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        Charlotte  Lee  
            Scholar in Residence 
            Biology Department
            Duke University
            Durham NC 27708

            070 Biological Sciences Building
            c.t.lee at duke.edu or
            charlotte.t.lee at duke.edu

               919-613-0995


 
nonlinear dynamics of interacting structured populations

I use mathematical and computer modeling to study the nonlinear dynamics of structured populations. Most biological populations exhibit age, stage, size, or other structure, and most ecological interactions (between individuals, between species, or with the environment) ultimately involve nonlinearity, so very many interesting ecological problems include both. My major research directions are 1) studying feedbacks between consumers and their resources and 2) understanding the interplay between preindustrial human populations and their environments.  Specific projects are listed below. 

►driver-dependent demography

Many consumers ingest only portions of resource individuals, or consume products or substances produced by resource individuals. Such partial consumption frequently affects resource survival, growth, and reproductive rates; these effects can be more important than consumer reductions of resource abundance.  Examples include pathogens, parasites, and some parasitoids that do not immediately nor completely consume their hosts; most herbivores, which allow their plant hosts to survive, grow, and reproduce at reduced rates; nonlethal predators; and mutualists, which may collect nectar, food bodies, or pollen from plants while pollinating or protecting them. In addition, even lethal predators frequently affect the behavior and foraging activity of surviving prey. When consumer species differ in their effects on resource demography, the resulting system dynamics can be surprising, including competitive coexistence or exclusion in otherwise unexpected situations.  

Most recently, I've developed stochastic demographic measures that can help predict how focal populations would respond to future changes in the strength of species interactions, or to changes in factors--such as climate--which can similarly affect multiple vital rates in concert.

 
► demographic dynamics of mutualism
One implication of the dynamics described above is that distinct host demographic responses to different consumer species can enable mutualists to persist in the presence of apparently competitively superior exploiters.  The resulting multi-species assemblage can have fundamentally different dynamics than does a mutualist-host species pair.  This urges a synthetic perspective of mutualism that encompasses demography as well as multiple species.   
► nutrient competition in mycorrhizal fungi
Plants frequently need mycorrhizal fungi to obtain soil nutrients; mycorrhizal fungi need carbon from plants.  This nutrient trade has frequently been studied by modeling fungal competition for access to plants and their carbon, but does not inherently alter the identity of a system's limiting nutrient.  Models show that competition for interconverting types of nitrogen could be an important factor structuring fungal communities and suggest measurements that could help determine its importance in the field. 


► food-dependent dynamics of human populations

To solve contemporary problems such as ensuring food security for a particular region or for the globe, we need more basic research on the interactions between natural resource dynamics, human population growth, and social factors such as technology, culture, politics, and economics.  I couple ecological, demographic, and social models to examine the interactions between environment, food supply, human demography, and human decision-making.  I have focused on preindustrial agricultural societies, whose dynamics are closely tied to their local environment, but am extending these approaches to hunter-gatherer societies and ultimately to modern industrial societies.  
 
    Lee, CT, and S Tuljapurkar. 2011. Quantitative, dynamic models to integrate environment, population, and society. In         Kirch, PV, ed. Roots of Conflict: Soils, Agriculture, and Sociopolitical Complexity in Ancient Hawai'i.  School of                 Advanced Research Press, Santa Fe, New Mexico. – first paragraph 

    Lee, CT, CO Puleston, and S Tuljapurkar. 2009.  Population and prehistory III: Food-dependent demography in variable     environments. Theoretical Population Biology 76: 179-188. – abstract  – Link to article at TPB 

     Lee, CT, and S Tuljapurkar.  2008.  Population and prehistory I: Food-dependent population growth in constant         environments.  Theoretical Population Biology 73: 473- 482. – abstract  – Link to article at TPB
       
    Ladefoged, TN, CT Lee, and MW Graves. 2008.  Modeling life expectancy and surplus production of dynamic                 pre-contact territories in leeward Kohala, Hawai'i. Journal of Anthropological Archaeology 27(1): 93-110.  – abstract  –  Link to article at JAA  

    Tuljapurkar, S, CT Lee, and M Figgs. 2007. Demography and food in early Polynesia. Pages 35-51 in Kirch, PV, and         J.-L. Rallu, eds. The Growth and Collapse of Island Societies: Archaeological and Demographic Perspectives from the         Pacific. Honolulu: University of Hawai’i Press. – first paragraph 

