Degree Name
PhD (Doctor of Philosophy)
Program
Biomedical Sciences
Date of Award
8-2025
Committee Chair or Co-Chairs
Gerardo Arceo-Gómez
Committee Members
Thomas Jones, Carlos Martel, Darrell Moore, Melissa Whitaker
Abstract
Microbial communities inhabiting floral nectar, known as the nectar microbiome, are important mediators of plant-pollinator interactions. However, the ecological and environmental factors that shape the composition of these microbial communities remain poorly understood. While previous studies have examined the effects of a few microbial groups, typically independent of one another, on one plant or pollinator species, this dissertation takes a wide-scale approach to explore how abiotic conditions and biotic interaction’s structure microbial communities within floral nectar. Furthermore, I also quantify how variation in microbial richness and identity influences pollinator behavior and plant reproductive success.
This dissertation shows that microbial abundance and richness are strongly influenced by environmental conditions and anthropogenic effects, particularly temperature and landscape urbanization. Furthermore, network analyses of a diverse plant community reveal that the structure of plant-microbe interactions was uncoupled from that of plant-pollinator interactions, suggesting their assembly is mediated by different ecological processes. By linking plant-microbe network properties with plant fitness components this study also revealed that plants with higher microbial network centrality, that is plants that act as microbial hubs, experience reduced pollen tube formation, suggesting fitness costs of increasing microbial species richness. Finally, in the last chapter of this study I used an experimental approach to show that changes in microbial richness alone can alter pollinator visitation frequency and duration. Together, these results demonstrate that the nectar microbiome can be shaped by multiple biotic and abiotic drivers at large spatial scales and can act as both as a determinant of plant-pollinator dynamics, with significant consequences for interaction networks and plant fitness.
Document Type
Dissertation - embargo
Recommended Citation
Barker, Daniel A., "Drivers and Consequences of Changes in Nectar Microbiome Composition Across Spatial and Biological Scales" (2025). Electronic Theses and Dissertations. Paper 4582. https://dc.etsu.edu/etd/4582
Copyright
Copyright by the authors.
Included in
Behavior and Ethology Commons, Other Ecology and Evolutionary Biology Commons, Population Biology Commons
