Date of Award:
12-2019
Document Type:
Dissertation
Degree Name:
Doctor of Philosophy (PhD)
Department:
Biology
Committee Chair(s)
Carol D. von Dohlen
Committee
Carol D. von Dohlen
Committee
Becky L. Williams
Committee
Claudia Nischwitz
Committee
Jeanette Norton
Committee
Gaelen R. Burke
Abstract
Insects form close partnerships, or symbioses, with bacteria. These partnerships allow the insects to use resources that would be unavailable to them otherwise. Certain insects, hemipterans, are able to feed on nutrient-poor plant-sap because these bacteria supplement their diets. While this association is beneficial for both the insect and bacteria, it also comes with consequences: the genomes of bacterial symbionts typically undergo extreme degradation, becoming small and lacking many genes necessary for typical bacterial functioning. In the Hemiptera, aphids, mealybugs, cicadas, true bugs, and their relatives, these bacterial partnerships tend to be stable over millions of years. However, adelgids (Aphidoidea: Adelgidae) are highly unusual in that their symbiotic bacteria have been frequently replaced. These replacements offer a unique opportunity to explore the effects of symbiont role and age on symbiont genome degradation. My dissertation uses the pattern of adelgid symbiont gains and losses to understand the process of symbiont replacements and co-symbiont gain. I accomplished this by sequencing and annotating the genomes of adelgid symbionts from across the family, first focusing on the symbionts from a pest species, then expanding to representatives from across the family, and finally conducting an in-depth exploration of how the genomes of a symbiont found in two branches of the adelgids varies between species. Through this work I demonstrate that adelgid symbionts are nutritional providers, they have a unique pattern for distributing the work of providing nutrients between the symbiont pairs, and that a symbiont’s precedence, whether it was there first or whether it joined another symbiont, has an impact on genome degradation.
Checksum
8652970cfd8e3febbb2a69790d3b1113
Recommended Citation
Weglarz, Kathryn M., "Investigating the Roles of Bacterial Endosymbionts in the Evolution of Adelgidae (Hemiptera: Sternorrhyncha)" (2019). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 7645.
https://digitalcommons.usu.edu/etd/7645
Included in
Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .