Bacteria

Bacteria present both a major challenge and a great opportunity for evolutionary studies of biodiversity. First, they exhibit staggering levels of diversity – perhaps 10,000 species in a teaspoon of soil, most of which cannot be cultured. Second, defining species is difficult because their genetic mechanisms differ from those of the sexual animals and plants held in mind when devising theories of species and speciation. Third, they can evolve rapidly, and so offer great potential for experimental evolution. Fourth, understanding evolution in diverse bacterial systems is important for human health and understanding ecosystem responses to climate change.

Our work aims to meet these challenges. Related to our work on species and speciation, we are developing evolutionary methods for delimiting units of diversity in bacteria, and testing those methods using multi-locus sequencing of environmental isolates from the Bacillus cereus complex. Related to our work on evolution in complex systems, we are using bacterial mesocosms in the lab to investigate how evolutionary responses to environmental change are affected by species diversity, testing the predictions of our mathematical models.

We are using bacteria isolated from the tree-holes of beech trees for our laboratory mesocosms. The project is a collaboration with Dr Thomas Bell (Imperial College London). In collaboration with Dr Gemma Walton and Prof Glenn Gibson (University of Reading) and Prof. Gary Frost (Imperial College London), we also use in vitro methods to study the relationships between diversity, evolution and functioning in human gut microbes,

References

Frost G.S., Walton G.E., Swann J.R., Psichas A., Costabile A., Johnson L.P., Sponheimer M., Gibson G.R., Barraclough T.G.  2014. Impacts of plant-based foods in ancestral hominin diets on the metabolism and function of gut microbiota in vitro. mBio. 5: e00853-14

Fiegna, F., Moreno-Letelier, A., Bell, T., Barraclough, T.G. Online Early. Evolution of species interactions determines microbial community functioning in new environments. ISME J. doi:10.1038/ismej.2014.215

Lawrence, D., Fiegna F., Behrends, V., Bundy, J.G., Phillimore, A.B., Bell, T. and Barraclough T.G. 2012. Species interactions alter evolutionary responses to a novel environment. PLoS Biology 10: e1001330.

Perron, G.G., Lee, A.E.G., Wang, Y., Huang, W.E., Barraclough T.G. 2012. Bacterial recombination promotes the evolution of multidrug-resistance in functionally diverse populations. Proc. R. Soc. Lond. B.279:1477-1484.

Barraclough, T.G., Hughes, M., Ashford-Hodges, N., and Fujisawa, T. 2009. Inferring evolutionarily significant units of bacterial diversity from broad environmental surveys of single-locus data. Biology Letters 5: 425-428.

Purcell, D., Sompong, U., Yim, L.C., Barraclough, T.G., Peerapornpisal, Y. and Pointing, S.B. 2007. The effects of temperature, pH and sulphide on community structure of hyperthermophilic streamers in hot springs of northern Thailand. FEMS Microbiology Ecology. 60: 456-466.