Plant genotype, nutrients, and G X E interactions structure floral visitor communities

Intraspecific variation in plants is driven by both genetic and environmental factors and has been shown to play an important role in determining assemblages of herbivores, predators, and pathogens. Yet, the consequences of genetic (G) and environmental (E) factors, as well as potential (G X E) interactions, for floral visitor communities remains poorly explored. In a common garden experiment, we compared the relative effects of host-plant genotype and genotypic diversity as well as soil nutrient enrichment on floral resource abundance and insect floral visitors associated with tall goldenrod, Solidago altissima. We found that the floral visitor community varied considerably among genotypes, driven predominantly by variation in floral phenology among S. altissima clones. Floral visitors also varied among nutrient treatments, though this response was much weaker than to different plant genotypes, and was likely driven by effects of floral rewards rather than of floral phenology. Importantly, we also detected several G X E interactions for both flowering and floral visitors. Taken together, our results suggest that the effects of host-plant genetic variation, and to a lesser extent G X E interactions, are key agents in structuring the diversity and composition of floral visitors.