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Updated: Jul 4, 2026

Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
The anomalous effects of biased mutation revisited: mean-optimum deviation and apparent directional selection under
Xu-Sheng Zhang1, William G Hill
1Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom. xu-sheng.zhang@ed.ac.uk
Abstract:
Empirical evidence indicates that the distribution of the effects of mutations on quantitative traits is not symmetric about zero. Under stabilizing selection in infinite populations with normally distributed mutant effects having a nonzero mean, Waxman and Peck showed that the deviation of the population mean from the optimum is expected to be small. We show by simulation that genetic drift, leptokurtosis of mutational effects, and pleiotropy can increase the mean-optimum deviation greatly, however, and that the apparent directional selection thereby caused can be substantial.
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