PARENT SESSION
Organized Oral Session 43: Complex consequences of spatial subsidies to food webs
Organizer(s): JM Kraus and WB Anderson
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 511 B, Level 5, Palais des congrès de Montréal

Hierarchical timescales in food-web dynamics: A theoretical framework for the indirect effects of allochthonous inputs.

Takimoto, Gaku^{*,1, 2}, Iwata, Tomoya³, Murakami, Masashi¹, Baxter, Colden⁴, ¹ Hokkaido University, Tomakomai, Hokkaido, Japan² Yale University, New Haven, Connecticut, USA³ University of Yamanashi, Kofu, Yamanashi, Japan⁴ Idaho State University, Pocatello, Idaho, USA

ABSTRACT- Food-web dynamics are the interactions of multiple processes occurring on various timescales. Complexity arising from such multi-scale food-web dynamics manifests itself in accumulating evidence of divergent predator-mediated indirect effects of allochthonous inputs (i.e., resources or prey originating from the outside of presumed food-web boundaries) on in situ prey (i.e., prey produced within the boundaries) from a variety of natural systems. According to hierarchy theory, multi-scale complex systems can be decomposed into simpler systems based on hierarchies in the timescales of involved processes. Applying this hierarchical conceptualization to food-web dynamics, we develop a unified theoretical framework to explain various indirect effects (i.e., positive, negative, or insignificant) that have been found empirically. The framework integrates the temporal variation of allochthonous inputs into physiological, behavioral, demographic, and evolutionary processes causing apparent competition and mutualism. We analyze different circumstances in terms of whether these processes are faster or slower than the timescale of allochthonous input variation. Our theoretical results and successful explanations of empirical examples demonstrate the significance of the hierarchical timescales of food-web dynamics in determining the indirect effects of allochthonous inputs, and more generally their advantages in understanding ecological complexity.

Key words: Hierarchy theory, Press perturbation, Subsidy, Temporal variation