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Junk ain't what junk does: neutral alleles in a selected context
1Section of Evolution and Ecology, University of California, Davis 95616, USA. jhgillespie@ucdavis.edu
Gene
|February 14, 1998
Summary
Linked selection significantly impacts molecular variation and effective population size. Four variation-reducing models studied distort neutral frequency spectra similarly, complicating model inference and hindering the use of mutation associations for identifying linked selection.
Area of Science:
- Population genetics
- Molecular evolution
- Genomics
Background:
- Linked selection influences molecular variation at neutral loci.
- Understanding these effects is crucial for interpreting genetic diversity patterns.
- Previous studies have explored various models of linked selection.
Purpose of the Study:
- To simulate and analyze the effects of different linked selection models on neutral genetic variation.
- To assess the utility of frequency spectrum distortions and mutation associations for inferring linked selection.
- To investigate the impact of linked selection on the effective population size of neutral loci.
Main Methods:
- Computer simulations of six linked selection models.
- Analysis of molecular variation at a neutral locus.
- Examination of the neutral frequency spectrum.
- Investigation of non-random associations between mutations at two linked neutral loci.
Main Results:
- Four of the six models reduced molecular variation at the neutral locus.
- These four models distorted the neutral frequency spectrum in similar, indistinguishable ways.
- Non-random associations between mutations at linked neutral loci were not useful for inferring linked selection.
- Linked selection profoundly affected the effective population size, making it independent of actual population size in two models.
Conclusions:
- Distinguishing between different linked selection models is challenging due to similar distortions in the neutral frequency spectrum.
- Associated mutations at neutral loci do not reliably indicate the type of linked selection.
- Linked selection can drastically alter effective population size, decoupling it from census population size.
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