General non-linear imitation leads to limit cycles in eco-evolutionary dynamics

TL;DR

This paper demonstrates that using a general non-linear imitation function in eco-evolutionary models can produce limit cycles, explaining fluctuating behaviors observed in biological and social systems, unlike traditional linear models.

Contribution

It introduces the impact of non-linear imitation functions on eco-evolutionary dynamics, revealing the emergence of limit cycles and their role in coexistence and fluctuations.

Findings

Non-linear imitation leads to limit cycles in eco-evolutionary dynamics.

Internal equilibrium remains unchanged under non-linear imitation.

Limit cycles explain persistent fluctuations in cooperation and environment.

Abstract

Eco-evolutionary dynamics is crucial to understand how individuals' behaviors and the surrounding environment interplay with each other. Typically, it is assumed that individuals update their behaviors via linear imitation function, i.e., the replicator dynamics. It has been proved that there cannot be limit circles in such eco-evolutionary dynamics. It suggests that eco-evolutionary dynamics alone is not sufficient to explain the widely observed fluctuating behavior in both the biological and social systems. We extrapolate from the linear imitation function to general imitation function, which can be non-linear. It is shown that the general imitation does not change the internal equilibrium and its local stability. It however leads to limit cycles, which are never present in classical eco-evolutionary dynamics. Moreover, the average cooperation level and average environment state agree with the first and the second component of the internal fixed point. Furthermore, we estimate the location of the emergent limit cycle. On the one hand, our results provide an alternative mechanism to make cooperators and defectors coexist in a periodic way in the "tragedy of the commons" and indicates the global eco-evolutionary dynamics is sensitive to the imitation function. Our work indicates that the way of imitation, i.e., the imitation function, is crucial in eco-evolutionary dynamics, which is not true for evolutionary dynamics with a static environment.