James Ferrare

Microbes engage in a minimal form of sex known horizontal gene transfer. This process can reshuffle genetic variants within a population, potentially accelerating the rate of adaptive evolution. Yet at the small rates and length scales at which it occurs, it is not well understood whether sex plays an important role in bacterial evolution.

My current research focuses on understanding the role of sex and recombination in adapting microbial populations. Like humans and animals, microbes engage in a minimal form of sex called horizontal gene transfer (HGT). During this process, one cell donates a small segment of genome to another cell, which then incorporates the segment, overwriting existing portions of its own genome. Horizontal gene transfer allows mutations to reshuffle within a population, potentially accelerating the rate of adaptive evolution. However, unlike in animals, where sex occurs every generation and involves the entire genome, HGT is extremely rare and involves only a small fraction of the genome. For example, recent estimates from bacteria in the human gut suggest the size of transferred segments could involve just one one-thousandth of the genome. Moreover, recent estimates suggest HGT occurs roughly only once every ten thousand generations. This raises a fundamental question—at these small rates and length scales, do we expect recombination to appreciably influence evolutionary dynamics in adapting populations?