On a test of Depaulis and Veuille.
نویسندگان
چکیده
In a recent letter to this journal, Depaulis and Veuille (1998) discussed two possible tests of neutrality, the ‘‘haplotype number test’’ and the ‘‘haplotype diversity test.’’ They present in their tables 1 and 2 means and percentage points of the distribution of the number Kn of haplotypes and the sample heterozygosity Hn 5 1 2 , where p1, . . . , are the relative frequenK 2 n S p p i51 i Kn cies of those haplotypes in a sample of size n for different values of the number of segregating sites s observed in the data. They assume a neutral infinitelymany-sites model of mutation with no recombination. These percentage points were found by repeatedly simulating a random coalescent tree with n tips, randomly distributing s mutations on the tree, and calculating the observed values of Kn and Hn. See Hudson (1990) for a description of how such simulations can be performed. Depaulis and Veuille’s (1998) procedure produces observations whose distribution is independent of the underlying neutral mutation rate u. The authors present the method as though the resulting simulated values had the conditional distribution of Kn and Hn given Sn 5 s, respectively. However, this is not true, as the following argument shows. Denote the coalescent tree by L and the coalescence times by T 5 (Tn, . . . , T2), so that Tj is the time for which there are j distinct ancestors in the tree L. We see that for mutation rate u, the conditional distribution of (Kn, Hn) given Sn 5 s can be represented as
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ورودعنوان ژورنال:
- Molecular biology and evolution
دوره 18 6 شماره
صفحات -
تاریخ انتشار 2001