A numerical approach to determine mutant invasion fitness and evolutionary singular strategies

TL;DR

This paper introduces a numerical method combining stochastic and deterministic models to analyze mutant invasion fitness and identify evolutionary singular strategies in structured population models, exemplified by a chemostat model.

Contribution

It presents a novel numerical approach linking stochastic and deterministic invasion fitnesses to determine evolutionary strategies in structured models.

Findings

The method accurately predicts invasion success in chemostat models.

It generalizes to a broad class of evolutionary models with stochastic-deterministic links.

The approach facilitates the analysis of evolutionary stability and convergence.

Abstract

We propose a numerical approach to study the invasion fitness of a mutant and to determine evolutionary singular strategies in evolutionary structured models in which the competitive exclusion principle holds. Our approach is based on a dual representation, which consists of the modelling of the small size mutant population by a stochastic model and the computation of its corresponding deterministic model. The use of the deterministic model greatly facilitates the numerical determination of the feasibility of invasion as well as the convergence-stability of the evolutionary singular strategy. Our approach combines standard adaptive dynamics with the link between the mutant survival criterion in the stochastic model and the sign of the eigenvalue in the corresponding deterministic model. We present our method in the context of a mass-structured individual-based chemostat model. We exploit a previously derived mathematical relationship between stochastic and deterministic representations of the mutant population in the chemostat model to derive a general numerical method for analyzing the invasion fitness in the stochastic models. Our method can be applied to the broad class of evolutionary models for which a link between the stochastic and deterministic invasion fitnesses can be established.