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Genome structure and the benefit of sex

Genome structure and the benefit of sex
Genome structure and the benefit of sex
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.
epistasis, models/simulations, molecular evolution, population genetics, sex
0014-3820
523-536
Watson, Richard
ce199dfc-d5d4-4edf-bd7b-f9e224c96c75
Weinreich, Daniel M.
a5522cf4-5a31-4e13-9934-e3529fdd4d6f
Wakeley, John
a56e0da3-ddcc-4cdc-9d54-e652231160e5
Watson, Richard
ce199dfc-d5d4-4edf-bd7b-f9e224c96c75
Weinreich, Daniel M.
a5522cf4-5a31-4e13-9934-e3529fdd4d6f
Wakeley, John
a56e0da3-ddcc-4cdc-9d54-e652231160e5

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

Record type: Article

Abstract

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.

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e-pub ahead of print date: 5 November 2010
Published date: February 2011
Keywords: epistasis, models/simulations, molecular evolution, population genetics, sex
Organisations: Agents, Interactions & Complexity

Identifiers

Local EPrints ID: 271052
URI: http://eprints.soton.ac.uk/id/eprint/271052
ISSN: 0014-3820
PURE UUID: 70ad90bc-42c5-4414-a568-aac8d078cc3a

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Date deposited: 10 May 2010 15:47
Last modified: 18 Jul 2017 06:47

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Contributors

Author: Richard Watson
Author: Daniel M. Weinreich
Author: John Wakeley

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