Evolution@Vanderbilt

Ashlynn joined the CoEvoD program as a third-year ESI CoEvoD fellow in 2025.

Ashlynn combines computational and experimental approaches to investigate fundamental questions in microbial evolution. She has thus examined two Escherichia coli genes (acrB and ompF) that repeatedly acquire mutations under repeated resource limitation and, in turn, alter antimicrobial susceptibility. Fitness assays revealed a reciprocal-sign epistatic interaction: only the double mutant gained benefits across both growth and survival phases. This work revealed a genetic architecture linking adaptation to nutrient stress with antimicrobial susceptibility, while also underscoring the rugged nature of microbial fitness landscapes. Her current work focuses on the bacterial stringent response—a regulatory program well studied in acute stress but poorly understood in the context of chronic stress and long-term evolution. She aims to determine how evolved mutations in key stringent response genes shape bacterial adaptation and influence reservoirs of disease.