Wednesday, August 8, 2007: 1:30 PM-5:00 PM
A4&5, San Jose McEnery Convention Center
OOS 34 - Ecological consequences of size-structured interactions
The classical community ecology approach assumes that a species is a homogenous, unstructured entity and that all individuals occupy the same distinct trophic position. While this simplification often improves the tractability of food-web models, their utility may be limited because natural populations are often comprised of individuals that differ in size and developmental stage. This size-structure creates size-structured interactions in which the type and strength of interactions among members of the community is determined by the current relative size of the involved individuals. As a consequence, the size structure within a population strongly determines species population dynamics, inter-specific interactions, and the structure and dynamics of communities. The importance of population size structure has been recognized in the past, but recent studies that have specifically considered the role of size-structured interactions have improved our understanding of competition, coexistence among intraguild predators, host-parasitoid or host-disease interactions, and population dynamics of cannibalistic species. This recent empirical and theoretical work represents an innovative step forward because it attempts to reconcile erroneous predictions made by simple models that do not account for size structured interactions with complex natural systems. However, to date there have been no coherent explanations of when it is imperative to include size structure to predict community dynamics and ecosystem processes. What are the specific mechanisms that lead to the observed deviations of dynamics between size structured and unstructured systems? How common are these mechanisms in natural systems and what is their general importance compared to other community processes? This session will focus on new original research addressing these specific questions and will provide a cohesive framework to evaluate the causes and implications of size structure at the population and community-level in a wide range of ecological contexts. For this purpose, the session will incorporate both theoretical and empirical perspectives on this issue and include talks from leading researchers working in diverse systems.
Organizer:	Volker H.W. Rudolf, University of Virginia
Co-organizer:	Patrick W. Crumrine, Rowan University and Blandy Experimental Farm
Moderator:	Patrick W. Crumrine, Rowan University and Blandy Experimental Farm
1:30 PM	OOS 34-1		Ecosystem stoichiometry drives stoichiometry coevolution in size-structured food webs James C. Stegen, University of Arizona, Regis Ferriere, University of Arizona, Brian J. Enquist, University of Arizona
1:50 PM	OOS 34-2		Impacts of alternative prey and intraguild predators on size-structured interactions in larval odonates Patrick W. Crumrine, Rowan University
2:10 PM	OOS 34-3		Culling prey promotes predator reinvasion: A whole lake experiment Lennart Persson, Umea University, Per-Arne Amundsen, University of Tromsø, André M. De Roos, University of Amsterdam, Anders Klemetsen, University of Tromsø, Rune Knudsen, University of Tromsø, Raul Primicerio, University of Tromsø
2:30 PM	OOS 34-4		Crossing the boundary: Coupling dynamics of ecosystems through complex life cycles Sebastian J. Schreiber, College of William & Mary, Volker H.W. Rudolf, University of Virginia
2:50 PM	OOS 34-5		Causes and consequences of population cycles in a highly size- and stage-structured population Scott Wissinger, Allegheny College, Howard Whiteman, Murray State University
3:10 PM			Break
3:20 PM	OOS 34-6		Community consequences of overcompensation in stage-specific biomass due to size-selective mortality: Emergent Allee effects and emergent facilitation André M. De Roos, University of Amsterdam, Tim Schellekens, Umeå University, Tobias Van Kooten, Umeå University, Karen Van de Wolfshaar, University of Amsterdam, David Claessen, University of Amsterdam, Lennart Persson, Umeå University
3:40 PM	OOS 34-7		Host stage-structure allows for persistence of an amphibian pathogen Cherie Briggs, University of California Berkeley
4:00 PM	OOS 34-8		Cannibalism in the prey: Emergent indirect interactions, mortality risk reduction, and consequences for predator-prey dynamics Volker H.W. Rudolf, University of Virginia
4:20 PM	OOS 34-9		Interstage competition and population cycles in size-structured populations Roger N. Nisbet, University of California, Santa Barbara, William Nelson, University of Alberta, Edward McCauley, University of Calgary
4:40 PM	OOS 34-10		Food webs: Scaling from the individuals to ecosystems Guy Woodward, Queen Mary University of London, Philip H. Warren, University of Sheffield

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