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Microbial mediation of plant-pollinator interactions / by Robert N. Schaeffer II.

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Author	Schaeffer, Robert N.
Title	Microbial mediation of plant-pollinator interactions / by Robert N. Schaeffer II.
Date	2014
Abstract	Floral nectar of many plant species is prone to colonization by microorganisms. Their presence and metabolism have the potential to modify a suite of traits important for pollinator attraction, including nectar quality and scent. However, studies on the direct and indirect effects of nectar-inhabiting microorganisms on pollinator behavior and plant fitness remain rare. The goal of my dissertation was to fill this gap, by testing the degree to which nectar-inhabiting yeasts affect plant-pollinator interactions, plant fitness, and the mechanisms involved. To determine whether yeasts affect pollinator behavior and plant fitness, I conducted a series of manipulative experiments in the field using the cosmopolitan yeast Metschnikowia reukaufii and perennial herb Delphinium nuttallianum. Yeasts are ubiquitous in D. nuttallianum nectar and both their frequency of occurrence and abundance vary across spatial and temporal scales. Results from these experiments indicate that yeasts may enhance plant fitness, but only through the male component of reproduction, as plants treated with yeasts donated more pollen to neighboring plants. This finding suggests that yeasts affect pollinator foraging behavior given that pollen movement is a function of pollinator foraging decisions and movement in animal-pollinated systems. Further evidence supports this, as I observed that both wild and captive bumble bees responded positively to the presence of nectar yeasts in field and laboratory assays. Finally, results from my experiments highlighted the fact that male and female fitness components may not always respond similarly to environmental pressures. Traditionally, most studies that examine the consequences of interactions between plants and their environment focus only on the female component of reproduction. Considering that the majority of flowering plants are hermaphroditic, capable of achieving fitness through both male and female function, I addressed this potential bias by conducting a meta-analysis on the effects of abiotic factors and species interactions on estimates of male fitness. Male fitness varied according to interaction type and the component of male function measured. Taken together, these results highlight means by which microorganisms mediate plant-pollinator interactions and plant fitness, in addition to the importance of considering a plant's full reproductive potential when assessing interactions between it and the environment.
Description	ix, 136 leaves : ill.
Format	application/pdf
College	Dartmouth College. Department of Biological Sciences.
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D.)--Dartmouth College.
Copyright	All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means without permission in writing from the author.
DOI	http://dx.doi.org/10.1349/ddlp.1210

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