Nearly neutral theory of molecular evolution

<p>The nearly neutral theory of molecular evolution is a modification of the <a href="/facts/Neutral_theory_of_molecular_evolution/vbAqP1cL">neutral theory of molecular evolution</a> that accounts for the fact that not all <a href="/facts/Mutation/Ee4NnWbY">mutations</a> are either so deleterious such that they can be ignored, or else neutral. Slightly deleterious mutations are reliably purged only when their <a href="/facts/Selection_coefficient/PfFtFl7F">selection coefficient</a> are greater than one divided by the <a href="/facts/Effective_population_size/WUP93ad1">effective population size</a>. In larger populations, a higher proportion of mutations exceed this threshold for which <a href="/facts/Genetic_drift/lvoEEctX">genetic drift</a> cannot overpower selection, leading to fewer <a href="/facts/Fixation_(population_genetics)/wDJzlUq7">fixation</a> events and so slower molecular evolution.
</p><p>The nearly neutral theory was proposed by <a href="/facts/Tomoko_Ohta/NWKQIhjx">Tomoko Ohta</a> in 1973. The population-size-dependent threshold for purging mutations has been called the "drift barrier" by <a href="/facts/Michael_Lynch_(geneticist)/9C7UDC8r">Michael Lynch</a>, and used to explain differences in genomic architecture among species.
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Nearly neutral theory of molecular evolution open-in-new

Nearly neutral theory of molecular evolution