2018 Update: Pollinators influencing male and female fitness a.k.a The Big Event

In plant populations where reproduction is mate-limited, the potential exists for selection on floral traits through both male and female function (seed production and siring success). Selection could be strong because of high variation in both male and female fitness. Additionally, most plants rely on a number of generalist insect pollinators, each of which is likely imposing selection on plant traits associated with reproduction. In many plant species, these generalist pollinators are native solitary bees. However, pollination research mainly focuses on large social bees—bumblebees and the non-native honeybee.

The main objective of this research project is to quantify how four generalist solitary bee taxa contribute to male and female fitness in the mate-limited prairie perennial, Echinacea angustifolia. To accomplish this objective, 15 researchers worked together to monitor the complete pollinator visitation in a prairie community with over 200 flowering Echinacea individuals during five days in July 2018. Through this effort, we recorded over 700 individual bee visits to a flowering Echinacea plant. To assess seed set, we removed achenes from Echinacea seedheads produced during the five observations day and xrayed the achenes for viable embryos.

Currently, we are germinating the resulting seeds and taking leaf samples. This summer, we will extract DNA from the leaf samples and genotype each sample at 11 previously optimized Echinacea-specific microsatellite loci. We will use a full paternity maximum likelihood analysis to quantify siring success mediated by the different generalist bee taxa. Our results will advance our understanding of relationships between male, female, and total fitness in plant populations. Our results will also reveal how different pollinators may cause variation in fitness. These results can help us predict the effects of changing pollinator communities for fragmented plant populations.