Research Interests

My research seeks explanations for the remarkable diversity of floral design and display that characterizes angiosperms. I expect that much of this diversity represents differences in reproductive function, so that my specific research projects address the roles of design and display in particular pollination and mating environments. Clearly this objective is too large to be applied individually to all 250,000 angiosperm species, so I adopt a conceptual approach, often supplemented by formal mathematical theory, which is guided by my empirical experience with pollinator behaviour and reproduction by diverse species. At the moment, some of my projects include: characterizing how general interactions between pollinators and flowers determine the pattern of pollen dispersal by individual pollinators; clarifying the function of stigma and anther positions in flowers; developing a general conception of the tradeoff between self- and cross-pollination (pollen discounting) and exposing its implications for floral and mating-system evolution; explaining the common overproduction of ovules within ovaries; and identifying the function(s) of pollen size.

Courses Taught

Graduate Students

Selected publications

• Garibaldi, L.A., M.A. Aizen, A.M. Klein, S.A. Cunningham and L.D. Harder. 2011. Global growth and stability in agricultural yield decrease with pollinator dependence. Proceedings of the National Academy of Sciences, U.S.A. 108:5909–5914. (pdf file)
• Hargreaves A. L., L. D. Harder and S. D. Johnson. 2010. Native pollen thieves reduce the reproductive success of a hermaphroditic plant, Aloe maculata. Ecology 91:1693-1703. (pdf file)
• Harder, L. D. and M. A. Aizen.2010.Floral adaptation and diversification under pollen limitation.Philosophical Transactions of the Royal Society, B 365:529-543. (pdf file)
• Harder, L. D. and S. D. Johnson. 2009. Darwin’s beautiful contrivances: evolutionary and functional evidence for floral adaptation. New Phytologist 183:530-545.(pdf file)
• Aizen, M. A. and L. D. Harder. 2009. The global stock of domesticated honey bees is increasing at a lower rate than agricultural pollination demands. Current Biology 19:915–918.(pdf file)
  
• Hargreaves, A. L., L. D. Harder and S. D. Johnson. 2009. Consumptive emasculation: the ecological and evolutionary consequences of pollen theft. Biological Reviews 84:259-276.(pdf file)
  
• Harder, L. D., and S. D. Johnson. 2008. Function and evolution of aggregated pollen in angiosperms. International Journal of Plant Sciences 169:59-78.(pdf file)
  
• Harder, L. D., S. A. Richards and M. B. Routley. 2008. Effects of reproductive compensation, gamete discounting and reproductive assurance on mating-system diversity in hermaphrodites. Evolution 62:157-172.(pdf file)
• Aizen, M. A., and L. D. Harder. 2007. Expanding the limits of the pollen-limitation concept: effects of pollen quantity and quality. Ecology 88:271-281. (pdf file)
• Prusinkiewicz, P., Y. Erasmus, B. Lane, L. D. Harder and E Coen. 2007. Evolution and development of inflorescence architectures. Science 316:1452-1456. (pdf file)
• Harder, L.D. and M.B. Routley. 2006. Pollen and ovule fates and reproductive performance by flowering plants. In L.D. Harder and S.C.H. Barrett (editors), Ecology and Evolution of Flowers. pp. 61-80. Oxford University Press. (pdf file)
• Jordan, C.Y., and L.D. Harder. 2006. Manipulation of bee behavior by inflorescence architecture and its consequences for plant mating. American Naturalist 167:496-509. (pdf file - 504 kb)
• Harder, L.D., and S.D. Johnson. 2005. Adaptive plasticity of floral display size in animal-pollinated plants. Proceedings of the Royal Society, Series B 272:2651-2657. [doi: rspb.2005.3268] (pdf file - 176 kb)
• Johnson, S.D., P.R. Neal, and L.D. Harder. 2005. Pollen fates and the limits on male reproductive success in an orchid population. Biological Journal of the Linnean Society 86:175-190. (pdf file - 520 kb)
• Barrett, S.C.H., and L.D. Harder. 2005. The evolution of polymorphic sexual systems in Daffodils (Narcissus). New Phytologist 165:45-53. (pdf file - 372 kb)
• Friedman, J., and L. D. Harder. 2004. Inflorescence architecture and wind pollination in six grass species. Functional Ecology 18:851-860. (pdf file - 268 kb)
• Harder, L. D., C. Y. Jordan, W. E. Gross and M. B. Routley. 2004. Beyond floricentrism: the pollination function of inflorescences. Plant Species Biology 19:137-148.(pdf file - 224 kb)
• Barrett, S. C. H., L. D. Harder, and W. W. Cole. 2004. Correlated evolution of floral morphology and mating-type frequencies in a sexually polymorphic plant. Evolution 58:964-975. (pdf file - 608 kb)
• Harder, L. D., and M. A. Aizen. 2004. The functional significance of synchronous protandry in Alstroemeria aurea. Functional Ecology 18:467-474. (pdf file - 212 kb)

Harder, L.D. and S.C.H. Barrett (editors). 2006. Ecology and Evolution of Flowers. Oxford University Press. http://www.eeb.utoronto.ca/eef/index.htm