Coherent Structures and Travelling Waves in Spatial Replicators from a Biased Volterra Lattice

TL;DR

This paper investigates the spatial dynamics of a biased Volterra lattice, revealing traveling waves in certain cycle sizes and stationary 'frozen waves' in others, with implications for ecological niche formation.

Contribution

It introduces a bias into the Volterra lattice, extending the classic rock-paper-scissors model, and characterizes the resulting traveling and stationary wave solutions.

Findings

Traveling waves found in 5- and 6-cycle dynamics.

Frozen wave solutions occur in 4-, 6-, and 8-cycle dynamics.

Stationary solutions may represent ecological niches.

Abstract

The Volterra lattice is a well-known integrable family that is also a special class of replicator dynamics and whose members can be put in one-to-one correspondence with the directed cycle graphs. In this paper, we study a variation of the Volterra lattice by introducing a bias term in the replicator interaction matrix. The resulting system can still be put into one-to-one correspondence with the directed cycles, and the dynamics offer one generalisation of the classic rock-paper-scissors evolutionary game. We study the resulting spatial dynamics of this family, showing that travelling wave solutions are present in those dynamics corresponding to the directed 5- and 6-cycles, but not the 4-cycle. Instead, the 4-cycle exhibits a set of stationary solutions that we call `frozen waves' that are similar to but distinct from Turing patterns. This type of solution is also found in the dynamics generated from the directed 6- and 8-cycles. We discuss how these stationary solutions can represent naturally emergent ecological niches in these systems, and offer generalizing conjectures for the existence of both travelling wave solutions and frozen wave solutions in this family of dynamics as a potential program of future investigation.