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Asymmetric Density Dependence Shapes Species Abundances in a Tropical Tree Community

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Science  24 Jun 2010:
1190772
DOI: 10.1126/science.1190772

Abstract

The factors determining species commonness and rarity are poorly understood, particularly in highly diverse communities. Theory predicts that interactions with neighbors of the same (conspecific) and other (heterospecific) species can influence a species relative abundance, but empirical tests are lacking. Using a hierarchical model of survival for >30,000 seedlings of 180 tropical tree species on Barro Colorado Island, Panama, we tested whether species’ sensitivity to neighboring individuals relates to their relative abundance in the community. We found wide variation among species in the effect of conspecific, but not heterospecific, neighbors on survival, and a significant relationship between the strength of conspecific neighbor effects and species abundance. Specifically, rare species suffered more from the presence of conspecific neighbors than common species, suggesting that conspecific density dependence shapes species abundances in diverse communities.