An interview with Anna Dewar

October 2020

Anna Dewar is a PhD student in the Department of Zoology at the University of Oxford, and a member of the Microbiology Society. In this interview, she discusses her research on bacterial cooperation and horizontal gene transfer and tells us why she thinks microbiology matters.

Anna Dewar
© Anna Dewar

Tell us about your research.

I am interested in the evolution of social behaviour, and specifically cooperation. While this may seem strange for a microbiologist, bacteria actually have remarkably active social lives – although they may be a little different from yours or mine. 

Bacteria secrete a range of extracellular molecules, which allow them to access nutrients, invade hosts, and clump to form biofilms. The benefits of these molecules are shared with all surrounding cells and have evolved because of these shared benefits; their production is therefore a form of cooperation. Genes for cooperative behaviours which provide no direct benefit to the actor are expected to spread if individuals direct these behaviours towards others that also carry the cooperative genes, such as close relatives. For example, some bird species, where individuals providing help at others’ nests preferentially help relatives. However, explaining how cooperation evolves and spreads in bacteria becomes more complex; bacterial genes transfer not just vertically to descendants, but horizontally to other cells, even to distant lineages. 

Instead of evolutionary trees, the history of bacterial genes can appear more like a dense web. This has implications for what we consider to be relatives within bacteria. My research is to identify how horizontal gene transfer in bacteria impacts the evolution of cooperation, and whether this kind of gene transfer helps, or hinders its stability. I am using a combination of bioinformatics, theory and experiments to ask whether cooperative genes are expected to transfer more or less horizontally than non-cooperative genes, and the consequences this may have for the structure of bacterial genomes. 

Why is this research important? 

Many of the behaviours mentioned above have implications for our health, such as biofilms which can help bacteria to establish infections, and secreted molecules which allow bacteria to access scarce and growth-limiting nutrients during an infection. Furthermore, horizontal gene transfer can lead to the rapid spread of traits, such as antibiotic resistance; a problem which has potentially devastating implications for public health. Understanding the impact of this transfer on bacterial interactions is fundamental research and will help to discover more about the role of these microscopic organisms in our lives. 

What qualifications did you obtain before starting this role? 

Before starting my PhD, I studied for a bachelor’s degree in Biology. Having been particularly interested in evolution during school, my university course further sparked my fascination in the subject. My PhD program is the Interdisciplinary Bioscience Doctoral Training Program here in Oxford. The training modules and opportunity to carry out rotation projects encouraged me to seek an interdisciplinary approach to studying evolution, which comes naturally when working with bacteria. 

Where did your interest in microbiology come from? 

While studying the evolution of cooperation in university, I was amazed to learn that many ideas and theory developed for animals can be applied to bacteria. However, how well this theory actually applies is currently under debate and is something I am excited to help solve. The knowledge that bacteria are so much more dynamic than many people assume, combined with how much we still don’t know about how microbes interact, makes working in microbiology fast-moving and exciting. As I have become more familiar with the biology of microbes, I have become increasingly interested in multiple areas of microbiology outside of my initial interests. The more I learn about microbes, the more they amaze me. 

Why does microbiology matter? 

We are only beginning to realise the scale of the impact microbes have on our lives. We each carry millions of them, the vast majority harmless, or even beneficial to our health. However, microbes are also implicit in many infections and diseases. It is therefore crucial that we understand how microbial populations interact with each other, and how this affects whether they help or harm us. More generally, investigating how and why life works the way it does is fundamental to scientific research, and particularly true for the staggering and often overlooked diversity of microbial life. 

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