Deborah Kohn, Research Associate

Department of Ecology and Evolutionary Biology
University of Toronto
25 Willcocks Street
Toronto, Ontario, Canada
M5S 3B2
Phone: (416) 978-5603


  B. Sc.

(1986) Ecology and evolution. McGill University, Montreal.

  M. Sc. Ecological

(1988) Biogeography of very small islands: a study of flowering plants and habitats in Shetland. Imperial College Centre for Environmental Technology, University of London.

  Ph. D. Biology

(1998) Effects of genetic variability and founder number in small populations of an annual plant (Brassica nigra). Imperial College, Silwood Park, University of London, UK.

  Current Position

(2009-present) EEB Research Associate, Professor Barrett's lab, Department of Ecology and Evolutionary Biology, University of Toronto

  Research Interests

Conservation ecology, ecological significance of genetic variability, viability of small populations, adaptive and experimental management.


  Current research

  Hybridization in UK bluebells (Hyacinthoides)



The threat to the UK's native bluebell, Hyacinthoides non-scripta, posed by hybridization with non-native 'spanish' bluebells (H. hispanica and/or H. x massartiana) is probably the best-publicized conservation issue in Britain. The native bluebell has the distinction of being ubiquitous in Britain's temperate climates, and the favourite wildflower by popular vote. However the British love of bluebells has extended to the equally widespread planting of ornamental varieties derived from other species, and in the last decade the extent of their prevalence in the wild has raised considerable alarm. In spite of the issue's high profile, it is not known whether non-natives arise from in-situ hybridization between natives and introduced bluebells. In the absence of evidence, an alternative explanation - that they result from the vegetative spread of deliberate introductions, either as ornament or as waste - is equally credible. Despite this debate, the assertion that the two taxa hybridise freely recurs throughout the literature. We have found that viable seeds can be produced by hand-pollination, but the dynamics of naturally-occurring hybridization have important consequences for the future of the native species. In addition, the progress of this secondary contact between two distinct but closely-related species contributes a model for genetic invasion, increasingly recognized as a significant route of anthropogenic alteration of native biota. The current study builds on four years of work by RBGE and NHM which produced baseline data on distributions and genetic marker systems capable of distinguishing bluebell taxa.


UK's native bluebell photo

UK's native bluebell,
Hyacinthoides non-scripta

Hyacinthoides alien

Non-native 'spanish' bluebell

Hyacinthoides alien

Non-native 'spanish' bluebell

  Objectives and methods


1) Are natives producing hybrid seeds in natural populations? 2) Is production of hybrid seed by natives predictable from the availability of alien flowers? 3) Over what scale does bluebell pollen travel? 4) Is native seed set reduced by receipt of alien pollen, or by flow of native pollen to aliens?

These initial questions are being addressed by field-based experiments in which proximity, nearest neighbours identity and relative numbers of each taxon are manipulated. In 2009 we set up a small experimental array, consisting of 16 groups of 3 flowering individuals each, two natives + one alien, each group 5-6 m from others. Focal native plants thus were in 2:1 majority within the array, and each had one native and one alien as nearest neighbours. Seeds produced will be genotyped for paternity, either native or alien and either within the array or beyond it. This design will be scaled up in 2010. Also in 2010 a second experiment will be conducted in which focal natives will be set in various positions and group sizes within the reference alien population. All maternal plants will be genotyped along with their progeny.



 Previous Research & Publications

2007-2008 Post-doctoral researcher, Centre for Ecology and Hydrology, Edinburgh. ALARM project (, European Union Sixth Framework Programme. Climate and density effects on performance of native and alien bluebells. in prep (among others):

  • Kohn, D.D., Hulme, P.E., Hollingsworth, P.M. Contrasting reproductive strategies in sympatric UK native and alien bluebells.

2004-2007 Research Fellow, CEH Banchory/Royal Botanic Garden Edinburgh. Is the native British bluebell threatened by Spanish and hybrid bluebells? Natural Environment Research Council through the Daphne Jackson Trust.

  • Kohn, D., Hulme, P.E., Hollingsworth, P.M, Butler, A. 2009. Are native bluebells (Hyacinthoides non-scripta) at risk from alien congenerics? Evidence from distributions and co-occurrence in Scotland. Biological Conservation 142, 61-74.

2003 Centre for Conservation Science, University of Stirling. Seed dispersal in the invasive Rhododendron ponticum.

  • Stephenson, C.M., Kohn, D.D., Park, K.J., Atkinson, R., Edwards, C., Travis, J.M.J., 2007. Testing mechanistic models of seed dispersal for the invasive Rhododendron ponticum (L.). Perspectives in Plant Ecology, Evolution and Systematics 9 (1), 15-28.

1998-2000 Biodiversity Action Plan research on twinflower (Linnaea borealis). Scottish Natural Heritage contract to Richard Ennos & Colin Legg, IERM, University of Edinburgh.

  • Kohn, D., Lusby, P., 2004. Translocation of Twinflower (Linnaea borealis L.) in the Scottish Borders. Botanical Journal of Scotland 56(1), 25-37.
  • Kohn, D. 2004. Species dossier for twinflower, Linnaea borealis L.. Plantlife UK.
  • Kohn, D. & Ennos, R. 2000. Action Plan Research on Twinflower. Final Report to Scottish Natural Heritage, contract no. R/AC3/BAT/98/58.

1989-1992 Research assistant, PROSAMO (Planned Release of Selected and Modified Organisms), Imperial College, Silwood Park, University of London, UK. Relative performance of transgenic and conventional crop plants in natural habitats (Cornwall, Berkshire, Sutherland, UK).

  • Crawley, M.J., Brown, S.L., Hails, R.S., Kohn, D.D., Rees, M., 2001. Transgenic crops in natural habitats. Nature 409, 682-683.
  • Hails, R.S., Rees, M., Kohn, D.D. & Crawley, M.J. , 1997. Burial and seed survival in Brassica napus subsp. oleifera and Sinapis avensis including a comparison of transgenic and non-transgenic lines of the crop. Proc. R. Soc. London B 264, 1-7.
  • Crawley, M.J., Hails, R.S., Rees, M., Kohn, D. & Buxton, J. 1993. Ecology of transgenic oilseed rape in natural habitats. Nature 363, 620-623.
  • Rees, M., Kohn, D., Hails, R., Crawley, M. & Malcolm, S. 1991. An ecological perspective to risk assessment. pp 9-24 in Biological Monitoring of Genetically Engineered Plants and Microbes. International symposium on the biosafety results of field tests of genetically modified plants and microorganisms, Kiawah, South Carolina, November 1990. USDA, Washington, D.C. and Clemson University, South Carolina.

MSc. (1988) Biogeography of very small islands: a study of flowering plants and habitats in Shetland. Imperial College Centre for Environmental Technology, University of London.

  • Kohn, D.D. & Walsh, D.M., 1994. Plant species richness - the effect of island size and habitat diversity. Journal of Ecology 82, 367-377.