# Gene expression and functional evolution in the Drosophila female reproductive tract

> **NIH NIH F32** · UNIVERSITY OF CALIFORNIA AT DAVIS · 2023 · $69,500

## Abstract

PROJECT SUMMARY
The Drosophila female reproductive tract is morphologically and functionally complex, and as the arena where
high-stakes interactions among multiple male ejaculates and female products play out, it is also likely subject
to strong and conflicting selection pressures. Moreover, the reproductive tract is the initiation site for a cascade
of post-mating responses in female biology, from sequestering sperm and ovipositing to changes in neural
gene expression and behavior. Many of these processes may undergo sexually antagonistic selection, as
outcomes affect the sexes’ divergent reproductive interests. Nevertheless, research investment in the lower
female reproductive tract, including the sperm storage organs and the female accessory glands, severely lags
investment in male reproductive tissues. For example, the seminal receptacle, uterus, and female accessory
glands have been excluded from every major community transcriptome analysis; resources like Gal-4 drivers
or marker gene labels generally do not exist for these tissues; and the function and evolution of several organs
remain poorly described. These omissions limit insight into a range of important questions, including the
mechanisms and evolution of female-ejaculate interactions, the extent of rapid evolution in reproductive tissues
and its drivers, and the outcomes of sexual conflict. Yet these omissions also highlight an opportunity for new
low-barrier, high return investigations using well-established technologies in a leading model organism, which
this proposal pursues. First, single-cell sequencing of mated and unmated females from two diverged natural
populations will be used to 1) characterize cell-type diversity in the female reproductive tract for the first time
and 2) measure gene expression and divergence in the 5 somatic female reproductive tissues at cellular
resolution (Specific Aim 1). These data will also test the hypothesis that gene expression in female
reproductive tissues diverges rapidly owing to coevolving interactions with seminal fluid proteins. Next, genes
that are candidates for important functional evolution will be knocked out and evaluated for reproductive
effects. Specific Aim 2 tests null alleles of 7 receptors that are expressed in the seminal receptacle and show
indications of rapid divergence, to test the hypothesis that these receptors mediate female post-mating
responses. Specific Aim 3 uses a set of de novo genes with novel expression in the seminal receptacle to
explore the mysterious process of gene birth and functional integration. Specifically, the de novo gene
candidates that appear most likely to be functionally integrated based on transcript length, expression level,
structural complexity, and other metrics, will be knocked out and evaluated for effects on female reproductive
function.

## Key facts

- **NIH application ID:** 10734757
- **Project number:** 5F32GM146419-02
- **Recipient organization:** UNIVERSITY OF CALIFORNIA AT DAVIS
- **Principal Investigator:** Rachel C Thayer
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $69,500
- **Award type:** 5
- **Project period:** 2022-06-01 → 2025-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10734757

## Citation

> US National Institutes of Health, RePORTER application 10734757, Gene expression and functional evolution in the Drosophila female reproductive tract (5F32GM146419-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10734757. Licensed CC0.

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