Seminar Series – 22 Jul
Event Slider
SymbNET Online Seminar Series
Monthly seminars on host-microbe symbiosis, genomics, and metabolomics, with two talks from SymbNET researchers.
The seminars are open and free to all, but registration is required.
REGISTER
Affiliation: Genomic Microbiology, Kiel University (CAU), Germany
Title: The Darwinian fitness of extrachromosomal genetic elements
Abstract: Plasmids are an important source of raw material for microbial genome evolution outside the mainstream of bacterial chromosomes. Nonetheless, many plasmids found in nature are lacking a clear trait that is advantageous to their host; the determinants of plasmid evolutionary success in the absence of plasmid benefit to the host remain understudied. Borrowing terminology from evolutionary biology of cellular living forms, we hypothesize that Darwinian fitness is key for the plasmid evolutionary success. In the seminar I will present recent results from my group on the determinants of plasmid fitness, and how plasmid fitness might change depending on the environmental conditions. Finally, I will discuss how plasmid-centric view can help us to find general principles for the evolution of host-microbe interactions.
Affiliation: Evolutionary Biology, Instituto Gulbenkian de Ciência, Portugal
Title: Evolution in the mammalian gut
Abstract: Bacteria are known to adapt very rapidly to different selective pressure when grown in simple laboratory environments. However, we still understand little about their adaptive dynamics in natural ecosystems. Given their large population sizes 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 colonisation of a newcomer Escherichia coli strain to the gut depends on the level of microbiota diversity in this ecosystem, 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 crowded restaurant, where genomes evolve to rapidly pick an available dish and co-evolve by shuffling genes from other strains.
SymbNET Seminars