Long-term nitrogen addition causes the evolution of less-cooperative mutualists

Dylan J. Weese, Katy D. Heath, Bryn T.M. Dentinger, Jennifer A. Lau

Research output: Contribution to journalArticlepeer-review


Human activities have altered the global nitrogen (N) cycle, and as a result, elevated N inputs are causing profound ecological changes in diverse ecosystems. The evolutionary consequences of this global change have been largely ignored even though elevated N inputs are predicted to cause mutualism breakdown and the evolution of decreased cooperation between resource mutualists. Using a long-term (22 years) N-addition experiment, we find that elevated N inputs have altered the legume-rhizobium mutualism (where rhizobial bacteria trade N in exchange for photosynthates from legumes), causing the evolution of less-mutualistic rhizobia. Plants inoculated with rhizobium strains isolated from N-fertilized treatments produced 17-30% less biomass and had reduced chlorophyll content compared to plants inoculated with strains from unfertilized control plots. Because the legume-rhizobium mutualism is the major contributor of naturally fixed N to terrestrial ecosystems, the evolution of less-cooperative rhizobia may have important environmental consequences.

Original languageEnglish (US)
Pages (from-to)631-642
Number of pages12
Issue number3
StatePublished - Mar 1 2015


  • Adaptation
  • Coevolution
  • Nitrogen deposition
  • Resource mutualism
  • Symbiosis

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • Agricultural and Biological Sciences(all)


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