Shodja, Donya N
(2022)
Investigating the origination and evolution of a morphological novelty in Drosophila genitalia.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The origination of new morphological structures has been one of the most fascinating problems in the field of evolutionary developmental biology. Like any anatomical feature, morphological novelties are controlled by unique developmental programs. In particular, developmental signaling pathways that are conserved throughout an organism’s development and are responsible for specifying fields of cellular identities have been frequently implicated in the evolution of novelties. Yet, we lack a solid understanding of the evolutionary history of the signaling centers associated with novelties. Namely, what roles did they have prior to the appearance of the novelty, and how did their novel activities emerge? Here, I examine the evolutionary origins of a morphological novelty. Utilizing a newly evolved complex morphology in an organism possessing an arsenal of genetic tools, I investigate 1) the regulation of a signaling center associated with the development of a novelty 2) the pre-existing roles of the novelty-associated signaling center, and 3) how this signaling center exerts its downstream effects. Specifically, I investigated the origin of the posterior lobe, a recently evolved cuticular projection on male fruit fly genitalia unique to the Drosophila melanogaster clade. During posterior lobe development, Delta, a ligand of the Notch signaling pathway, is expressed in a spatially expanded pattern which is essential for posterior lobe development. I explored the posterior lobe associated regulation of Delta and discovered that this signaling center becomes active days before its involvement in posterior lobe development. I identified an early-acting role essential for genital development— the eversion of the genital disc. I then examined the mechanism by which Delta orchestrates this conserved process, and determined a role for the apical extracellular matrix (aECM) protein Dumpy in genital disc eversion. This work demonstrates that complex morphological novelties may develop from pre-existing programs in the context of already intricate developmental processes, emphasizing the importance of uncovering the ancestral roles of genetic programs associated with novelties. Furthermore, through discovering an ancestral role for this signaling center, I uncovered a critical function for Notch signaling in genital disc eversion, contributing to our understanding of this convoluted and vital process for Drosophila genital development.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
12 October 2022 |
| Date Type: |
Publication |
| Defense Date: |
12 July 2022 |
| Approval Date: |
12 October 2022 |
| Submission Date: |
26 July 2022 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
118 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Biological Sciences |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
morphological novelty, signaling center, posterior lobe, enhancer, eversion |
| Date Deposited: |
12 Oct 2022 16:26 |
| Last Modified: |
12 Oct 2022 16:26 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/43369 |
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