Abstract
For competing species limited by one or few resources, diversity is thought to be maintained by trade‐offs that allow niche differentiation without resource partitioning. However, few studies have quantified multiple key traits for each species in a guild and shown that trade‐offs among these traits apply across the guild. Here we document strong bivariate and multivariate relationships among growth rate, fecundity, longevity, and overgrowth ability for six co‐occurring colonial invertebrates. We find that all four of these traits are constrained to a single “fast–slow” niche axis that mechanistically relates life history variation to a colonization–competition trade‐off. The location of species on this axis strongly predicts the timing of their peak abundance during succession. We also find that species closer to each other on the fast–slow axis are more likely to differ in reproductive phenology, suggesting a secondary dimension of niche differentiation for otherwise similar species.