Translucent windows: how uncertainty in competitive interactions impacts detection of community pattern

Traitvariation and similarity among coexisting species can provide a window into the mechanisms that maintain their coexistence. Recent theoretical explorations suggest that competitive interactions will lead to groups, or clusters, of species with similar traits. However, theoretical predictions typically assume complete knowledge of the map between competition and measured traits. These assumptions limit the plausible application of these patterns for inferring competitive interactions in nature. Here we relax these restrictions and find that the clustering pattern is robust to contributions of unknown or unobserved nicheaxes. However, it may not be visible unless measured traitsare close proxies for nichestrategies. We conclude that patterns along single nicheaxes may reveal properties of interspecific competitionin nature, but detecting these patternsrequires naturalhistory expertise firmly tying traitsto niches.