Effect of local community phylogenetic structure on pollen limitation in an obligately insect-pollinated plant

Abstract

Premise of the study: Pollination is a key aspect of ecosystem function in the majority of land plant communities. It is well established that many animal-pollinated plants suffer lower seed set than they are capable of, likely because of competition for pollinators. Previously, competition for pollinator services has been shown to be most intense in communities with the greatest plant diversity. In spite of the fact that community evolutionary relations have a demonstrated impact on many ecological processes, their role in competition for pollinator services has rarely been examined. Methods: In this study, we explore relations among several aspects of the surrounding plant community, including species richness, phylodiversity, evolutionary distance from a focal species, and pollen limitation in an annual insect-pollinated plant. Key results: We did not fi nd a signifi cant effect of species richness on competition for pollination. However, consistent with a greater role for facilitation than competition, we found that a focal species occurring in communities composed of species of close relatives, especially other members of the Asteraceae, was less pollen limited than when it occurred in communities composed of more distant relatives. Conclusions: Our results demonstrate that community phylodiversity is an important correlate of pollen limitation in this system and that it has greater explanatory power than species richness alone. © 2011 Botanical Society of America.