There has been tremendous interest in recent years in using both functional trait differences and phylogenetic relatedness to predict the outcomes of community assembly and species interactions. While there is considerable evidence of nonrandom patterns in many communities with respect to both functional traits and phylogenetic relatedness, recent developments have challenged many of the inferences that can be drawn from these patterns about community ecology process. In light of recent conceptual and experimental advances, I will revisit classic predictions about the relationships between phylogenetic distance, functional similarity and species coexistence, with a particular focus on exploring when we might expect these relationships to break down. Recent results from neighborhood analyses of a tropical forest community in Ecuador and a serpentine annual grassland community in California will be used as examples.
Results/Conclusions
The relationships between phylogenetic distance, trait similarity and species coexistence are expected to be strongest when a single trait with strong phylogenetic signal drives stabilizing niche differences between all species in an assemblage of interest. The relationships weaken in cases when traits can also contribute to competitive dominance between species, and especially in cases when stabilizing niche differences are driven by multiple traits, as can be seen in recent experiments in the serpentine annual plant system. Future research should aim to better connect local experimental work to the landscape-scale functional and phylogenetic patterns that have been widely documented in recent years.