Intraspecific and interspecific variation in floral volatiles over time

Floral volatile organic compounds (VOCs) are traits that influence plant interactions with pollinators and other species. Interspecific and intraspecific variation in traits can strongly influence community and ecosystem processes. Yet, we lack an understanding of patterns of variation in floral VOCs among individuals of a species and across species at the community-level across years, and the degree to which phylogenetic relatedness among species influences these patterns. Such an understanding is crucial to accurately interpret more complex patterns and predict consequences for pollination services and plant reproduction. We measured floral VOCs within forb populations and across forb species in a subalpine meadow in the Northern Rocky Mountains of USA over 3 years. Forb species varied in their per-flower VOC emissions as well as in the composition, originality (distance from community mean) and uniqueness (distance from nearest neighbor) of their floral VOCs. The originality of a species' floral VOCs tended to be more consistent through time than uniqueness. Although not related to phylogeny, there were species-specific differences in originality and uniqueness which may reflect responses of forbs to differences in environmental conditions among years. Interestingly, while species harbored different amounts of intraspecific variation (dispersion) in floral VOCs, species were relatively consistent in this variation across years, and there was significant phylogenetic signal in intraspecific variation. The implications of this temporal consistency for plant-pollinator interactions deserve further attention. Investigating links between interspecific and intraspecific variation in floral VOCs with pollination services and plant reproductive success will help establish the consequences of variation in this important trait.