Eco-Evolutionary Dynamics of a Population with Randomly Switching Carrying Capacity

TL;DR

This study models how environmental fluctuations in resource availability influence the eco-evolutionary dynamics of a population with two competing strains, revealing conditions under which cooperation or freeriding strategies are favored.

Contribution

It introduces a model combining demographic and environmental noise to analyze eco-evolutionary dynamics with switching carrying capacity and public good production.

Findings

Environmental variability significantly impacts population size and composition.

Cooperation is favored under certain environmental conditions, but can be outcompeted by freeriding.

Coupled demographic and environmental noise affects size distribution and social dilemmas.

Abstract

Environmental variability greatly influences the eco-evolutionary dynamics of a population, i.e. it affects how its size and composition evolve. Here, we study a well-mixed population of finite and fluctuating size whose growth is limited by a randomly switching carrying capacity. This models the environmental fluctuations between states of resources abundance and scarcity. The population consists of two strains, one growing slightly faster than the other, competing under two scenarios: one in which competition is solely for resources, and one in which the slow ("cooperating") strain produces a public good that benefits also the fast ("freeriding") strain. We investigate how the coupling of demographic and environmental (external) noise affects the population's eco-evolutionary dynamics. By analytical and computational means, we study the correlations between the population size and its composition, and discuss the social-dilemma-like "eco-evolutionary game" characterizing the public good production. We determine in what conditions it is best to produce a public good; when cooperating is beneficial but outcompeted by freeriding, and when the public good production is detrimental for cooperators. Within a linear noise approximation to populations of varying size, we also accurately analyze the coupled effects of demographic and environmental noise on the size distribution.