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June 2, 2021

10am Zoom Webinar

Isabel Gordo
Instituto Gulbenkian de Ciência

" Two Modes of Evolution Shape Diversity of a Common Gut Commensal "

Gut bacteria are important modulators of the health of their hosts. Given the large population sizes that any bacterial species can achieve when colonising the intestine, commensals have a tremendous potential for rapid evolutionary change in short time scales. By performing experimental evolution in vivo we find that the successful colonization  of an Escherichia coli strain depends on the level of microbiota diversity, and its mode of evolution on the presence of a closely related resident strain. Tracking the emergence of de novo mutations and their trajectories reveals two distinct modes of E. coli adaptation to the gut: one characterised by the coexistence of emerging ecotypes, another by recurrent selective sweeps and horizontal gene transfer events. Our results show that genes, phages and plasmids can be gained and lost on time scales of hundreds of generations. They further show the readiness with which strains of E. coli can retain and domesticate newly arriving mobile genetic elements which can carry simultaneous benefits and costs. The observed pattern of metabolic evolution lends support to the hypothesis that the gut is a crowed restaurant, where genomes evolve to rapidly pick an available dish and co-evolve by shuffling genes from other strains.

Via Zoom Webinar

Host: Nandita Garud