Intransitivity is infrequent and fails to promote annual plant coexistence without pairwise niche differences

8 páginas.-- 2 figuras.-- 41 referencias.-- 3 Additional supporting information may be found in the online version of this article at http://onlinelibrary.wiley.com/doi/10.1002/ecy.1782/suppinfoIntransitive competition is often projected to be a widespread mechanism of species coexistence in ecological communities. However, it is unknown how much of the coexistence we observe in nature results from this mechanism when species interactions are also stabilized by pairwise niche differences. We combined field-parameterized models of competition among 18 annual plant species with tools from network theory to quantify the prevalence of intransitive competitive relationships. We then analyzed the predicted outcome of competitive interactions with and without pairwise niche differences. Intransitive competition was found for just 15–19% of the 816 possible triplets, and this mechanism was never sufficient to stabilize the coexistence of the triplet when the pair-wise niche differences between competitors were removed. Of the transitive and intransitive triplets, only four were predicted to coexist and these were more similar in multidimensional trait space defined by 11 functional traits than non-coexisting triplets. Our results argue that intransitive competition may be less frequent than recently posed, and that even when it does operate, pairwise niche differences may be key to possible coexistence.Postdoctoral financial support provided by the Spanish Ministry for Education and Science (Juan de la Cierva, JCI- 2012- 12061). D. B. Stouffer acknowledges support from the Royal Society of New Zealand (via Marsden Fast- Start UOC- 1101 and a Rutherford Discovery Fellowship). N. J. B. Kraft and J. M. Levine were supported by NSF DEB 1644641Peer reviewe