Genome structure and the benefit of sex

Watson, Richard, Weinreich, Daniel M. and Wakeley, John (2011) Genome structure and the benefit of sex. Evolution, 65, (2), 523-536. (doi:10.1111/j.1558-5646.2010.01144.x). (PMID:21029076).


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We examine the behaviour of sexual and asexual populations in modular multi-peaked fitness landscapes and show that sexuals can systematically reach different, higher-fitness adaptive peaks than asexuals. Whereas asexuals must move against selection to escape local optima, sexuals reach higher fitness peaks reliably because they create specific genetic variants that ‘skip over’ fitness valleys, moving from peak to peak in the fitness landscape. This occurs because recombination can supply combinations of mutations in functional composites or ‘modules’, that may include individually deleterious mutations. Thus when a beneficial module is substituted for another less-fit module by sexual recombination it provides a genetic variant that would require either several specific simultaneous mutations in an asexual population or a sequence of individual mutations some of which would be selected against. This effect requires modular genomes, such that subsets of strongly epistatic mutations are tightly physically linked. We argue that such a structure is provided simply by virtue of the fact that genomes contain many genes each containing many strongly epistatic nucleotides. We briefly discuss the connections with ‘building blocks’ in the evolutionary computation literature. We conclude that there are conditions where sexuals can systematically evolve high-fitness genotypes that are essentially unevolvable for asexuals.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1111/j.1558-5646.2010.01144.x
ISSNs: 0014-3820 (print)
1558-5646 (electronic)
Keywords: epistasis, models/simulations, molecular evolution, population genetics, sex
Subjects: Q Science > QH Natural history > QH426 Genetics
Divisions : Faculty of Physical Sciences and Engineering > Electronics and Computer Science > Agents, Interactions & Complexity
ePrint ID: 271052
Accepted Date and Publication Date:
February 2011Published
5 November 2010Made publicly available
Date Deposited: 10 May 2010 15:47
Last Modified: 31 Mar 2016 14:18
Further Information:Google Scholar

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