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Alexander Flecker


photo of Alexander Flecker

Dale R Corson Bio Science Wing, Room E211

Educational Background

Ph.D., Zoology, University of Maryland (1990)

M.S., Zoology, University of Maryland (1984)

B.S, Zoology, Oregon State University (1980)



I am a Professor in the Department of Ecology and Evolutionary Biology. I am also a member of the graduate fields of Ecology and Evolutionary Biology, International Development, Natural Resources, and Conservation and Sustainable Development, and an Associate Member of the Latin American Studies Program. After receiving my Ph.D. in Zoology (Ecology and Evolution concentration) in 1990, I was a Postdoctoral Fellow at the University of Otago in New Zealand (1991-1993), and joined the Cornell faculty in 1995. My lab has worked extensively in the Neotropics, including research sites in Venezuela , Bolivia, Ecuador, Mexico, Peru, Trinidad, and the Dominican Republic.

In addition to teaching courses such as BioEE 1610 Ecology and the Environment; BioEE 4560/NTRES 4560 Stream Ecology and BioEE 990 Independent Undergraduate Research in Biology at Cornell, I have served as an invited course instructor in Costa Rica for the Organization for Tropical Studies and at the University of Coimbra in Portugal.



Food webs, tropical stream ecosystems, ecosystem engineers, ecological stoichiometry, ecosystem subsidies, eco-evolutionary interactions, fishes, biogeochemistry, biodiversity and ecosystem function


  • Ecology and Evolutionary Biology

Graduate Fields

  • Ecology and Evolutionary Biology
  • Natural Resources


Research in my lab is at the interface between community and ecosystem ecology and aims to understand the functional significance of biodiversity. Much of the research focuses on stream ecosystems in both the tropics and temperate zone, addressing questions pertaining to the importance of species diversity and identity for ecosystem functioning. My research team has found that species that engineer their physical and chemical environments can be particularly important drivers of ecosystem structure and function. For example, in river systems of South America, migratory fishes can be significant material subsidies as nutrient vectors, or can act as important modulators of ecosystem processes such as carbon and nitrogen cycling or as seed dispersal agents in vast flooded forests. In addition, my lab is interested in interactions between evolutionary and ecosystem processes in natural systems, working on the influence of phenotypic variation in Trinidadian guppies on stream ecosystem functioning. A further research theme is to use trait-based approaches for understanding the relative vulnerability of species to climate change in tropical versus temperate riverine systems. Our research team is especially interested in placing their work in the context of ecosystem-level consequences of biodiversity loss due to factors such as overharvest and habitat destruction, or species additions via invasions. Part of the research has an international focus, especially in freshwater ecosystems of South America, Mesoamerica, and the Caribbean. The research integrates a variety of approaches for testing ideas including observations of natural ecosystems over space and time, lab and mesocosm experiments, and whole-ecosystem manipulations. Major research topics include: (1) Role of animals in influencing community and ecosystem processes in aquatic systems. Research projects include work in Neotropical streams (Venezuela, Trinidad, Mexico, Ecuador, Peru), high Andean hypersaline lagoons (Bolivia), desert streams (New Mexico), and north temperate streams (Colorado, New York); (2) Importance of migratory fish as ecosystem subsidies, and the influence of overharvest on migratory species; (3) Community and ecosystem consequences of biological invasions and species loss; (4) Interactions between evolutionary and ecosystem processes.




  • Kwon, S. Y., P. M. McIntyre, A. S. Flecker, and L. Campbell. 2012. Mercury biomagnification in the food web of a neotropical stream. Science of the Total Environment 417-418:92-97, doi:10.1016/j.scitotenv.2011.11.060.
  • Hall, Jr., R. O., B. W. Taylor, and A. S. Flecker. 2011. Detritivorous fish indirectly reduce insect secondary production in a tropical reiver. Ecosphere 2(12):135, doi:10.1890/ES11-00042.1.
  • Anderson, J.T., T. Nuttle, J.S. Saldaña Rojas, T.H. Pendergast, and A.S. Flecker. 2011. Extremely long-distance seed dispersal by an overfished Amazonian frugivore. Proceedings of the Royal Society B. 278:3329-3335, doi: 10.1098/rspb.2011.0155. 
  • Boyero, L., and others. 2011. A global experiment suggests climate warming will not accelerate litter decomposition in streams but might reduce carbon sequestration. Ecology Letters 14: 289–294.
  • Capps, K.A., M.T. Booth, S.M. Collins, M.A. Davison, J.M. Moslemi, J.L. Simonis, R.W. El-Sabaawi, and A.S. Flecker.  2011. Nutrient diffusing substrata: a field comparison of commonly used methods to assess nutrient limitation. Journal of the North American Benthological Society. 30: 522-532.
  • Flecker, A.S., P.B. McIntyre, J.W. Moore, J.T. Anderson, B.W. Taylor, and R.O. Hall. 2010. Migratory fishes as material and process subsidies in riverine ecosystems. American Fisheries Society Symposium 73:559-592.
  • Bassar, R.D., M.C. Marshall, A. López-Sepulcre, E. Zandonà, S.K. Auer, J. Travis, C.M. Pringle, A.S. Flecker, S.A. Thomas, D.F. Fraser, and D.N. Reznick. 2010. Local adaptation in Trinidadian guppies alter ecosystem processes. Proceedings of the National Academy of Sciences 107: 3616-3621.
  • McIntyre, P.B. and A.S. Flecker. 2010. Ecological stoichiometry as in integrative framework in stream fish ecology. American Fisheries Society Symposium 73:539-558.
  • Winemiller, K.O., A.S. Flecker, and D.J. Hoeinghaus. 2010. Patch dynamics and environmental heterogeneity in lotic ecosystems. Journal of the North American Benthological Society 29:84–99.
  • Corman, J.R., P.B. McIntyre, B. Kuboja, W. Mbemba, D. Fink, C.W. Wheeler, C. Gans, E. Michel, and A.S. Flecker. 2010. Upwelling couples chemical and biological dynamics in the pelagic and littoral zones of Lake Tanganyika, East Africa. Limnology and Oceanography 55:214–224.
  • Anderson, J.T., J. Saldaña Rojas, and A.S. Flecker. 2009. High quality seed dispersal by fruit-eating fishes in Amazonian floodplain habitats. Oecologia 161:279–290.
  • Flecker, A.S. 2009. Crossing borders: promoting graduate research in the developing world: Faculty Response.  Frontiers in Ecology and the Environment 7: 334.
  • Knoll, L.B., P.B.McIntyre, M.J. Vanni, and A.S. Flecker. 2009. Feedbacks of consumer nutrient recycling on producer biomass and stoichiometry: separating direct and indirect effects. Oikos 118:1732-1742.
  • McIntyre, P.B., A.S. Flecker, M.J. Vanni, J.M. Hood, B.W. Taylor, and S.A. Thomas. 2008. Fish distributions and nutrient recycling in a Neotropical stream: can fish create biogeochemical hotspots? Ecology 89: 2335–2346.
  • Power, A.G. and A.S. Flecker. 2008. The role of vector diversity in disease dynamics.  Pp.30-47 In: Ostfeld, R. S., F. Keesing, and V. Eviner (eds.). Infectious Disease Ecology: Effects of Disease on Ecosystems and of Ecosystems on Disease.  Princeton University Press, Princeton, NJ.
  • McIntyre, P.B., L.E. Jones, A.S. Flecker, and M.J. Vanni. 2007. Fish extinctions alter nutrient recycling in tropical freshwaters. Proceedings of the National Academy of Sciences 104: 4461-4466.