Community phenology and its consequences for plant-pollinator interactions and pollen limitation in a vernal pool plant

Premise of research. Pollen limitation may affect the potential for plants to set a full complement of seeds, persist in a community, and influence floral evolution. The level of pollen limitation experienced by a population may be influenced by the phenology of the pollinator and coflowering plant community. Methodology. In this study, I used pollen supplementation to test for pollen limitation throughout a season in a population of insect-pollinated, vernal pool annuals, Limnanthes douglasii rosea. I collected information on the phenological changes in pollinator-sharing, coflowering community members and pollinator community composition in three flowering seasons to investigate the potential impacts of community composition on pollen limitation. Last, I investigated components of pollen transfer that may impact pollen limitation: pollen loads found on pollinator bodies and pollen found on stigmatic surfaces after visitation. Pivotal results. I found that L. d. rosea experiences significant pollen limitation during the early season when evaluated over the entire flowering season and that the level of pollen limitation is related to changes in the coflowering community and changes in the pollinator community. The effects of coflowering community and pollinator community composition are also correlated with seasonality. Both components of pollen transfer are positively associated with greater abundances of L. d. rosea and coflowering community member Lasthenia spp. Conclusions. This study demonstrates that pollen limitation can change throughout a season and that pollen limitation and factors that affect the extent of pollen limitation are influenced by community context.