Evolution under Stochastic Transmission: Mutation-rate Modifiers

Area of Science:

• Population genetics
• Evolutionary biology
• Theoretical biology

Background:

• Evolutionary models often fix genetic transmission, focusing on selection variation.
• Stochasticity in transmission itself is less explored but crucial for understanding evolution.
• A neutral modifier locus controlling mutation rates linked to a selected locus is a common model.

Purpose of the Study:

• To investigate the impact of stochasticity in genetic transmission on evolutionary dynamics.
• To determine if random fluctuations in mutation rates alter the predictions of the Reduction Principle.
• To explore how temporal mutation rate distributions and recombination affect modifier allele invasion.

Main Methods:

• Mathematical modeling of a selected locus and a linked neutral modifier locus.
• Analysis of invasion dynamics for a rare modifier allele under fluctuating mutation rates.
• Comparison of stochastic transmission models with deterministic predictions (Reduction Principle).

Main Results:

• Under constant transmission, the Reduction Principle dictates invasion based on mean mutation rates.
• Stochastic transmission, with fluctuating mutation rates, decouples invasion from mean rates.
• Invasion success depends on mutation rate distribution, selection strength, and recombination rate.

Conclusions:

• Stochastic transmission and recombination can change the direction of selection on modifier alleles.
• Deterministic predictions based on average mutation rates are insufficient in stochastic settings.
• The study highlights the importance of incorporating transmission stochasticity into evolutionary models.