Honors Theses

Date of Award

5-2025

Document Type

Undergraduate Thesis

Degree Name

BS

Department

Biomedical Sciences

Faculty Mentor

Jonathan Perez, Ph.D.

Advisor(s)

Jason Strickland, Ph.D. and Jeremiah Henning, Ph.D.

Abstract

Aseasonal or opportunistic breeders utilize short-term environmental cues to regulate and time reproductive efforts. Unlike seasonal breeding taxa, the mechanisms used by opportunistic breeders, such as Zebra Finches (Taeniopygia guttata), to initiate or terminate reproduction are poorly understood. Regulation of reproductive function can occur at multiple levels including the brain, pituitary, and gonads. In this project, we utilized structured water restriction to induce a non-breeding state in Zebra Finches, this induced partial gonadal regression in females, but not males. Thus, we compared the gonadal transcriptomes of breeding and non-breeding males and females to identify changes in gonadal gene expression associated with reproductive state. We identified significant changes in the expression of 22 genes in females, but only one gene in males, Steroidogenic Acute Regulatory protein (StAR). StAR plays a crucial role in regulating gonadal sex hormone synthesis. Thus, altering expression of androgens responsible for modulating reproductive behavior. The single gene regulation in males compared to multigene regulation in females possibly reflects an evolutionary adaptation to optimize reproductive success. While females must invest more to maintain a developed follicular hierarchy, maintenance of moderately sized gonads and sperm production may pose minimal cost to males. Maintaining functional gonads across breeding conditions, while modulating androgen production would help males maximize their chances of successful reproduction when conditions become favorable.

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