Evolution of evolvability in rapidly adapting populations

Area of Science:

• Evolutionary biology
• Genetics
• Microbial evolution

Background:

• Mutations impact organism fitness and future mutation dynamics.
• Evolvability modifiers are observed in microbial populations but poorly understood theoretically.

Purpose of the Study:

• Develop a mathematical framework to predict the selection of genetic variants modifying mutation rates and benefits.
• Analyze the influence of population size and mutation diversity on these modifiers.

Main Methods:

• Mathematical modeling of genetic variants in linked genomic regions.
• Derivation of analytical expressions for fixation probabilities.
• Analysis of selection dynamics under varying population sizes and mutation diversity.

Main Results:

• Competition between linked mutations enhances selection for beneficial evolvability modifiers.
• Modifiers increasing future mutation benefits can fix despite direct fitness costs.
• Even small direct benefits can lead to the fixation of maladaptive modifiers.

Conclusions:

• Evolvability modifiers play a significant role in the long-term success of genetic variants in rapidly evolving microbes.
• Population size and mutation diversity are key factors in the selection of evolvability modifiers.
• The interplay between direct fitness effects and indirect effects on future mutations shapes evolutionary trajectories.