Abstract

Too Close to Home? Why are some species common while others are exceedingly rare? Attempts to answer this question have met limited success, particularly in hyperdiverse communities, such as tropical forests. Comita et al. (p. 330 , published online 24 June; see the cover) reveal a previously overlooked explanation. A large data set on seedling dynamics of 180 tree species on Barro Colorado Island, Panama, combined with Bayesian statistical techniques, revealed that species abundance is shaped by the degree to which species negatively impact their own regeneration. Rare species regenerated far less well than common species in the proximity of conspecific neighbors, suggesting a mechanism determining the relative abundances of tree species in highly diverse tropical forest communities.