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School of Biological and Behavioural Sciences

Exploring the impact of plant genome size on community structure dependent on soils and underlying geology

Supervisors: Professor Andrew Leitch (QMUL), Dr Ilia Leitch (Royal Botanic Gardens Kew)

Project description

The amount of DNA in the nucleus of a cell – known as genome size (GS) - varies c. 2,400-fold in angiosperms representing the largest range for any comparable group of organisms. Much has been written about the consequences of this huge diversity, with studies showing that GS constrains both size and rate-related traits and hence the range of ecological conditions in which a plant can grow (Greilhuber and Leitch 2013). 

Our recent studies on experimental grassland plots suggest that interactions between nitrogen (N) and phosphorous (P) availability in the environment and GS can influence species distributions and plant community composition (Guignard et al. 2016). For example, our analysis of the Park Grass Experimental plots at Rothamsted showed that the biomass-weighted mean GS of species growing on plots receiving both N and P fertilizer were significantly higher than those of plants from plots receiving either no nutrients or just N or P. These findings were supported by using phylogenetically-informed modelling approaches (i.e. MCMCGLMM) which uncovered significant three way interactions among GS, N and P. In part this may be because genomes are expensive to build and maintain in terms of N and P, as DNA and RNA are amongst the most N and P demanding biomolecules of the cell (Guignard et al., 2016). 

Nevertheless, the extent to which these findings from grasslands can be applied to other ecosystems is currently unknown. This project aims to address this knowledge gap by extending our studies to the landscape level to see how the dynamic interactions between N, P and GS are influenced by contrasting underlying geologies, soil types, soil ages and farming practices across the diverse landscapes of the UK, each of which may each have their own N and P and GS interaction dynamics. 

This is an ecology project jointly superivsed by Royal Botanic Gardens, Kew and Queen Mary University of London that will explore genome size as a new dimension in plant community ecology. 

This project tests the hypothesis that availability of N and P across the UK landscape influences the distribution of species based on their GS. It is predicted to generate new insights into how macronutrient availability in the environment interacts with GS to shape the biodiversity and ecology of the UK flora. 

The interdisciplinary nature of this PhD project combines the scientific expertise, datasets, and facilities available at Queen Mary, University of London and the Royal Botanic Gardens, Kew and will ensure you receive comprehensive training, hence developing your skills in, for example, field work, remote sensing, ecological statistics and nutrient stoichiometry. 

Eligibility and applying

Applications are invited from candidates with, or expecting to be awarded, at least an upper-second class degree in an area relevant to the project. International students are required to provide evidence of their proficiency in English language skills. 

For informal enquires please contact Professor Andrew Leitch (


  • Guignard, M. S., Nichols, R. A., Knell, R. J., Macdonald, A., Romila, C.-A., Trimmer, M., Leitch, I. J. and Leitch, A. R. (2016). Genome size and ploidy influence angiosperm species’ biomass under nitrogen and phosphorus limitation. New Phytol. 210: 1195–1206. doi:10.1111/nph.13881 
  • Greilhuber, J., Leitch, I.J. (2013) Genome size and the phenotype. In: Leitch IJ, Greilhuber J, Doležel J, Wendel JF eds. Plant genome diversity, vol 2, Physical structure, behaviour and evolution of plant genomes. Wien: Springer-Verlag, 323-344. doi: 10.1007/978-3-7091-1160-4_20

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