Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Biology

Date of Defense

8-24-2023

Graduate Advisor

Nathan Muchhala, Ph.D.

Committee

Aimee Dunlap, Ph.D.

Robert Marquis, Ph.D.

Sara Miller, Ph.D.

Matthew Betts, Ph.D.

Abstract

Land use change is a major driver of biodiversity loss and consequently has led to the loss of genetic diversity in many plant populations due to declines in population sizes and an increase in spatial isolation. However, not all plant populations respond similarly to land-use change, suggesting there are additional mechanisms mediating plant population genetic patterns. Here, I examine the role of pollinators as this mediating factor. In Chapter 1 I conducted a meta-analysis to investigate how different types of pollinators drive changes in gene flow for plant populations in disturbed habitats, finding that different types of pollinators mediate different levels of genetic connectivity in plant populations and that pollinators like large bees are tolerant of disturbance, maintaining equal levels of gene flow in undisturbed and disturbed habitats. In Chapter 2 I studied the relationship between landscape and habitat characteristics, pollinator community, and plant mating quality using the generalist pollination system of Campanula americana. I found that different types of pollinators respond to different aspects of the environment and differentially affect mating quality. In Chapter 3 I investigated the consequences of differences between pollinators in their pollen deposition patterns. I tested if pollination by multiple donors selects for offspring with higher fitness in Allium stellatum and found that pollen loads with a greater number of donors increased female reproductive success at the expense of slower growing seedlings. This dissertation has illuminated the intricate role pollinators play in influencing plant population dynamics and their importance in plant conservation.

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