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bioRxiv · 10.1101/071894

Evolution of Drift Robustness in Small Populations of Digital Organisms

Thomas LaBar·Christoph Adami
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Abstract

Most mutations are deleterious and cause a reduction in population fitness known as the mutational load. In small populations, weakened selection against slightly-deleterious mutations results in an additional fitness reduction. Many studies have established that populations can evolve a reduced mutational load by evolving mutational robustness, but it is uncertain whether small populations can evolve a reduced susceptibility to drift-related fitness declines. Here, using mathematical modeling and digital experimental evolution, we show that small populations do evolve a reduced vulnerability to drift, or \"drift robustness\". We find that, compared to genotypes from large populations, genotypes from small populations have a decreased likelihood of small-effect deleterious mutations, thus causing small-population genotypes to be drift-robust. We further show that drift robustness is not adaptive, but instead arises because small populations preferentially adapt to drift-robust fitness peaks. These results have implications for genome evolution in organisms with small population sizes.

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Thomas LaBar, Christoph Adami. 2016-08-27. Evolution of Drift Robustness in Small Populations of Digital Organisms. https://doi.org/10.1101/071894

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