Transitions to asexuality result in excess amino acid substitutions

Susanne Paland, Michael Lynch

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Abstract

Theory predicts that linkage between genetic loci reduces the efficiency of purifying selection. Because of the permanent linkage of all heritable genetic material, asexual lineages may be exceptionally prone to deleterious-mutation accumulation in both nuclear and organelle genes. Here, we show that the ratio of the rate of amino acid to silent substitution (Ka/Ks) in mitochondrial protein-coding genes is higher in obligately asexual lineages than in sexual lineages of the microcrustacean Daphnia pulex. Using a phylogeny-based approach to quantify the frequency of mutational-effect classes, we estimate that mitochondrial protein-coding genes in asexual lineages accumulate deleterious amino acid substitutions at four times the rate in sexual lineages. These results support the hypothesis that sexual reproduction plays a prominent role in reducing the mutational burden in populations.

Original languageEnglish (US)
Pages (from-to)990-992
Number of pages3
JournalScience
Volume311
Issue number5763
DOIs
StatePublished - Feb 17 2006
Externally publishedYes

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ASJC Scopus subject areas

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