|Title||Testing for ancient admixture between closely related populations.|
|Publication Type||Journal Article|
|Year of Publication||2011|
|Authors||Durand, EY, Patterson, N, Reich, D, Slatkin, M|
|Journal||Molecular biology and evolution|
|Date Published||2011 Aug|
|Keywords||admixture, denisova, introgression, Neandertal DNA, theory|
One enduring question in evolutionary biology is the extent of archaic admixture in the genomes of present-day populations. In this paper, we present a test for ancient admixture that exploits the asymmetry in the frequencies of the two nonconcordant gene trees in a three-population tree. This test was first applied to detect interbreeding between Neandertals and modern humans. We derive the analytic expectation of a test statistic, called the D statistic, which is sensitive to asymmetry under alternative demographic scenarios. We show that the D statistic is insensitive to some demographic assumptions such as ancestral population sizes and requires only the assumption that the ancestral populations were randomly mating. An important aspect of D statistics is that they can be used to detect archaic admixture even when no archaic sample is available. We explore the effect of sequencing error on the false-positive rate of the test for admixture, and we show how to estimate the proportion of archaic ancestry in the genomes of present-day populations. We also investigate a model of subdivision in ancestral populations that can result in D statistics that indicate recent admixture.
|Alternate Journal||Mol. Biol. Evol.|
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