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Too Much Of A Good Thing: How Does Waterlogging Constrain Species Distributions?

Supervisors: Andrew Tanentzap (Primary Supervisor), Howard Griffiths and Julian Hibberd

Reference code: B139

Importance of the area of research:  Trees provided habitat for much of the world’s biodiversity and deliver vital ecological services.  Identifying mechanisms underlying tree mortality and predicting how these might respond to future stressors is therefore important.  Mortality may be particularly sensitive to waterlogging, especially in north temperate regions, which are predicted to become wetter.  Research in our group is showing that physiological traits of disparate plant families change predictably along waterlogging gradients and that their evolution along molecular phylogenies explains subsequent species distributions.  Our aim is now to use Populus as a model organism for linking trait evolution and ecological dynamics with underlying molecular mechanisms (Brunner et al. 2004).  Populus is ideal for such purposes because species are widely-distributed across broad environmental gradients. 

What the project will involve:  We will test whether waterlogging tolerance has evolved differently across multiple tree genera and thereby explains species distributions.  We will run a large glasshouse experiment with many tree species (e.g. Populus, Betula, Pinus) grown under different watering regimes.  We will record mortality in relation to photosynthesis, stomatal conductance, and root anoxia.  We will then try to identify molecular mechanisms accompanying physiological responses to waterlogging and use these to explain macro-ecological patterns.

What the student will do:  The student will execute the experiment and collect physiological data.  Using published databases, they will also collate species distribution data for focal plant species and corresponding climate and soil maps.  They will estimate levels of waterlogging associated with species distributions and use statistical models to test whether these increase with experimental-derived tolerances.  Molecular phylogenies will also be estimated for taxa to reconstruct the evolution of waterlogging tolerance in relation to biogeography and test whether trait evolution explains historical ranges (e.g. Bocxlaer et al. 2010).  Finally, we will try to measure expression of genes implicated in waterlogging tolerance (Le Provost et al. 2012), to also test their evolution across lineages.

Training that will be provided:  The student will be given training in measuring whole plant physiology, experimental design, and statistical modeling (including phylogenetic methods and computer programming).  Training in molecular biology techniques will be provided where necessary, but some skills in DNA extraction, qPCR, and bioinformatics are ideal.  Partly, this project would suit a molecular biologist interested in working at the forefront of ecological research. 


  1. Brunner, A.M. et al. 2004. Poplar genome sequence: functional genomics in an ecologically dominant plant species. TRENDS in Plant Science, vol. 9, pp.49-56.
  2. Le Provost, G. et al. 2012. Role of waterlogging-responsive genes in shaping interspecific differentiation between two sympatric oak species.  Tree Physiology, vol 32, pp.119–134.
  3. Van Bocxlaer, I. et al. 2010. Gradual adaptation toward a range-expansion phenotype initiated the global radiation of toads. Science, vol. 327, pp.679-682.