Inferences of species phylogeny in relation to segregation of ancient polymorphisms.
Inferences of species phylogeny in relation to segregation of ancient polymorphisms.
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DOI：
10.1093/genetics/127.2.429
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发表时间：
1991-02
期刊：
影响因子：
3.3
通讯作者：
Chung-I Wu
中科院分区：
文献类型：
--
作者：
Chung-I Wu
利用遗传漂变条件下基因频率变化的标准公式，推导了由于古多态性分离而导致三个物种系统发育信息不正确的概率。这种可能性取决于物种形成时的多态性水平，通常是相当高的，除非两个物种形成事件在时间上相隔很远。如果来自多个基因座的系统发育数据是可用的，似然比检验可以用来拒绝零假设，支持最佳的系统发育。根据数据集，适当的零假设是三分法或另一种系统发育。给出了接受最佳系统发育所需的似然比。当基因座的数目很小（n小于15）时，通过精确枚举获得这些比率；当n较大时，通过渐近方法获得这些比率。一般来说，解决物种系统发育问题需要5个以上的基因座。
Standard formulas of gene frequency change under genetic drift are used to derive the probability of obtaining incorrect phylogenetic information for three species due to segregation of ancient polymorphisms. This probability depends upon the level of polymorphisms at the time of speciation and is generally quite high unless the two speciation events are far apart in time. If phylogenetic data from multiple loci are available, a likelihood ratio test can be used to reject the null hypothesis in favor of the best phylogeny. The appropriate null hypothesis is either a trichotomy or an alternative phylogeny, depending on the data set. The likelihood ratios required for accepting the best phylogeny are given. These ratios are obtained by exact enumeration when the number of loci is small (n less than 15) and by an asymptotic approach for larger n's. In general, more than five loci are needed to resolve the species phylogeny.