Floral trait evolution: Insights from bee-pollinated Penstemon to maternal effects in Brassica rapa
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Date
2024-12
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University of New Brunswick
Abstract
My thesis explores the evolution of floral traits in angiosperms, focusing on phenotypic selection and maternal effects. Floral traits are influenced by both pollinators and abiotic factors, making it essential to study how these multiple selection agents shape various traits related to attraction, efficiency, and less-explored reward traits like nectar and pollen.
Chapter 1 examines phenotypic selection in two bee-pollinated Penstemon species, analyzing 15 traits related to size, visual signals, pollinator fit, and rewards. Despite floral similarities, each species experienced different selection pressures, underlining the need to measure multiple functional traits to fully understand evolutionary dynamics.
Chapter 2 explores how climate change-induced drought affects floral traits and pollinator interactions in Brassica rapa. A common garden experiment showed that drought reduced most floral traits except nectar concentration, which increased. Larger flowers were favored in drought conditions highlighting the context-dependent nature of maternal effects. While pollen limitation wasn't observed, water availability altered selection on plant height.
Chapter 3 investigates how maternal effects and plasticity influence floral traits in Brassica rapa under different water conditions. Maternal drought stress significantly impacted offspring traits related to pollinator attraction and efficiency, particularly under continued drought. This highlights the importance of considering both maternal effects and environmental context in predicting plant responses to climate change.
Overall, my work emphasizes the need for integrating studies on maternal effects and phenotypic selection to better understand how plants adapt to environmental stressors, enhancing knowledge of the evolutionary processes driving floral diversity and plant fitness.