Neutrality and Selection in Molecular Evolution: Statistical Tests


Whether a locus evolves neutrally or under the influence of natural selection is of great interest in molecular evolutionary study. Statistical tests can be used to test if the observed polymorphisms in a DNA sample are consistent with the prediction of neutral evolution.

Keywords: neutrality test; natural selection; coalescent theory; DNA polymorphism

Figure 1.

A schematic relationship between two samples from two species diverged T generations ago. Circles and squares represent mutations that lead to within‐sample polymorphisms and between‐sample polymorphisms, respectively. t = (t2, t3) where t2 and t3 are time lengths between successive branching events within a sample, commonly known as the coalescent time. The common ancestral sequences of the two samples do not coalesce at T generations ago because the common ancestral population was polymorphic.

Figure 2.

An example of genealogy of six sequences with five mutations, three of which are of size 1 (external mutations), one of size 2 and one of size 4.



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Further Reading

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Fu, Yun‐Xin(Apr 2001) Neutrality and Selection in Molecular Evolution: Statistical Tests. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0001809]