DNA水平自然选择作用的检测

上个世纪60年代,Kimura提出的“中性进化”假说使经典的达尔文自然选择学说遭遇了前所未有的挑战。但新近的研究表明：在DNA水平,越来越多的证据支持“自然选择”的进化理论。这些研究成果得益于近年来大量群体和基因组DNA数据的积累,以及理论群体遗传学的发展。在DNA水平检测选择作用是否存在的方法包括两大类：种内多态性检验和种间差异度检验。前者以Tajima(1989)提出的D检验为代表,后者大都基于“中性条件下,种内与种间进化速率一致”的原理。这些方法以中性假说作为零假设,结合统计检验方法分析DNA数据,被称为“中性检验”。这些方法对于解决一些有关进化的基础理论问题和人类遗传学及生物信息学的深入研究都具有重要意义。本文介绍几个应用广泛的检测方法,以使国内的读者了解它们的基本思路和操作方法。

Detecting Natural Selection at the DNA Level

In the 1960s,the neutral theory proposed by Kimura caused an unprecedented challenge to the classical Darwin s theory of natural selection.However,recent advances in evolutionary genetics have provided a great deal of evidence on the role played by natural selection at the DNA level.These progresses have been stemmed from the appearance of enormous DNA sequence data of populations and genomes as well as the development of theoretical population genetics.There are mainly two kinds of approaches to detect selection at the DNA level:intraspecific polymorphism tests and interspecific divergence tests.The former one is represented by Tajima s (1989) D test while the latter one is based on the principle that the intraspecific polymorphism should be consistent with the interspecific divergence under neutrality.These methods are usually called "neutrality tests" because the neutrality hypothesis is taken as the null hypothesis in the tests.They are important tools not only in solving the basic theoretical questions in evolutionary biology but also in interpreting data and results obtained in the studies of human genetics and bioinformatics.In this paper,we shall review the progresses in detecting natural selection at the DNA sequence level and introduce the basis and application of several widely used tests.