Negative Selection and the Neutral Theory of Molecular Evolution

Abstract

AbstractNatural selection is not the only evolutionary “force” that can alter frequencies of genetic variants; random genetic drift (a sampling process) persistently changes the gene pool of populations, especially in small populations. Moreover, at the molecular level, negative selection is more prevalent than positive selection as deleterious mutations occur much more than do advantageous mutations. Motoo Kimura, a Japanese evolutionary geneticist, expanded on Darwinian evolution and formulated what is now called the neutral theory of molecular evolution. According to Kimura, patterns of molecular evolution are determined primarily by mutation, genetic drift, and negative selection. This chapter discusses the development of the neutral theory, and explains how it lays the foundation to produce tests used to detect positive selection and balancing selection. It also contains a discussion of hypothesis testing.