Biological evolution through mutation, selection, and drift: An introductory review

TL;DR

This review explores how mutation, selection, and genetic drift influence biological evolution, emphasizing recent models of mutational degradation, error thresholds, Muller's ratchet, and mutational meltdowns, aiming to connect biological and physical perspectives.

Contribution

It provides a comprehensive overview of population genetics models and recent developments in mutational degradation phenomena, bridging biology and physics.

Findings

Error thresholds limit mutation rates controlled by selection

Muller's ratchet describes stochastic accumulation of deleterious mutations

Mutational meltdowns lead to population extinction under certain conditions

Abstract

Motivated by present activities in (statistical) physics directed towards biological evolution, we review the interplay of three evolutionary forces: mutation, selection, and genetic drift. The review addresses itself to physicists and intends to bridge the gap between the biological and the physical literature. We first clarify the terminology and recapitulate the basic models of population genetics, which describe the evolution of the composition of a population under the joint action of the various evolutionary forces. Building on these foundations, we specify the ingredients explicitly, namely, the various mutation models and fitness landscapes. We then review recent developments concerning models of mutational degradation. These predict upper limits for the mutation rate above which mutation can no longer be controlled by selection, the most important phenomena being error thresholds, Muller's ratchet, and mutational meltdowns. Error thresholds are deterministic phenomena, whereas Muller's ratchet requires the stochastic component brought about by finite population size. Mutational meltdowns additionally rely on an explicit model of population dynamics, and describe the extinction of populations. Special emphasis is put on the mutual relationship between these phenomena. Finally, a few connections with the process of molecular evolution are established.