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Stochastic patterns of polymorphism after a selective sweep over a subdivided population
1Division of EcoScience, Ewha Womans University, Seoul 120-750, Korea. yuseob@ewha.ac.kr
Genetics Research
|April 9, 2013
Summary
Population subdivision slows beneficial allele spread, altering genetic variation patterns. Simulations show minor shifts in frequency spectrum and linkage disequilibrium, but increased FST, complicating inference of mutation spread direction.
Area of Science:
- Population Genetics
- Evolutionary Biology
- Genomics
Background:
- Geographic population structure, modeled as interconnected demes, limits rapid spread of beneficial alleles.
- This subdivision modifies the hitchhiking effect on linked neutral genetic variation.
- Previous studies predicted characteristic polymorphism patterns during selective sweeps in subdivided populations but lacked stochastic detail.
Purpose of the Study:
- To investigate the stochastic patterns of neutral polymorphism following a selective sweep in a moderately subdivided population.
- To analyze the impact of population subdivision on frequency spectrum, linkage disequilibrium, and FST.
- To assess the feasibility of inferring beneficial mutation spread direction using heterozygosity gradients.
Main Methods:
- Novel individual-based forward-in-time simulation.
- Generation of multi-locus neutral polymorphism data.
- Analysis of frequency spectrum (Tajima's D), linkage disequilibrium, Wright's FST, and heterozygosity gradients.
Main Results:
- Population subdivision caused a slight shift in the frequency spectrum, making Tajima's D less negative than in panmictic populations.
- Linkage disequilibrium showed minimal change due to subdivision.
- Wright's FST increased significantly at closely linked neutral loci relative to unlinked loci.
- Heterozygosity gradient analysis revealed high variance, suggesting practical limitations for inferring spread direction.
Conclusions:
- Population subdivision moderately impacts genetic variation patterns after selective sweeps.
- While FST is sensitive to subdivision, inferring the direction of beneficial allele spread from heterozygosity gradients is challenging due to high variance.
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