题目：Are certain types of mutation used preferentially in evolutionary change?
 
报告人：Mark Rausher
　　　　　　　　　　  Department of Biology, Duke University, Durham, North Carolina, U.S.A.
 
时间：2009年10月29日（星期四）上午10：00
 
地点：图资楼多功能厅
 
联系人：鲁迎青　 （tel：6441）
 
 
欢迎老师和同学们积极参加！
 
　　　　　　　　　　　　　　　　　　  系统与进化植物学国家重点实验室
 
附：
 
Abstract

An emerging debate in evolutionary biology concerns whether certain types of mutations (e.g. mutations in cis-regulatory regions, in transcription factors, in enzyme-coding genes) are fixed preferentially during adaptive evolution. Although there has been much speculation about the possible causes for such a bias, there has been little formal theory presented to test for these biases. I describe an approach that distinguishes 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. I then use this method to address several questions about evolutionary transitions involving repeated shifts in a single trait (flower color), as well as transitions between species across multiple traits. I show that fixation biases can be quite strong at all levels of comparison, likely due to differences in the magnitude of deleterious pleiotropy associated with alternative mutational categories. However, I also show that the scale of comparison greatly affects the interpretation of the results, which suggests that it may not be possible to formulate a general theory that encompasses all biological levels of organization. I conclude that preferential fixation of mutations likely is common in nature, but may need to be studied on a trait-by-trait basis.
 
Biography

Mark Rausher is Professor of Biology at Duke University. He was an undergraduate at the University of Chicago and obtained his Ph.D. in Ecology and Evolutionary Biology at Cornell University. His dissertation was on the ecology and evolution of the interaction between the pipevine swallowtail butterfly, Battus philenor, and its host plants. He did a brief postdoc at the University of Texas, Austin, working on butterfly behavior. His current research interests focus on the evolutionary genetics of ecologically important traits, particularly flower color, and the evolution of plant-pathogen interactions. He has been Editor-in-Chief of Evolution and of The American Naturalist.