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Evolution of the Mutational Process under Relaxed Selection in Caenorhabditis elegans
Ayush Shekhar Saxena1, Matthew P Salomon1,2, Chikako Matsuba1,2
1Department of Biology, University of Florida, Gainesville, FL.
Molecular Biology and Evolution
|November 17, 2018
Summary
The mutation rate in Caenorhabditis elegans evolves with mutation accumulation, showing increased total mutation rates and variations in base-substitution and indel rates influenced by genomic factors, not initial fitness.
Area of Science:
- Evolutionary Biology
- Genetics
- Molecular Biology
Background:
- The evolution of the mutational process is not well understood.
- Physiological condition and deleterious mutations can influence mutation rates.
Purpose of the Study:
- To test if the mutational process depends on the underlying mutation load.
- To investigate mutation rate variation in Caenorhabditis elegans.
Main Methods:
- Mutation accumulation (MA) lines of Caenorhabditis elegans were used.
- Lines with differing initial mutation loads underwent further mutation accumulation.
- Genomes of MA lines were sequenced to analyze mutation rates.
Main Results:
- Significant variation in base-substitution rates (µbs) was observed among lines.
- Indel rates were higher in high-fitness lines, while µbs was not affected by initial fitness.
- Base-substitution rate correlated with recombination and proximity to short tandem repeats.
- Total mutation rate increased in second-order MA lines, supporting the drift barrier model.
Conclusions:
- The mutational process is influenced by genomic features and evolves over time.
- Epistasis appears to be synergistic, as suggested by fitness estimates.
- The drift barrier model provides a framework for understanding mutation rate evolution.
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