Universality of weak selection

TL;DR

This paper investigates the universality of weak selection in evolutionary game theory, demonstrating that higher-order effects can be rescaled and identifying models that deviate from linear weak selection predictions.

Contribution

It extends the understanding of weak selection by analyzing higher-order effects and establishing their universal properties across different evolutionary models.

Findings

Higher-order expansions of fixation probability and time are universal.

Rescaling of selection intensity aligns different models' behaviors.

Certain models, like the one-third rule, violate linear weak selection predictions.

Abstract

Weak selection, which means a phenotype is slightly advantageous over another, is an important limiting case in evolutionary biology. Recently it has been introduced into evolutionary game theory. In evolutionary game dynamics, the probability to be imitated or to reproduce depends on the performance in a game. The influence of the game on the stochastic dynamics in finite populations is governed by the intensity of selection. In many models of both unstructured and structured populations, a key assumption allowing analytical calculations is weak selection, which means that all individuals perform approximately equally well. In the weak selection limit many different microscopic evolutionary models have the same or similar properties. How universal is weak selection for those microscopic evolutionary processes? We answer this question by investigating the fixation probability and the average fixation time not only up to linear, but also up to higher orders in selection intensity. We find universal higher order expansions, which allow a rescaling of the selection intensity. With this, we can identify specific models which violate (linear) weak selection results, such as the one--third rule of coordination games in finite but large populations.