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Following the Dynamics of Structural Variants in Experimentally Evolved Populations
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Temporal variation in selection accelerates mutational decay by Muller's ratchet
Alison M Wardlaw1, Aneil F Agrawal
1Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada. alison.wardlaw@utoronto.ca
Genetics
|May 1, 2012
Summary
Temporal environmental changes accelerate Muller's ratchet, the accumulation of harmful mutations in asexual species. This process, especially with temporal autocorrelation, increases mutation rates and fitness decline, potentially explaining the rarity of asexual organisms.
Area of Science:
- Evolutionary Biology
- Population Genetics
Background:
- Asexual lineages face irreversible accumulation of deleterious mutations via Muller's ratchet.
- Previous models often overlooked temporal environmental heterogeneity's impact on ratchet rate.
Purpose of the Study:
- To investigate the effect of temporal environmental heterogeneity on Muller's ratchet.
- To analyze the role of conditional neutrality and varying selection strength.
Main Methods:
- Examined Muller's ratchet under conditions of temporal environmental variation.
- Incorporated conditional neutrality and fluctuating selection strengths.
Main Results:
- Temporal variation significantly increases mutation accumulation and fitness decline rates compared to constant selection.
- Temporal autocorrelation amplifies these effects, enabling the ratchet in large populations.
- The relationship between selection strength and fitness decline rate is altered, sometimes indefinitely increasing with selection.
Conclusions:
- Temporal environmental heterogeneity, particularly autocorrelation, accelerates Muller's ratchet.
- These findings offer a potential explanation for the limited diversity of asexual taxa.
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