Rachel Thayer to Speak on Drosophila Sperm Storage

Postdoctoral fellow Rachel Thayer of the lab of UC Davis Distinguished Professor David Begun, Department of Evolution and Ecology, will present the next UC Davis Department of Entomology and Nematology seminar.

Thayer will speak on "Evolutionary Genomics of the Drosophila Sperm Storage System" at 12:10 p.m., Wednesday, Oct. 14 in 122 Briggs Hall. Her presentation also will be on Zoom. The Zoom link: https://ucdavis.zoom.us/j/95882849672

"Sexual selection drives extreme traits and coevolution, especially in reproductive tissues," Thayer writes in her abstract. "Seminal fluid proteins in Drosophila are an iconic case study for post-copulatory sexual selection. A leading explanation for these sexually transferred proteins’ rapid adaptation is their potential to manipulate female physiology to advance male fitness, generating long-term sexual conflict. However, this co-evolutionary model requires counter-evolution in females, which we sought to find by characterizing gene expression evolution in the female tissues that contact seminal fluid (i.e. the uterus, sperm storage organs, female glands). Instead, we found surprises that challenge the prevailing model and highlight the necessity of greater nuance and female inclusion to understand both physiology and molecular evolution."

"First, we found that females themselves express more than 45 percent of the genes previously believed to encode male-limited seminal fluid proteins, primarily inside their sperm storage organs," she noted. "This result immediately complicates the idea that manipulating females is the salient function of SFPs, suggesting instead that females use these proteins in secreted fluids that support spermatozoa, and that selection on these genes may also occur in females. Next, I share progress on re-evaluating the molecular evolution of these proteins by incorporating female variation across the levels of protein sequence, inter-population differences, and macroevolutionary contrasts. Because female sperm storage is pervasive in insects, these co-evolutionary dynamics may be broadly representative."

Thayer describes herself "an evolutionary and developmental geneticist studying insects." She is currently studying "functional evolution in the insect female reproductive tract as a National Institutes of Heatlh K99 Pathway to Independence Research Scholar at UC Davis," mentored by  David Begun. 

Doctorate from UC Berkeley

Thayer completed her doctoral research on the biophysics, evolution, development, and genetic regulation of iridescent nanostructures on butterfly wings in Nipam Patel's lab at UC Berkeley in 2020.

"I enjoy relating evolutionary outcomes across timescales, from rapid artificial selection through population level variation and macroevolutionary differences among species. To leverage millions of years of naturally evolved ‘experiments’ that have explored life’s available possibility space, I work to integrate experiments in non-model insect species that evolved extreme anatomy and physiology alongside incisive genetic dissection in the model species Drosophila melanogaster."

For any Zoom or technical issues, contact seminar coordinator Lisa Baik at [email protected].

Resources:

• "Invisible Anatomy in the Fruit Fly Uterus," UC Davis College of Biological Sciences, Oct. 25, 2024
• "ECR Spotlight: Rachel Thayer," Journal of Biologists, 2023