Bacteria are among the most abundant and diverse cellular lifeforms on Earth. The bacterial domain of life originated early in the Earth’s history, and bacterial innovations such as oxygenic photosynthesis oxidised the atmosphere and fundamentally altered the subsequent course of life’s evolution. So our understanding of bacterial evolution - how the modern groups are related to each other, the nature of their common ancestor, the timescale of bacterial diversification, and the processes of bacterial evolution - forms a major part of our understanding of the history of life on Earth as a whole. But studying bacterial evolution is challenging, both because of the deep timescales involved and because of extensive horizontal gene transfer, today and throughout their history. Gene transfer scrambles the evidence for relationships from genome data, violates the assumptions of the most commonly used phylogenetic methods, and it has sometimes been suggested that to think of bacterial history in tree-like terms is fundamentally misleading. In this talk, I will present some new methods for studying bacterial evolution that account for gene transfer, and which enable us to use much more of the available genome data to test hypotheses about bacterial evolution in deep time. I will present some recently published and new (unpublished) results on the phylogeny of Bacteria, the nature of the last bacterial common ancestor, the timescale of bacterial evolution, and the impact of the Great Oxidation Event (GOE) on bacterial genomes >2Ga.


Tom Williams is a Royal Society University Research Fellow and Associate Professor in Molecular Evolution at the University of Bristol, UK. He obtained an undergraduate degree in Genetics and a PhD in bioinformatics from Trinity College Dublin, Ireland, the latter under the supervision of Mario Fares. From 2010-2015, he worked as a postdoc with Martin Embley at Newcastle University, UK, on phylogenetic methods and the origin of eukaryotic cells. He started a research group at the University of Bristol in 2015. His work focuses on studying the early evolution of life using phylogenetic and comparative genomic methods.



About School research seminars

Seminars cover all aspects of chemistry and molecular biosciences and are delivered by visiting national and international academics. PhD completion seminars are also incorporated into the program.

Seminars are usually held in person and via zoom. All are welcome to attend.