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Distortions in genealogies due to purifying selection
Lauren E Nicolaisen1, Michael M Desai
1Department of Organismic and Evolutionary Biology, Harvard University.
Molecular Biology and Evolution
|June 26, 2012
Summary
Purifying selection impacts molecular evolution by reducing genetic variation and distorting genealogies. This study models these effects using a time-dependent population size and mutation rate, simplifying analysis for populations under strong selection.
Area of Science:
- Evolutionary Biology
- Population Genetics
- Molecular Evolution
Background:
- Purifying selection significantly influences molecular evolution by decreasing genetic variation and altering genealogical structures.
- Existing models, like structured coalescent methods, describe these distortions but can be computationally intensive.
Purpose of the Study:
- To develop a simplified analytical framework for understanding molecular evolution under strong purifying selection.
- To approximate the effects of purifying selection using time-dependent population size and mutation rate parameters.
Main Methods:
- Extension of structured coalescent methods with the approximation of independent lineages in the strong selection regime.
- Derivation of analytical expressions for time-dependent effective population size (N(e)(t)) and mutation rate (U(e)(t)).
Main Results:
- Strong purifying selection can be accurately modeled as a neutral process with a time-varying effective population size and mutation rate.
- Analytical expressions for N(e)(t) and U(e)(t) were derived, simplifying the description of genealogical distortions.
Conclusions:
- The study provides a computationally tractable method for analyzing molecular evolution in populations under strong purifying selection.
- These findings enable the application of neutral inference methods to populations experiencing strong purifying selection, enhancing evolutionary studies.
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