A homoclinic route to chaos in omnivore communities

TL;DR

This paper demonstrates how homoclinic bifurcations in a minimal intraguild predation model lead to chaos, explaining complex population dynamics observed in ecological omnivore networks.

Contribution

It introduces a minimal model showing the emergence of homoclinic orbits and chaos in omnivore communities, linking mathematical bifurcation theory to ecological complexity.

Findings

Multiple coexistence modes identified, from regular oscillations to chaos.

Numerical simulations confirm the presence of Shilnikov homoclinic orbits.

Model reproduces patterns observed in natural omnivore networks.

Abstract

Omnivory, where species feed across multiple trophic levels, is a widespread feature of ecological networks. A key mechanism underlying such complexity is intraguild predation (IGP), in which a top predator consumes both an intermediate predator and a shared resource. Here, we show that Shilnikov homoclinic orbits emerge in a minimal intraguild predation model, triggering a cascade of homoclinic bifurcations near a saddle-focus equilibrium that culminates in chaos. Numerical simulations and Lyapunov spectrum analysis reveal multiple coexistence modes, ranging from regular oscillations to Shilnikov homoclinic orbits and chaos. Our model quantitatively reproduces patterns observed in natural omnivore networks, providing mechanistic insights into complex population fluctuations in ecological systems.