Molecular Evolution: A Brief Introduction

Abstract

Molecular evolution is an expansive and highly interdisciplinary field of research that investigates the evolution of biological molecules and molecular phenomena over time. A notable feature of the field is its ability to embrace and adapt to novel molecular methods, technology, and data while developing and applying a rigorous theoretical framework of population genetics to data interpretation. In the early days of molecular biology, as protein and DNA sequences began to accumulate, molecular evolutionary analyses contributed to the development of several fundamental concepts that remain impactful even after several decades. From preliminary comparisons of protein sequences from distantly related species emerged the idea of a constant molecular clock. In turn, this idea became one of the main inspirations for the neutral theory of molecular evolution, which provides the basis for widely used statistical approaches to test selection using molecular data, including genome sequences. The nearly neutral theory emphasizes that the evolutionary dynamics of many mutations are governed by genetic drift because their effects on fitness are borderline neutral, and this theory can explain many broad patterns of molecular evolution. As the field of molecular evolution embraces the so-called ‘omics’ era, these foundational ideas continue to provide guiding principles.