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THE PROBABILITY OF FIXATION OF A NEW KARYOTYPE IN A CONTINUOUS POPULATION.
1Department of Genetics and Biometry, University College, 4, Stephenson Way, London, NW1 2HE, UK.
Summary
High migration in large populations reduces chromosome rearrangement fixation probability. In contrast, neighborhood size significantly impacts fixation in large, structured populations, even with strong selection.
Area of Science:
- Population genetics
- Evolutionary biology
- Genomics
Background:
- Understanding chromosome rearrangement fixation is key to evolutionary dynamics.
- Subdivided populations and migration patterns influence genetic drift and selection.
Purpose of the Study:
- To investigate chromosome rearrangement fixation probability in large, highly migratory, and subdivided populations.
- To analyze the impact of migration rates and population structure on fixation probability.
Main Methods:
- Mathematical modeling of chromosome rearrangement fixation.
- Analysis in two-deme, one-dimensional, and two-dimensional population structures.
- Focus on the limit of high migration relative to selection (m ≫ s).
Main Results:
- In two-deme systems, high migration significantly reduces fixation probability, mimicking a larger single population.
- In large, multi-deme (array) populations, fixation probability depends on neighborhood size (Nb), not just migration.
- Appreciable fixation probabilities are observed even with strong selection and gene flow in structured populations.
Conclusions:
- Migration's effect on fixation probability is complex and depends on population structure.
- Neighborhood size is a critical factor in determining fixation probability in large, subdivided populations.
- Results offer insights comparable to models of polygenic characters under disruptive selection.
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