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How is variation in fitness maintained?
1Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom.
Evolution; International Journal of Organic Evolution
|March 6, 2026
Summary
Evolutionary genetics faces a puzzle: how can substantial additive genetic variance in fitness persist? This study explores how genetic drift and fluctuating fitness can maintain this variance at loci under balancing selection.
Area of Science:
- Evolutionary genetics
- Population genetics
- Quantitative genetics
Background:
- The persistence of additive genetic variance in fitness is a fundamental problem in evolutionary biology.
- Balancing selection is known to maintain genetic diversity but typically reduces additive genetic variance.
Purpose of the Study:
- To investigate the impact of random genetic drift and temporal fluctuations in fitness on loci under balancing selection.
- To explore mechanisms by which substantial additive genetic variance can be maintained despite balancing selection.
Main Methods:
- Theoretical modeling of genetic drift and fluctuating selection.
- Analysis of loci maintained by balancing selection.
Main Results:
- Random genetic drift can cause loci under balancing selection to deviate from their selective equilibria.
- Temporal fluctuations in fitness, in conjunction with drift, can lead to the maintenance of substantial additive genetic variance.
Conclusions:
- Departures from selective equilibria, driven by drift and fitness fluctuations, offer a potential resolution to the paradox of persistent additive genetic variance in fitness.
- This theoretical framework provides insights into the maintenance of quantitative trait variation in natural populations.
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