Pollination alters floral longevity of Arctic lupine
Clara Reid, Department of Biology and School of Environmental Studies This research was supported by the Jamie Cassels Undergraduate Research Awards, University of Victoria Supervised by Dr. Brian Starzomski, School of Environmental Studies March 6, 2019Results
Methods
Discussion
• Understanding pollination ecology is necessary for maintaining healthy
natural ecosystems and agricultural crops.
• Insect-pollination is a mutualistic
relationship in which a flower receive pollen necessary to produce seeds, and the insect gets a nutritious reward such as nectar. Therefore, pollination affects the health of plants and pollinators.
• Floral longevity is the period of time an individual flower blooms for, from the first time it opens to when the petals wilt, fall off or close for the last time1. Insects pollinate flowers during this period, so floral longevity affects
pollinator activity.
• In some species, pollination can alter
floral longevity1. This process affects the efficiency of plant-pollinator
interactions2.
• This study investigated whether insect pollination affects
the length of floral longevity in Arctic lupine (Lupinus
arcticus), an ecologically-important boreal forest species.
Objective
Introduction
Study site and date
• Boreal forest near Whitehorse, Yukon during June and July of 2018. Study design
• 34 Arctic lupine plants were each subject to the three pollination treatments:
Bumblebees (Bombus spp.) and other bee taxa were observed pollinating Arctic lupines at the study site, confirming that
flowers in the open-pollination treatment were being insect-pollinated.
Figure 2. The average percent fruit set (% of flowers that
produced seeds) was
significantly lower for bagged flowers than hand and
open-pollinated flowers. High % fruit set indicates high success of
pollination. This figure shows the average and standard error of % fruit set for the three
pollination manipulations. Figure 1. Average floral
longevity was significantly
longer for bagged flowers than hand and open-pollinated
flowers. This figure shows the average and standard error of floral longevities, in days, for the three pollination
manipulations.
I would like to thank my directed studies supervisor Dr. Brian Starzomski for guidance throughout this study, Maria Leung for help developing the research question and
the Jamie Cassels Undergraduate Research Award for funding this project.
1. van Doorn, W. G. (1997). Effects of pollination on floral attraction and longevity. Journal of Experimental Botany, 48(314), 1615-1622.
2. Schaal, B. A., & Leverich, W. J. (1980). Pollination and banner markings in Lupinus texensis (Leguminosae). The Southwestern Naturalist, 25(2), 280-282.
3. Pieper, S. J., Loewen, V., Gill, M., & Johnstone, J. F. (2011). Plant responses to natural and experimental variations in temperature in alpine tundra, southern Yukon, Canada. Arctic,
Antarctic, and Alpine Research, 43(3), 442-456.
4. Forrest, J. R. K. (2015). Plant-pollinator interactions and phenological change: What can we learn about climate impacts from experiments and observations? Oikos, 124, 4-13. 5. Proctor, H. C., & Harder, L. D. (1995). Effect of pollination success on floral longevity in the orchid Calypso bulbosa (Orchidaceae). American Journal of Botany, 82(9), 1131-1136.
• Since pollination-induced reduction of floral longevity is an adaptation to increase plant efficiency, this study suggests
that Arctic lupines may be limited by resources or pollinators. This could be due to the study region’s cold climate which
limits pollinator activity and plant growth, as Arctic lupines have been shown to produce more flowering stems in
artificially-warmed conditions3.
Clara Reid, University of Victoria
• Floral longevity of Arctic lupine flowers was shortened by
successful pollination, namely insect pollination and
cross-pollination by hand.
• Pollination-induced shortening of floral longevity helps plants
and pollinators conserve energy. For plants, the effect reduces
energy spent maintaining
blooming flowers which have
already been pollinated and thus are likely to produce seeds1. For pollinators, flowers closing or
1. Bagged: A mesh pollinator-exclusion bag was put over the flowering stem to
prevent insects from accessing the flowers. 2. Cross-pollination by hand: Flowering stems were bagged as in 1. As they
bloomed, flowers were hand-pollinated using pollen from another Arctic lupine.
3. Open-pollination: Not manipulated, flowers accessible to pollinating insects.
References
wilting soon after being pollinated means less time and energy is spent visiting flowers whose rewards are
depleted2 (ie. whose pollen or nectar has been removed by previous insects).
Boreal forest ecosystem. Plants and pollinators in this ecosystem may experience resource limitation and phenological mismatch.
Photo by Clara Reid, 2013
• This study’s findings help us understand plant-pollinator phenological mismatch – a lack of
temporal overlap between flowers blooming and their pollinators being active. As species adapt
independently to climate change, phenological mismatch is becoming more common4, yet
pollination-mediated floral longevity could decrease this mismatch. Further investigations of Arctic lupine pollinators and factors affecting their health and
activity would be beneficial.
Photo by Clara Reid, 2018
Acknowledgements
Photo by Clara Reid, 2018
Photo by Clara Reid, 2018 Photo by Robby Deans, 2017, used with permission
https://www.inaturalist.org/observations/5127404 Photo by Jonathan Schnurr, 2018, used with permission https://www.inaturalist.org/observations/19267083
Photo by David Inouye, 2019, used with permission
https://www.fs.fed.us/wildflowers/pollinators/pollinator-of-the-month/bumblebees.shtml
Top: Fairy-slipper Orchid (Calypso
bulbosa)
Bottom: Foxglove (Digitalis sp.) These species exhibit pollination-induced shortening of floral
longevity1,5.
Above: Arctic lupine plant with pollinator-exclusion bags on several flowering stems.
Right: Flowering stem of Arctic lupine with blooming and wilted flowers and pods containing seeds.
Floral Longevity
Insect Pollinators
Percent Fruit Set
Yellow-fronted Bumblebee (Bombus flavifrons) on a lupine (Lupinus sp.) flower.
Observations
• The floral longevity (# of days a flower
bloomed) was recorded for individual flowers. • The number of flowers that produced seeds
was counted to determine if flowers had been successfully pollinated.
• While Arctic lupines were blooming, pollinating insects seen on the flowers or heard at the study site were noted.
Arctic lupine
