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HYBRID ZONES WITH DOBZHANSKY-TYPE EPISTATIC SELECTION.
1Departments of Ecology and Evolutionary Biology and Mathematics, University of Tennessee, Knoxville, Tennessee, 37996-1300.
Summary
Dobzhansky-type epistatic selection creates strong barriers to neutral gene flow by maintaining allele frequency clines. These clines indicate selection, influencing population evolution and reproductive isolation.
Area of Science:
- Evolutionary Biology
- Population Genetics
Background:
- Dobzhansky's model proposes "clusters" of viable genotypes, allowing evolution along
- ridges
- of high fitness without crossing adaptive valleys.
- Recent work emphasizes Dobzhansky-type models as general properties of adaptive landscapes.
Purpose of the Study:
- To analyze allele frequency clines under Dobzhansky-type epistatic selection and migration.
- To determine if Dobzhansky-type selection can impede neutral gene flow.
- To identify cline properties indicative of Dobzhansky-type selection.
Main Methods:
- Analysis of allele frequency clines using rigorous techniques.
- Numerical simulations of Dobzhansky-type epistatic selection and migration.
- Focus on two diallelic loci with selected and neutral alleles.
Main Results:
- Dobzhansky-type epistatic selection effectively builds strong barriers to neutral gene flow.
- Clines in allele frequencies are maintained by a balance between migration and epistatic selection.
- Specific cline properties are identified as indicators of Dobzhansky-type selection.
Conclusions:
- Dobzhansky-type epistatic selection plays a significant role in shaping population genetic structure.
- This selection model can create substantial reproductive isolation by restricting gene flow.
- The study provides a method for detecting Dobzhansky-type selection in natural populations.
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