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When Does Frequency-Independent Selection Maintain Genetic Variation?

Sebastian Novak1, Nicholas H Barton2

  • 1Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria sebastian.novak@ist.ac.at.

Genetics
|August 12, 2017
PubMed
Summary
This summary is machine-generated.

Frequency-independent selection typically reduces genetic variation. However, fluctuating selection can maintain genetic diversity by periodically altering linkage disequilibrium, challenging this view.

Keywords:
epistasisfluctuating selectionfrequency-independent selectiongenetic variationlinkage disequilibrium

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Area of Science:

  • Evolutionary Biology
  • Population Genetics

Background:

  • Frequency-independent selection is often presumed to decrease genetic variation.
  • Rigorous evidence supporting this assumption, especially under fluctuating selection, is limited.

Purpose of the Study:

  • To investigate whether frequency-independent selection can maintain genetic polymorphism without additional evolutionary mechanisms.
  • To clarify the role of fluctuating selection in preserving genetic diversity.

Main Methods:

  • Theoretical analysis of frequency-independent selection at the allele level in haploid populations.
  • Introduction of a diallelic two-locus model to examine linkage disequilibrium dynamics.
  • Numerical calculations to assess the stability of equilibria under weak selection and recombination.

Main Results:

  • Constant frequency-independent selection, even with epistasis, eliminates genetic variation under linkage equilibrium.
  • Strong linkage disequilibrium can arise when selection and recombination are weak and of similar magnitude.
  • Fluctuating frequency-independent selection can maintain stable polymorphism if linkage disequilibrium changes sign periodically.

Conclusions:

  • Constant frequency-independent selection generally reduces genetic variation.
  • Time-varying frequency-independent selection offers a potential mechanism for maintaining genetic polymorphism.
  • The interplay between selection, recombination, and linkage disequilibrium is crucial for understanding genetic variation maintenance.