Coexistence of identical competitors: an old doctrine challenged

An illustrious principle in ecology states that no two identical species may coexist: sooner or later all but one will drift to extinction. Researchers from the Beijing Normal University and the University of Helsinki have modeled recent data on fig-pollinating wasps that appear to contradict the old theory.

The model, which is reported in a forthcoming issue of Ecology Letters, is built upon the evolutionary local mate competition theory, which is empirically strongly supported for fig wasps.

Zhang, Lin, and Hanski show how this mechanism leads to a demographic advantage to uncommon species, which helps identical competitors coexist. This prediction accords with the discovery of cryptic species of fig wasps made by researchers using molecular markers.

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