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Meeting ID: 928 6638 6088

Passcode: 326366

The human gut microbiome is comprised of a complex ecosystem of microbes that reside inside of us and play an important role in our health. With as many as a billion new mutations entering our microbiomes per day, bacterial genomes inside us have a great opportunity to evolve rapidly, unlike our own genomes, which change very little throughout our lifetimes. For us humans, this genetic dynamism is both an opportunity (e.g., enabling digestion of new foods) and a challenge (e.g. the evolution of drug resistance). Despite the potential importance of these effects, we currently know very little about if and how bacteria living in us evolve. I will present our recent work quantifying the evolutionary dynamics of ~40 prevalent species of gut bacteria in adults and infants. We find evidence that indeed commensal gut bacteria can evolve in healthy hosts on 6 month timescales. Moreover, we find that rates of evolution are significantly more rapid in infants compared to adults. Finally, over our lifetimes, resident bacteria are typically replaced by distantly related strains, suggesting that even though gut bacteria can evolve on human-relevant timescales, there are limits to the extent of local adaptation.