Loss of functionally unique species may gradually undermine ecosystems

E.J. O'Gorman, J.M. Yearsley, T.P. Crowe, Mark Emmerson, U. Jacob, O.L. Petchey

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


Functionally unique species contribute to the functional diversity of natural systems, often enhancing ecosystem functioning. An abundance of weakly interacting species increases stability in natural systems, suggesting that loss of weakly linked species may reduce stability. Any link between the functional uniqueness of a species and the strength of its interactions in a food web could therefore have simultaneous effects on ecosystem functioning and stability. Here, we analyse patterns in 213 real food webs and show that highly unique species consistently tend to have the weakest mean interaction strength per unit biomass in the system. This relationship is not a simple consequence of the interdependence of both measures on body size and appears to be driven by the empirical pattern of size structuring in aquatic systems and the trophic position of each species in the web. Food web resolution also has an important effect, with aggregation of species into higher taxonomic groups producing a much weaker relationship. Food webs with fewer unique and less weakly interacting species also show significantly greater variability in their levels of primary production. Thus, the loss of highly unique, weakly interacting species may eventually lead to dramatic state changes and unpredictable levels of ecosystem functioning.
Original languageEnglish
Pages (from-to)1886-1893
Number of pages8
JournalProceedings of the Royal Society of London. Series B, Biological Sciences
Issue number1713
Early online date24 Nov 2010
Publication statusPublished - Jun 2011

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Environmental Science(all)
  • Immunology and Microbiology(all)
  • Medicine(all)


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