Abstract

The environment in which a population evolves can have a crucial impact on selection. We study evolutionary dynamics in finite populations of fixed size in a changing environment. The population dynamics are driven by birth and death events. The rates of these events may vary in time depending on the state of the environment, which follows an independent Markov process. We develop a general theory for the fixation probability of a mutant in a population of wild-types, and for mean unconditional and conditional fixation times. We apply our theory to evolutionary games for which the payoff structure varies in time. The mutant can exploit the environmental noise; a dynamic environment that switches between two states can lead to a probability of fixation that is higher than in any of the individual environmental states. We provide an intuitive interpretation of this surprising effect. We also investigate stationary distributions when mutations are present in the dynamics. In this regime, we find two approximations of the stationary measure. One works well for rapid switching, the other for slowly fluctuating environments.

Highlights

  • Evolutionary dynamics describes the change of populations over time subject to spontaneous mutation, selection and other random events [1,2]

  • For the case in which mutations occur during the dynamics, as described in §6, we explore how the stationary distribution of the population changes in fluctuating environments

  • The constant parameter b . 0 is the so-called intensity of selection. Based on this definition of fitness, we model the evolutionary dynamics by the update rules of the Moran process [34,44], which has been widely used in evolutionary game theory [2,28,45]

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Summary

Introduction

Evolutionary dynamics describes the change of populations over time subject to spontaneous mutation, selection and other random events [1,2]. It is largely an open question how complex interactions between phenotypes together with spontaneous changes in the environment influence the evolutionary dynamics. Analytical results for the probabilities of a single mutant to reach fixation have been obtained [26,27,28,29] Most of this existing work focuses on games played in a fixed environment; the underlying payoff matrix itself remains unchanged in time. For the case in which mutations occur during the dynamics, as described in §6, we explore how the stationary distribution of the population changes in fluctuating environments.

Mathematical model
Birth – death dynamics
Fluctuating environment
Fixation probability
Unconditional fixation time
Conditional fixation time
Continuous-time model
Fixation times
Switching between two environments
Effective description for fast switching
Evolutionary games
Switching between coexistence and coordination games
Sample trajectory of the dynamics
Fixation probability and conditional fixation time
Interpretation
Mutations and stationary distributions
Results
Summary and conclusion
Full Text
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