Plant-pollinator interactions in the face of global change




O'Connell, Megan, Ph.D.

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More than 80% of terrestrial plant species are dependent on animal pollinators to facilitate their reproduction and survival via pollen dispersal and pollen-mediated gene flow. With anthropogenic habitat destruction, urbanization, and climate change intensifying, the alteration and loss of pollination services may be one of the greatest threats global biodiversity faces today. Plant-pollinator interactions meet a myriad of synergistic challenges, both spatial and temporal, that impact their frequency and efficacy, ultimately altering the movement of pollen-mediated genetic diversity across landscapes and rendering tangible consequences for plant reproduction. Therefore, the ability for ecosystems to support diverse and robust pollinator communities, that can facilitate sufficient pollination services in quickly changing landscapes, may largely determine the future genetic health and survival of plant communities. The spatial impacts of land-use change and urbanization alter both density-dependent dispersal patterns and pollinator foraging behavior, while climate change may exacerbate these issues by further altering floral resource availability and foraging behavior temporally. To explore these dynamics we conducted extensive field surveys (Chapters 1, 2, 3), molecular analyses (Chapters 1, 2), and pollen analyses (Chapters 2, 3) across two systems: the tropical lowland forests of the Panama Canal region (Chapters 1, 2) and a network of urban gardens along the central coast of California (Chapter 3). We explored the scales at which pollen dispersal and pollen-mediated gene flow can be influence by deforestation (Chapter 1), finding measurable fine-scale effects in a multipaternal tropical tree species. We then added a temporal aspect to our tropical study system to explore how density-dependence may interact with climate change to impact pollination services after a plant-pollinator network experienced a discrete phenological shift (Chapter 2), finding that the distribution of genetic diversity and the robustness of plant-pollinator networks may play important roles in buffering plants from the negative effects of climatic extremes. We also investigated how the most extreme form of habitat degradation, urbanization, impacts pollinator foraging preferences across a network of urban gardens (Chapter 3), finding clear patterns of how pollinators utilize resource patches within cities as a function of the surrounding urban matrix and the richness of plant communities in these patches. Lastly, I present a portfolio of professional science media products I produced and/or co-produced throughout the course of my dissertation studies (Chapter 4), illustrating the importance of science communication for the fields of ecology and conservation, and the potential ways researchers can participate in the creation of compelling science media products.



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