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The consequences of fluctuating selection for isozyme polymorphisms in Daphnia
1Department of Ecology, Ethology, and Evolution, Shelford Vivarium, University of Illinois, Champaign, Illinois 61820.
Genetics
|April 1, 1987
Summary
Allele frequencies in Daphnia populations suggest quasi-neutrality, with fluctuating selection explaining gene distribution. This research resolves puzzles in Daphnia population genetics without needing genetic drift or diversifying selection.
Area of Science:
- Evolutionary Biology
- Population Genetics
- Molecular Ecology
Background:
- Daphnia populations exhibit complex gene frequency dynamics.
- Understanding selection pressures is crucial for explaining genetic variation in natural populations.
Purpose of the Study:
- To analyze temporal allele frequency data in Daphnia.
- To estimate selection coefficients and their variances in asexual and sexual phases.
- To model the impact of fluctuating selection on gene frequency distributions.
Main Methods:
- Analysis of temporal allele frequency sequences in natural Daphnia populations.
- Estimation of mean and variance of selection coefficients.
- Application of empirical results to population genetic models.
Main Results:
- Enzyme loci alleles in Daphnia are generally quasi-neutral.
- Selection coefficients show significant variation but average near zero.
- Fluctuating selection significantly impacts spatial and temporal gene frequency distributions.
Conclusions:
- Fluctuating selection provides a potential explanation for observed gene frequency patterns in Daphnia.
- Genetic drift and diversifying selection are not required to explain local gene frequency diversification.
- The study offers insights into previously puzzling aspects of Daphnia population genetics.
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