Abstract Detail

Reproductive Processes

Ison, Jennifer [1], Hill, Lauryn [2], Incarnato, Miyauna Monique Nicole [3], Jackson, Evan [3], Johnson, Ren [3], Pearson, Avery [3], Snider, Sarah [3], Stevens, Mia [3], Zelman, Zeke [3].

Visits by a solitary specialist bee increase a prairie plant’s male fitness through siring offspring on other plants compared to visits by generalist bees.

Bees pollinate nearly 80% of flowering plants, and multiple bee species visit most of these plants. To determine how effectively a bee species pollinates, biologists often measure the per-visit seed set, pollen deposition, pollen removal, and overall visitation rate. However, quantifying how a bee visit impacts a plant’s male fitness through siring seeds on other plants has remained elusive. While some measurements, such as the ratio of per-visit pollen deposition to pollen removal, provides a proxy for siring success, the most direct method of quantifying siring success is genotyping the resulting offspring to determine the paternal plant. In this study, we combined a novel field method with paternity analysis to measure how visits by different bee taxa impact the male fitness of Echinacea angustifolia, a self-incompatible prairie plant. At our western Minnesotan study sites, Echinacea is pollinated by a diverse set of native, mostly solitary bees. While Echinacea has perfect flowers, we treated the flowering plants (n = 225) in our study as dioecious such that only one bee taxon could only visit our ‘male’ plants, while any bee taxon could visit our ‘female’ plants. We genotyped 365 offspring from the ‘female’ plants and all flowering plants at ten microsatellite loci. We identified the likely pollen donor plant for each offspring, which informed us which bee taxon successfully moved the pollen (since each ‘male’ plant was only visited by one bee taxon). We also measured the pre-visit pollen removal and deposition (n = 183) for each bee taxon. Previously we found that visits by the composite specialist bee, Andrena helianthiformis, significantly increases a plant’s per-visit female fitness compared to other bees. Our current study found that per-visit A. helianthiformis bees removed significantly more pollen but did not deposit more pollen than the other bee taxa. However, pollen depletion from the population does not seem to be the mechanism for the widely observed pollen limitation in Echinacea. Instead, the genotyping data revealed that a visit from an A. helianthiformis resulted in higher siring success on the ‘female’ plants compared to a visit by other bee taxa. Therefore, a visit by A. helianthiformis can increase an Echinacea plant’s male and female fitness. Unfortunately, this composite specialist bee appears largely absent from the smaller prairie remnants in our study area. Our work also highlights the importance of directly quantifying both female and male fitness in plants.

1 - The College Of Wooster, Biology Department, 1189 Beall Ave., Wooster, OH, 44691, United States
2 - The College Of Wooster, Biology Department,, 1189 Beall Ave., Wooster, OH, 44691, USA
3 - The College Of Wooster, Biology Department, 1189 Beall Ave., Wooster, OH, 44691, USA

Keywords:
plant-pollinator interactions
male fitness
pollination ecology
Echinacea angustifolia
Bees
tallgrass prairie
paternity
pollinator effectiveness.

Presentation Type: Oral Paper
Session: RP1, Reproductive Processes 1
Location: /
Date: Thursday, July 22nd, 2021
Time: 11:45 AM(EDT)
Number: RP1008
Abstract ID:446
Candidate for Awards:None