Benefit Accrual, or the relationship between pollinator visits and seed sets

A PhD project by Christopher R Anderson of the Brosi Lab

Did you know that almost 90% of all flowering plants require an animal partner in order to reproduce?⁽¹⁾ Pollination is important for the maintenance of ecosystems important for human survival as well as agricultural food production. As such, scientists are interested in studying the intricate dynamics between plants and their pollinators. The Brosi Lab at the University of Washington, in collaboration with the UW Farm, is performing research to quantify the relationship between pollinator visits to individual flowers and resulting seed sets.

While it is widely understood that insect visitors to flowers deposit pollen that is necessary for the plant to reproduce, there are still outstanding questions around exactly how many insect visitors are necessary for a plant to decide to set a fruit and produce seeds. Furthermore, there is reason to believe that there can be too many visits and if a flower is inundated with visitors that damage floral organs that seed sets will be reduced.⁽²⁾ Is there then, a “Goldilocks” number of visits (not too many and not too few) that a flower should receive to maximize seed set? Or is the natural variation of visits to a flower sufficient in most cases? To answer these questions (and more!) we are deploying camera traps originally developed by the Crall Lab at UW-Madison to monitor all of the pollinator visits to individual flowers. Using these cameras allows us to efficiently collect complete information from multiple flowers per day – far more than we could monitor with just our eyes. We film each flower for the duration it is open and then allow the plant to set a fruit before collecting to count the seeds. Back in the lab, we process the video data using a custom-built object detection algorithm to highlight frames that have insect pollinators. Finally, armed with visitation numbers and seed counts we can begin to quantify what the relationship between visits and seeds looks like. In other words, how exactly a plant accrues benefit from individual pollinator visits. The exact shape of these curves has implications for the long-term persistence of these communities and will help scientists create more accurate models to understand how these populations change over time.

1. Ollerton, Jeff, Rachael Winfree, and Sam Tarrant. 2011. “How Many Flowering Plants Are Pollinated by Animals?” Oikos 120 (3): 321–26. https://doi.org/10.1111/j.1600-0706.2010.18644.x.
2. Morris, William F., Diego P. Vázquez, and Natacha P. Chacoff. 2010. “Benefit and Cost Curves for Typical Pollination Mutualisms.” Ecology 91 (5): 1276–85. https://doi.org/10.1890/08-2278.1.