No place for phylogeny in structuring a sandy coastal plain community

Although inference of assembly processes from phylogenetic patterns has become ubiquitous in community ecology, surprisingly few studies simultaneously test assumptions of such an approach and integrate over spatial scales and plant life stages. Here we investigate the roles of phylogeny, functional traits, and abiotic conditions in the spatial structuring of a sandy coastal plain community using data on 2800 finely mapped adult individuals and on the survival time-series of 500 seedlings. We demonstrate that phylogeny is a poor predictor of functional traits and that convergence in these traits is pervasive. In general, the community is not phylogenetically or functionally structured regardless of spatial scale. Leaf area, however, is strongly overdispersed across all spatial scales, which is generally taken as evidence of competition. We also show that seedling survival is dramatically increased when shaded by an adult, suggesting that seedlings are being facilitated. We also demonstrate species-specific effects on seedling survival that are independent of phylogeny. Overall, we show that phylogeny has very limited influence on the fine-scale assembly of that community, and that its role should always be tested instead of assumed.