HOW MUCH HERITABLE VARIATION CAN BE MAINTAINED IN FINITE POPULATIONS BY MUTATION-SELECTION BALANCE?

Area of Science:

• Evolutionary genetics
• Population genetics
• Quantitative genetics

Background:

• Genetic variability is shaped by evolutionary forces like selection, mutation, recombination, and genetic drift.
• Understanding equilibrium genetic variance is crucial for predicting evolutionary trajectories.
• Previous models often relied on deterministic equations, limiting their applicability to stochastic processes.

Purpose of the Study:

• To investigate the combined effects of stabilizing selection, mutation, recombination, and genetic drift on genetic variability.
• To develop and validate a new formula for predicting equilibrium genetic variance in finite populations.
• To compare theoretical predictions with empirical heritability estimates from natural and laboratory populations.

Main Methods:

• A stochastic computer simulation based on the continuum-of-alleles model.
• Modeling evolution as a Markov process, avoiding deterministic equations.
• Derivation of a novel analytical formula for expected equilibrium genetic variance.

Main Results:

• The derived formula for expected equilibrium genetic variance closely approximates simulation results across tested parameter combinations.
• The simulation study validates analytical predictions regarding genetic variance.
• Heritability estimates (20-50%) are explained by mutation-selection balance under specific conditions.

Conclusions:

• The new formula provides a highly accurate prediction of equilibrium genetic variance.
• High heritability in stable environments suggests a mutation-selection balance, particularly with neutral traits or a large number of contributing genes.
• The findings offer insights into the genetic architecture of quantitative traits and their evolutionary stability.