When does cyclic dominance lead to stable spiral waves?

TL;DR

This study investigates the conditions under which cyclic dominance in a three-species ecosystem leads to stable spiral wave patterns, highlighting the role of nonlinear mobility and bifurcation dynamics.

Contribution

It provides a detailed analysis of the phase diagram for spiral wave stability using a complex Ginzburg-Landau equation derived from a three-species model.

Findings

Spiral waves are stable only in one of four identified phases.

Nonlinearity can cause spiral annihilation and uniform species dominance.

Nonlinear diffusion influences pattern dynamics away from the Hopf bifurcation.

Abstract

Species diversity in ecosystems is often accompanied by the self-organisation of the population into fascinating spatio-temporal patterns. Here, we consider a two-dimensional three-species population model and study the spiralling patterns arising from the combined effects of generic cyclic dominance, mutation, pair-exchange and hopping of the individuals. The dynamics is characterised by nonlinear mobility and a Hopf bifurcation around which the system's phase diagram is inferred from the underlying complex Ginzburg-Landau equation derived using a perturbative multiscale expansion. While the dynamics is generally characterised by spiralling patterns, we show that spiral waves are stable in only one of the four phases. Furthermore, we characterise a phase where nonlinearity leads to the annihilation of spirals and to the spatially uniform dominance of each species in turn. Away from the Hopf bifurcation, when the coexistence fixed point is unstable, the spiralling patterns are also affected by nonlinear diffusion.