    Lee, CT, S Tuljapurkar, and P Vitousek. 2006. Risky business: spatial and temporal variation in preindustrial dryland     agriculture.  Human Ecology 34 (6): 739-763. – abstract – Link to article at Human Ecology                                     
selected publications

Lee, CT.  2017.  Elasticity of population growth with respect to the intensity of biotic or abiotic driving factors. Ecology 98: 1016–1025   --  pdf   

Lee, CT. 2015.  Inherent demographic stability in mutualist-resource-exploiter interactions.   The American Naturalist 185: 551–561  --  pdf

Lee, CT, TEX Miller, and BD Inouye. 2011.  Consumer effects on the vital rates of their resource can determine the outcome of competition between consumers.  In press at The American Naturalist.  --  abstract -- Link to article at AmNat

Lee, CT, and S Tuljapurkar. 2011. Quantitative, dynamic models to integrate environment, population, and society. Pages 111-133 in Kirch, PV, ed. Roots of Conflict: Soils, Agriculture, and Sociopolitical Complexity in Ancient Hawai'i.  School of Advanced Research Press, Santa Fe, New Mexico. – first paragraph 

Lee, CT, and BD Inouye. 2010.  Mutualism between consumers and their shared resource can promote competitive coexistence.  The American Naturalist 175: 277–288  – abstract  --  Link to article at AmNat

Lee, CT, CO Puleston, and S Tuljapurkar. 2009.  Population and prehistory III: Food-dependent demography in variable environments. Theoretical Population Biology 76: 179-188. – abstract  – Link to article at TPB 

Lee, CT, and S Tuljapurkar.  2008.  Population and prehistory I: Food-dependent population growth in constant environments.  Theoretical Population Biology 73: 473- 482. – abstract  – Link to article at TPB 

Donahue, MJ, and CT Lee. 2008. Colonization.  pp. 672-278 in SE Jorgensen and BD Fath (Editor-in-Chief), General Ecology. Vol. 1 of Encyclopedia of Ecology, 5 vols. Oxford: Elsevier. – abstract   – Link to article at ScienceDirect 

Ladefoged, TN, CT Lee, and MW Graves. 2008.  Modeling life expectancy and surplus production of dynamic pre-contact territories in leeward Kohala, Hawai'i. Journal of Anthropological Archaeology 27(1): 93-110.  – abstract  –  Link to article at JAA

Morris, WF, CA Pfister, S Tuljapurkar, CV Haridas, CL Boggs, MS Boyce, EM Bruna, DR Church, T Coulson, DF Doak, S Forsyth, J-M Gaillard, CC Horvitz, S Kalisz, BE Kendall, TM Knight, CT Lee, and ES Menges. 2008. Longevity can buffer plant and animal populations against changing climatic variability. Ecology 89 (1): 19-25. – abstract  –  Link to article at Ecology

Tuljapurkar, S, CT Lee, and M Figgs. 2007. Demography and food in early Polynesia. Pages 35-51 in Kirch, PV, and J.-L. Rallu, eds. The Growth and Collapse of Island Societies: Archaeological and Demographic Perspectives from the Pacific. Honolulu: University of Hawai’i Press. – first paragraph 

Lee, CT, S Tuljapurkar, and P Vitousek. 2006. Risky business: spatial and temporal variation in preindustrial dryland agriculture.  Human Ecology 34 (6): 739-763. – abstract – Link to article at Human Ecology

Boyce, MS, CV Haridas, CT Lee, and the NCEAS Stochastic Demography Working Group. 2006. Demography in an increasingly variable world. Trends in Ecology and Evolution 21: 141-148. – abstract –   Link to article at TREE

Lee, CT, and A Hastings.  2006.  Non-equilibrium genetic structure is robust to the shape of the dispersal distribution.  Evolutionary Ecology Research 8: 279-293. – abstract –   Link to article at EER

Chesson, P, and CT Lee.  2005.  Families of discrete kernels for modeling dispersal. Theoretical Population Biology 67 (4): 241-256.  – abstract – Link to article at TPB

Lee, CT, MF Hoopes, J Diehl, W Gilliland, G Huxel, EV Leaver, K McCann, J Umbanhowar, and A Mogilner.  2001.  Non-local concepts and models in biology.  Journal of Theoretical Biology 210: 201-219. – abstract –   Link to article at JTB

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