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Research Fellows Directory

Tom Williams

Dr Tom Williams

Research Fellow


University of Bristol

Research summary

I'm interested in symbiosis as a creative force in evolution. My current work focuses on the origin of eukaryotic cells, whose constituent parts we now think originated in symbiosis between two very different prokaryotes: an archaeal host cell and a bacterial endosymbiont that gave rise to the mitochondria, or energy-producing factories, of modern eukaryotic cells. I make use of environmental sequencing and phylogenetics to identify the closest prokaryotic relatives of eukaryotes, and comparative genomics to reconstruct the cellular and genomic repertoires of their extinct ancestors. These inferences are used to constrain models for eukaryotic origins and to test hypotheses about the metabolic interactions between host and symbiont that forged their evolutionary partnership.

I'm also interested in the processes of molecular and genome evolution as construed more broadly, and in methods for reconstructing the evolutionary history of life. I've previously worked on reductive genome evolution in eukaryotic parasites and bacterial endosymbionts, and I maintain an interest in statistical methods for inferring rooted phylogenetic trees and for combining historical information from multiple sources (gene family histories, molecular clocks, changing sequence compositions) into phylogenetic analysis. There is so much to learn about the origins and early evolution of life on Earth, and with more data and better methods than ever before, I'm optimistic about future progress.

Interests and expertise (Subject groups)

Grants awarded

The prokaryotic prehistory of the eukaryotic cell

Scheme: University Research Fellowship

Dates: Oct 2015 - Oct 2020

Value: £482,881.64