Genetics· 2026Q1
Mean fitness is maximized in small populations under stabilizing selection on highly polygenic traits
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- 2026year
Short summary
Mean fitness is maximized by a finite, often small, population size under stabilizing selection on highly polygenic traits when the total mutation rate (U) is sufficiently large (U > σ² / 4(VS + VE)).
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Key points
- Mean fitness is maximized by a finite population size under stabilizing selection on polygenic traits.
- This effect is pronounced when the total diploid mutation rate (U) is large.
- The condition for maximized mean fitness is U > σ² / 4(VS + VE).
- Predictions were validated using simulations.
AI-generated from the title and abstract; the full text is not read.
Abstract
Stabilizing selection commonly acts on complex traits that affect individual fitness. Here, we relate mean fitness under stabilizing selection to population size and trait architecture, using a simple application of theoretical predictions for the distribution of phenotypic values in a single-trait Gaussian stabilizing selection model. We show that mean fitness is maximized by a finite (often small) population size when the total diploid mutation rate U across trait-affecting loci is reasonably large. Namely, this occurs when U>σ24(VS+VE), where σ2 is the variance of the distribution of effect sizes of new mutations, VS determines the strength of stabilizing selection, and VE is the environmental variance. We validate these predictions using simulations and briefly discuss their implications for interpreting genetic load and adaptability in small populations.
The authors' abstract, as published at the source. Genetics, 2026 · DOI ↗
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Field: Genetics (Biochemistry, Genetics and Molecular Biology)
GeneticsBiochemistry, Genetics and Molecular Biology