Priorities for research on priority effects

David Johnson

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


Our ability to measure both the composition and function of mycorrhizal fungal communities has increased markedly in the last decade or so, and several studies have made progress in understanding relationships between these two properties. More often than not, such biodiversity–ecosystem function experiments involve artificially assembling communities and testing subsequent effects on ecologically important processes, fluxes and pools. In the context of mycorrhizal fungi, rather less attention has been paid to the processes governing the development of communities themselves. One potentially important factor is the order and timing in which individuals arrive on a host, that is, priority effects. Priority effects can shape community development by being both positive, where a pioneer facilitates subsequent colonization of a host by additional individuals, and negative, where the abundance of subsequent individuals is reduced. In ectomycorrhizal (ECM) fungi, priority effects have been shown for a number of species in the early stages of colonization of pine seedlings (Kennedy & Bruns, 2005; Kennedy et al., 2009). In this issue of New Phytologist, Werner & Kiers (pp. 1515–1524) test for priority effects in arbuscular mycorrhizal (AM) fungi using quantitative molecular genetics and classical visual observations of roots in combination with a rigorous experimental design. Their analysis showed that the abundance of an invading AM fungus in Medicago truncatula roots was always suppressed when the root systems were already colonized, and these effects held for two species of fungi (Glomus aggregatum and Rhizophagus irregularis). They also found that the reduction in abundance of the invader depended on the length of time the roots had been colonized by the pioneer; marginal effects were seen after 2 wk while significant effects were observed after 4 wk. Their findings are important, not just because it is the first demonstration that AM fungal communities on roots can be shaped by their timing and order of arrival, but also because it immediately opens up several new lines of inquiry related primarily to the mechanisms of priority effects as would occur in nature.
Original languageEnglish
Pages (from-to)1375-1377
Number of pages3
JournalNew Phytologist
Issue number4
Early online date3 Feb 2015
Publication statusPublished - Mar 2015


  • arbuscular mycorrhizal (AM) fungi
  • arrival order
  • colonization
  • common mycelial network
  • community development
  • ectomycorrhizal (ECM) fungi
  • niche-component hypotheses
  • priority effects


Dive into the research topics of 'Priorities for research on priority effects'. Together they form a unique fingerprint.

Cite this