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Chromosome inversions, local adaptation and speciation
Mark Kirkpatrick1, Nick Barton
1Section of Integrative Biology, University of Texas, Austin 78712, USA. kirkp@mail.utexas.edu
Genetics
|October 6, 2005
Summary
New inversions can evolve and spread by capturing locally adapted genes during population hybridization. This mechanism explains fixed differences and common polymorphisms between species without needing drift or epistasis.
Area of Science:
- Evolutionary genetics
- Population genetics
Background:
- Inversions are common in natural populations and can harbor locally adapted alleles.
- Previous hypotheses for inversion evolution often require specific conditions like strong epistasis or drift.
Purpose of the Study:
- To investigate the evolution of inversions that capture locally adapted alleles in hybridizing or migrating populations.
- To propose a general mechanism for inversion spread and maintenance.
Main Methods:
- Theoretical modeling of inversion dynamics under gene flow.
- Analysis of factors influencing inversion frequency, including recombination suppression and selection.
Main Results:
- Inversions can spread and reach high frequencies by suppressing recombination between locally adapted alleles, even without epistasis or drift.
- Inversions can be stabilized at intermediate frequencies by capturing deleterious mutations, explaining polymorphisms.
- The mechanism can explain underdominant inversions and the mapping of adaptive loci to inversions.
Conclusions:
- Recombination suppression within inversions provides a powerful mechanism for local adaptation and divergence.
- This model offers a unifying explanation for various observed features of inversion systems in natural populations.