Effects of population growth on the success of invading mutants

TL;DR

This paper investigates how population growth influences the likelihood of mutants reaching fixation, revealing non-monotonic effects and breakdown of classical laws in evolutionary dynamics through simulations and mathematical modeling.

Contribution

It introduces a decoupled model of competition and growth, demonstrating complex growth effects on mutant fixation and providing a stochastic differential equation approximation.

Findings

Non-monotonic fixation probability with growth rate

Growth can increase mutant success under certain conditions

Breakdown of the 'one-third law' in growth scenarios

Abstract

Understanding if and how mutants reach fixation in populations is an important question in evolutionary biology. We study the impact of population growth has on the success of mutants. To systematically understand the effects of growth we decouple competition from reproduction; competition follows a birth--death process and is governed by an evolutionary game, while growth is determined by an externally controlled branching rate. In stochastic simulations we find non-monotonic behaviour of the fixation probability of mutants as the speed of growth is varied; the right amount of growth can lead to a higher success rate. These results are observed in both coordination and coexistence game scenarios, and we find that the 'one-third law' for coordination games can break down in the presence of growth. We also propose a simplified description in terms of stochastic differential equations to approximate the individual-based model.