POPULATION GENETICS, PLEIOTROPY, AND THE PREFERENTIAL FIXATION OF MUTATIONS DURING ADAPTIVE EVOLUTION
Version of Record online: 5 NOV 2010
© 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.
Volume 65, Issue 3, pages 629–642, March 2011
How to Cite
Streisfeld, M. A. and Rausher, M. D. (2011), POPULATION GENETICS, PLEIOTROPY, AND THE PREFERENTIAL FIXATION OF MUTATIONS DURING ADAPTIVE EVOLUTION. Evolution, 65: 629–642. doi: 10.1111/j.1558-5646.2010.01165.x
- Issue online: 1 MAR 2011
- Version of Record online: 5 NOV 2010
- Received November 13, 2009, Accepted September 29, 2010
- flower color;
- population genetics
Ongoing debate centers on whether certain types of mutations are fixed preferentially during adaptive evolution. Although there has been much discussion, no quantitative framework currently exists to test for these biases. Here, we describe a method for distinguishing between the two processes that likely account for biased rates of substitution: variation in mutation rates and variation in the probability that a mutation becomes fixed once it arises. We then use this approach to examine the type and magnitude of these biases during evolutionary transitions across multiple scales: those involving repeated origins of individual traits (flower color change), and transitions involving broad suites of traits (morphological and physiological trait evolution in plants and animals). We show that fixation biases can be strong at both levels of comparison, likely due to differences in the magnitude of deleterious pleiotropy associated with alternative mutation categories. However, we also show that the scale at which these comparisons are made greatly influences the results, as broad comparisons that simultaneously analyze mutliple traits obscure heterogeneity in the direction and magnitude of these biases. We conclude that preferential fixation of mutations likely is common in nature, but should be studied on a trait-by-trait basis.