RGR species perform better in years with large, frequent rain events and can better withstand competition under wetter conditions. The opposite is true for high-WUE species. Such resource-dependent responses strongly influence community dynamics and can promote coexistence in variable environments.

Original languageEnglish (US)
Pages (from-to)2009-2015
Number of pages7
JournalAmerican journal of botany
Issue number10
StatePublished - Oct 2013


  • Coexistence
  • Competition
  • Condition dependence
  • Ecophysiology
  • Erodium texanum
  • Functional traits
  • Plantago insularis
  • Stylocline micropoides
  • Trade-offs

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • Plant Science


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