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Investigating the origination and evolution of a morphological novelty in Drosophila genitalia

Shodja, Donya N (2022) Investigating the origination and evolution of a morphological novelty in Drosophila genitalia. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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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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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Shodja, Donya Ndns37@pitt.edudn370000-0001-9284-1648
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee MemberArndt, Karenarndt@pitt.eduardnt
Committee MemberGerard, Campbellcamp@pitt.educamp
Committee MemberLance, Davidsonlad43@pitt.edulad43
Committee MemberMiler, Leemiler@pitt.edumiler
Committee ChairMark, Rebeizrebeiz@pitt.edurebeiz
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


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