Evolution is central to human disease. For example, cancer develops due to specific mutations that accumulate within a cell, while viruses such as influenza or HIV are constantly evolving in order to evade our immune system and continue infecting human hosts. Dr. Michael Desai, Associate Professor of Organismic and Evolutionary Biology at Harvard University, aims to understand how fast evolution can act and what it is capable of. By combining basic theoretical work and experimental evolution in budding yeast, he and his team develop mathematical models of evolutionary dynamics and population genetics that can be tested and verified. The goal of Dr. Desai’s research is to lay a basic foundation for understanding the role of evolution in many natural populations, including important viral and microbial pathogens.

Dr. Desai’s lab is one of the only groups working on basic questions in evolution with a combination of theoretical and experimental approaches. This has given them a unique approach to key problems. By making predictions based on mathematical models and testing them using budding yeast as a model system, Dr. Desai is providing a statistical understanding of what evolution can accomplish on a given timescale, with what probabilities. He explains, “while some fields there are technical road blocks that limit progress, in evolutionary biology we are limited only by our understanding of how to interpret the enormous influx of data that has resulted from technical advances in sequencing technology.” The task ahead of Dr. Desai and those in his field is to sift through a vast amount of sequence information from evolving populations, which has become very easy to collect, in order to understand the factors that limit how evolution can act.

Current research includes:

• How do the initial steps a population takes shape the future course of evolution? In other words, how does historical contingency affect evolutionary trajectories? Dr. Desai and his team address this question by measuring how similar or different evolution is across thousands of laboratory yeast populations with varying initial genotypes. By combining these observations with mathematical modeling, they can investigate how predictable evolution is, which has important ramifications for the evolution of microbial and viral populations, including many important pathogens.
• What role do sex and genetic exchange have on evolution? Despite the enormous effort involved in sexual versus asexual evolution, sex is ubiquitous across biology. Dr. Desai and his team are trying to uncover why sex is maintained despite its obvious costs, and to illuminate the consequences sex and genetic exchange have on evolution.