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      Bayes estimation of species divergence times and ancestral population sizes using DNA sequences from multiple loci.

      1 ,
      Genetics
      Oxford University Press (OUP)

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          Abstract

          The effective population sizes of ancestral as well as modern species are important parameters in models of population genetics and human evolution. The commonly used method for estimating ancestral population sizes, based on counting mismatches between the species tree and the inferred gene trees, is highly biased as it ignores uncertainties in gene tree reconstruction. In this article, we develop a Bayes method for simultaneous estimation of the species divergence times and current and ancestral population sizes. The method uses DNA sequence data from multiple loci and extracts information about conflicts among gene tree topologies and coalescent times to estimate ancestral population sizes. The topology of the species tree is assumed known. A Markov chain Monte Carlo algorithm is implemented to integrate over uncertain gene trees and branch lengths (or coalescence times) at each locus as well as species divergence times. The method can handle any species tree and allows different numbers of sequences at different loci. We apply the method to published noncoding DNA sequences from the human and the great apes. There are strong correlations between posterior estimates of speciation times and ancestral population sizes. With the use of an informative prior for the human-chimpanzee divergence date, the population size of the common ancestor of the two species is estimated to be approximately 20,000, with a 95% credibility interval (8000, 40,000). Our estimates, however, are affected by model assumptions as well as data quality. We suggest that reliable estimates have yet to await more data and more realistic models.

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          Author and article information

          Journal
          Genetics
          Genetics
          Oxford University Press (OUP)
          0016-6731
          0016-6731
          Aug 2003
          : 164
          : 4
          Affiliations
          [1 ] Department of Medical Genetics, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
          Article
          10.1093/genetics/164.4.1645
          1462670
          12930768
          64b5393e-b43e-41e5-9601-20597944d785
          History

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