NCEAS Project 2287

Spatial ecology: The role of space in population dynamics and interspecific interactions

  • David Tilman
  • Peter Kareiva

ActivityDatesFurther Information
Workshop21st—24th January 1996Participant List  

Abstract
All living organisms are spatially discrete. Each individual occupies a particular locality at a particular point in time. All interact most strongly with those individuals that are close by. It is our overall goal to assemble a group of researchers to explore the effects of this fundamental aspect of organism and environment. There have been many major recent advances in our understanding of how spatially explicit processes influence the dynamics of individual species and the structure, dynamics and diversity of ecological communities. These advances have exposed the limitations of traditional non-spatial approaches, and uncovered a rich array of unexpected phenomenon that seemingly occur only when space is considered explicitly. For instance, we now know that neighborhood interactions and local dispersal can lead to clustering even in physically homogeneous habitats (e.g., Durrett and Levin 1994). We also know that a combination of nonlinear local dynamics and larger-scale dispersal can produce in predator-prey systems a remarkable variety of spatial patterns, such as spiral waves of predator and prey sweeping through a habitat, spatial chaos, or even a crystal-like lattice of predator and prey (Hassell, Commins and May 1994). From a different theoretical perspective, we have learned that dispersal (in a sufficiently large spatial arena) can stabilize predator-prey and host-parasite interactions that are unstable in small or homogeneous habitats (Hassell and May 1995). Likewise, a new solution to the Prisoner's Dilemma was discovered when it was solved in an explicitly spatial setting (Nowak and May 1995). Interestingly, theory also suggests that many of these spatial effects may be captured with "pseudo-spatial", models in which location or distance are not explicitly represented, but instead space is thought of in terms of equally accessible patches that are either occupied or vacant (e.g., metapopulation models of Levins 1969, Horn and MacArthur 1972, Hastings 1980, Gilpin and Hanski 1991, Tilman 1994). While these "patch occupancy models" are appealing for their simplicity it is not generally known when they are appropriate simplifications.

Thus, one fundamental question regarding spatial ecology concerns how modelers should go about representing space. Is it necessary to consider the explicit spatial location of all individuals? Or, are cellular automata reasonable approximations? Or, might metapopulation-like pseudospatial models suffice? Are there added insights, and what are these insights, that come from increasingly realistic considerations of space? Simple models, such as metapopulation models, are often analytically tractable because of their assumption of global dispersal. In contrast, the more realistic reaction-diffusion and other partial differential equation models are tractable only for cases that are often too simple to be of great ecological interest. Cellular automata models, and more spatially complex explicit computer simulations, have much greater ecological reality, but suffer from the difficulty of generalization. Such issues need to be addressed via comparison and synthesis of these different approaches to space -- a task best completed by gathering together researchers with expertise in these different areas for extended discussion, analysis and collaboration.

In addition to theoretical questions regarding models of ecological dynamics in space, there is an equally challenging set of questions faced by field-researchers and experimentalists. Theory is of greatest use when it informs how we view nature, and especially when there is an interaction between theory, field observations, and experimental tests of alternative hypotheses. Thus, another area in need of major advances is the formulation of practical testable predictions, and the need for field observations and experiments that can guide the development of new theories. Thus, we seek not just a gathering of modelers, but formation of a group of theoreticians and of experimentalists who are capable of forcing pragmatic guidelines and suggestions out of the theoreticians. Among our immediate goals is an improved understanding of the spatial patterns that result from interactions in spatial habitats. To date, there have been few attempts to study the spatial patterns of organisms in nature, and the dynamics of these spatial patterns. The ability to better visualize both actual and theoretically predicted spatial patterns and spatial dynamics could prove important in integrating theory and nature.

To accomplish our goals, we propose the establishment of a working group on "Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions." The first task facing this working group would be the synthesis and distillation of current knowledge into a tightly edited cohesive book that would be designed to lay out the major insights provided by spatial approaches, the multitude of unanswered questions, and the approaches that could be taken in field observational and experimental studies, as well as in additional theory, to address these issues. We seek a book that will inspire much additional research in this area, a book more in the spirit of a "Princeton Monograph" than either a textbook or a symposium volume. In addition, we would like this working group to continue to pursue this synthesis of theory, observation, and experimentation even after a book has been produced. We envision the composition of the working group to be somewhat fluid, and have planned no further than our first two meetings.

TypeProducts of NCEAS Research
Book Chapter Antonovics, Janis; Thrall, Peter H.; Jarosz, Andrew M. 1997. Genetics and the spatial ecology of species interactions. Edited by Tilman, David; Kareiva, Peter. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 158-180.
Book Chapter Ferguson, Neil; May, Robert M.; Anderson, Roy M. 1997. Measles: Persistence and synchronicity in disease dynamics. Edited by Tilman, David; Kareiva, Peter. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 137-157.
Book Chapter Hanski, Ilkka. 1997. Predictive and practical metapopulation models: The incidence function approach. Edited by Tilman, D.; Kareiva, P.. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 21-45.
Book Chapter Hassell, Michael; Wilson, Howard. 1997. The dynamics of spatially distributed host-parasitoid systems. Edited by Tilman, David; Kareiva, Peter. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 75-110.
Book Chapter Homes, Elizabeth E. 1997. Basic epidemiological concepts in a spatial context . Edited by Tilman, David; Kareiva, Peter. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 111-136.
Book Chapter Lehman, Clarence L.; Tilman, David. 1997. Competition in spatial habitats. Edited by Tilman, David; Kareiva, Peter. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 185-203.
Book Chapter Levin, Simon A.; Pacala, Stephen W. 1997. Theories of simplification and scaling of spatially distributed processes. Edited by Tilman, D.; Kareiva, P.. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 271-295.
Book Chapter Lewis, Mark A. 1997. Variability, patchiness and jump dispersal in the spread of an invading population. Edited by Tilman, D.; Kareiva, P.. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 46-69.
Book Chapter Pacala, Stephen W.; Levin, Simon A. 1997. Biologically generated spatial pattern and the coexistence of competing species. Edited by Tilman, David; Kareiva, Peter. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 204-232.
Book Chapter Roughgarden, Joan. 1997. Production functions from ecological populations: A survey with emphasis on spatially implicit models. Edited by Tilman, David; Kareiva, Peter. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 296-317.
Book Chapter Steinberg, Ellie; Kareiva, Peter. 1997. Challenges and opportunities for empirical evaluation of spatial theory. Edited by Tilman, David; Kareiva, Peter. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 318-332.
Book Chapter Tilman, David; Lehman, Clarence L. 1997. Habitat destruction and species extinctions. Edited by Tilman, David; Kareiva, Peter. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press . Princeton. Pages 233-249.
Book Chapter Tilman, David; Lehman, Clarence L.; Kareiva, Peter. 1997. Population dynamics in spatial habitats. Edited by Tilman, David; Kareiva, Peter. Spatial Ecology: The Role of Space in Population Dynamics and Interspecific Interactions. Princeton University Press. Princeton. Pages 3-20.
Book Tilman, David; Kareiva, Peter. 1997. Spatial ecology: The role of space in population dynamics and interspecific interactions. Princeton University Press. Princeton.