Master of Science
Way, Danielle A.
Pollination by animals is an important ecosystem service that contributes to the reproduction of many angiosperms. Climate change may alter this mutualism by affecting floral traits that are important to pollinators. Using Cucumis sativus, I tested the effects of experimentally elevated temperature and CO2 concentration on flowering onset, flower number, flower size, and floral rewards. Additionally, to better understand plant carbon balance and investment in reproduction, I measured biomass partitioning and leaf carbon fluxes of plants under their growth conditions. Carbon dynamics were similar across treatments, and plants grown under high [CO2] and temperature showed similar biomass production/allocation to control plants. Despite these similarities, both factors altered floral traits in ways that could affect plant-pollinator relationships. However, temperature effects were common, while CO2 effects were not, suggesting that studies focusing on elevated [CO2] may be less valuable than studies focusing on elevated temperature or the interaction between [CO2] and temperature.
Summary for Lay Audience
Pollination is vital for the reproduction of many plants, and by supporting plant reproduction, pollination maintains food production and wild plant communities. Due to human activities, we are experiencing factors of climate change, such as increased temperature and amounts of carbon dioxide in the atmosphere. These increases in temperature and carbon dioxide concentrations may alter the ways that pollinators interact with the plants they pollinate by changing plant traits that pollinators rely on, such as the number and size of flowers, or the amount of pollinator food plants produce. To test the effects of climate change on these plant traits, and to determine if changes in plant physiology might explain changes in plant traits, I grew cucumber plants at different carbon dioxide concentrations and temperatures. I then measured flower traits that are important to pollinators (e.g., time to flowering, number of flowers, flower size, and amount of pollinator food) and aspects of plant physiology (e.g., the amount of carbon taken up by leaves and plant size) at two different plant stages. I found that increased carbon dioxide levels and temperature altered flower traits in ways that could affect how pollinators interact with plants, but these trait changes did not seem to be related to changes in plant physiology. Warming generally had negative effects on plant traits (e.g., flowers were smaller), while higher amounts of carbon dioxide reduced the negative effects of warming on floral traits, but only at very high temperatures. Interestingly, I also found that temperature affected more traits than carbon dioxide, suggesting that warming might be more important than carbon dioxide when trying to predict how plants will respond to climate change. Furthermore, male and female flowers responded differently to the treatments, and plants at later stages tended to have lower trait values and less response to the treatments. To get a better sense of plant-pollinator interactions under future climates, studies including more plant traits, and pollinator behaviour in response to these trait changes, would be useful.
McDonald, Sarah Josina, "Floral traits and carbon dynamics of cucumber in response to climate change" (2020). Electronic Thesis and Dissertation Repository. 7294.
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