Quantifying the Slightly Deleterious Mutation Model of Molecular Evolution

Eyre-Walker, Adam, Keightley, Peter D, Smith, Nick G C and Gaffney, Daniel (2002) Quantifying the Slightly Deleterious Mutation Model of Molecular Evolution. Molecular Biology and Evolution, 19 (12). pp. 2142-2149. ISSN 0737-4038

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We have attempted to quantify the frequency and effects of slightly deleterious mutations (SDMs), those that have selective effects close to the reciprocal of the effective population size of a species, by comparing the level of selective constraint in protein-coding genes of related species that have different present-day effective population sizes. In our two comparisons, the species with the smaller effective population size showed lower constraint, implying that SDMs had become fixed. The fixation of SDMs was supported by the observation of a higher fraction of radical to conservative amino acid substitutions in species with smaller effective population sizes. The fraction of strongly deleterious mutations (which rarely become fixed) is >70% in most species. Only ~10% or fewer of mutations seem to behave as SDMs, but SDMs could comprise a substantial fraction of mutations in protein-coding genes that have a chance of becoming fixed between species.

Item Type: Article
Schools and Departments: School of Life Sciences > Evolution, Behaviour and Environment
Depositing User: Adam Eyre-Walker
Date Deposited: 06 Feb 2012 19:21
Last Modified: 20 Mar 2012 15:15
URI: http://sro.sussex.ac.uk/id/eprint/20246
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