NSF-Funded Study Explores How Mutation Rates Evolve Across Species

A team of evolutionary biologists at the University of Houston has secured nearly a million dollars from the National Science Foundation to answer a deceptively simple question: why do some organisms mutate faster than others, and what role does the way they reproduce play in that speed?

Over the next four years, Ricardo Azevedo and Rebecca Zufall, both professors at UH, will lead a collaboration with Maurine Neiman at the University of Iowa and Stephen Wright at the University of Toronto to examine how an organism's reproductive strategy—sexual, asexual, or self-pollinating—shapes the rate at which its DNA changes. The total funding across all partner institutions comes to $2.08 million. The question matters because mutation rate is essentially the speed dial on evolution itself. The faster mutations accumulate, the faster a species can adapt when its environment shifts. The slower the mutations, the more stable the organism remains.

The project builds on earlier work by Azevedo and Zufall that produced a striking finding: Tetrahymena, a microscopic single-celled organism that lives in freshwater, has the lowest mutation rate ever measured in any living thing. That discovery opened a door. If Tetrahymena mutates so slowly, what explains the variation across all other life? What determines whether one organism's DNA changes rapidly and another's barely budges?

The research design is elegant in its precision. Each institution will focus on a different organism—the UH team on Tetrahymena, the Iowa group on snails, the Toronto team on mustard plants. Within each organism, researchers will compare closely related species that differ primarily in how they reproduce. By holding other variables constant and isolating reproduction as the key difference, they can measure its exact effect on mutation rates without biological noise obscuring the signal.

Zufall described the collaboration as unusually powerful because it brings together three empiricists—scientists who work directly with living systems—and Azevedo, who builds mathematical models to interpret what the data means. "We won't only focus on the outcome of our specific species," she said. "We want to find broad patterns that underlie how populations evolve across all of life." That ambition points toward the practical stakes. Understanding how mutation rates evolve has immediate relevance to two major human challenges: cancer and antibiotic resistance.

Cancer cells inside tumors reproduce asexually, and they frequently ramp up their mutation rates as a survival strategy. More mutations mean more genetic variation, which means a better chance that some cells will develop resistance to chemotherapy or other treatments. If researchers can understand the mechanics of how and why mutation rates shift in response to reproductive mode, they gain insight into how cancer cells adapt so quickly to therapeutic pressure. The same logic applies to bacteria developing antibiotic resistance. Azevedo emphasized that the project is driven by fundamental science rather than immediate clinical solutions, but the implications ripple outward. "If we understand how mutation rates evolve, potentially we're helping understand evolution more broadly in all kinds of systems—from cancer to the evolution of antibiotic resistance or drug resistance in active infections," he said. "That's something that has a lot of practical, interesting applications." The work sits at the intersection of pure curiosity and urgent need—basic research that could reshape how medicine approaches two of its most stubborn problems.