The Point of No Return: Evolution of Excess Mutation Rate is Possible Even for Simple Mutation Models

TL;DR

This paper demonstrates that even in simple mutation models under constant selection, mutation rates can evolve upwards, challenging the common expectation that they will decrease, using diverse modeling approaches.

Contribution

It introduces a variety of mutation representations and shows that mutation rate evolution can be more complex than previously thought in simple models.

Findings

Upward mutation rate evolution is possible in simple models.

Different mutation representations influence evolutionary outcomes.

Mutation rate evolution can be more intricate than traditional models suggest.

Abstract

Under constant selection, each trait has a fixed fitness, and small mutation rates allow populations to efficiently exploit the optimal trait. Therefore it is reasonable to expect mutation rates will evolve downwards. However, we find this need not be the case, examining several models of mutation. While upwards evolution of mutation rate has been found with frequency or time dependent fitness, we demonstrate its possibility in a much simpler context. This work uses adaptive dynamics to study the evolution of mutation rate, and the replicator-mutator equation to model trait evolution. Our approach differs from previous studies by considering a wide variety of methods to represent mutation. We use a finite string approach inspired by genetics, as well as a model of local mutation on a discretization of the unit intervals, handling mutation beyond the endpoints in three ways. The main contribution of this work is a demonstration that the evolution of mutation rate can be significantly more complicated than what is usually expected in relatively simple models.