4. Neutral Evolution: Genetic Drift

Principles of Evolution, Ecology and Behavior (EEB 122)

Neutral evolution occurs when genes do not experience natural selection because they have no effect on reproductive success. Neutrality arises when mutations in an organism's genotype cause no change in its phenotype, or when changes in the genotype bring about changes in the phenotype that do not affect reproductive success. Because neutral genes do not change in any particular direction over time and simply "drift," thanks in part to the randomness of meiosis, they can be used as a sort of molecular clock to determine common ancestors or places in the phylogenetic tree of life.

00:00 - Chapter 1. Introduction
04:56 - Chapter 2. Genes and Amino Acid Changes Not Reflected in Phenotypes
14:29 - Chapter 3. Neutral Evolution in the History of Life
20:38 - Chapter 4. Mechanisms of Neutral or Random Evolution
35:28 - Chapter 5. The Molecular Clock of Neutral Evolution

Complete course materials are available at the Open Yale Courses website: http://open.yale.edu/courses

This course was recorded in Spring 2009.