Single-species models for many-species food webs

Area of Science:

• Ecology
• Population Dynamics
• Mathematical Biology

Background:

• Most species exist in species-rich food webs, yet population dynamics models traditionally focus on one or two species.
• The relevance of simplified models to real-world, complex ecosystems remains a key question in ecological research.

Purpose of the Study:

• To investigate the validity of one-species population models for generalist consumers within multi-species food webs.
• To determine if simplified models can accurately represent the dynamics of generalist species in complex ecological communities.

Main Methods:

• Analyzing two-species consumer-resource models to identify conditions under which they simplify to one-species dynamics.
• Utilizing cyclic populations as a model system due to their clearer underlying mechanisms.
• Distinguishing between one-species cycles and consumer-resource cycles based on their distinct periods.
• Analyzing extensive time-series data from natural cyclic populations.

Main Results:

• Two-species population models simplify to one-species dynamics when the resource population's recruitment is independent of its abundance.
• One-species population cycles exhibit characteristic periods that differ from consumer-resource cycles.
• Empirical analysis of numerous natural cyclic populations revealed that generalist consumers predominantly display periods consistent with one-species dynamics.

Conclusions:

• Generalist consumers in species-rich food webs often exhibit population dynamics that can be effectively represented by one-species models.
• The observed dynamics suggest that simplified, one-species models are a valid and useful tool for understanding the population dynamics of generalist consumers in complex ecosystems.