Genetics: Role of mutation in fly-wing evolution.

Abstract

Analysis of wing variation within and between fly species reveals an unexpectedly slow evolutionary rate. Variations due to mutation and interspecific differences are similar, perhaps as a result of complex genetic interactions. See Letter p.447 Genetic mutation is the engine room of evolution. Without genetic mutation, genes would not vary, and natural selection would be powerless to act. But if genetic mutation provides the raw material for adaption, the extent to which mutation further constrains evolution over geological time is a matter of debate. Mutation rates are typically very small and are thought to be swamped by the amount of genetic divergence seen over evolutionary timescales. David Houle and colleagues present results that could be a fly in the ointment. Several thousand flies in fact. They examined the wings of more than 50,000 Drosophila and its close relatives to reveal an unexpected and strong positive relationship between mutation, genetic variation and evolutionary rate over the past 40 million years. This challenges several models of the role of mutation in evolution.