Evolution of Microbial Growth Traits Under Serial Dilution

Area of Science:

• Microbial Evolution
• Population Dynamics
• Theoretical Biology

Background:

• Microbial populations evolve through selection on cellular traits.
• Key traits include lag time, growth rate, and yield.
• Serial-dilution experiments are common for studying microbial evolution.

Purpose of the Study:

• To investigate the evolution of lag time, growth rate, and yield in microbial populations.
• To model the dynamics of beneficial mutations under resource competition.
• To understand how experimental parameters influence adaptation speed.

Main Methods:

• Developed a minimal model of microbial population dynamics.
• Simulated laboratory evolution experiments with serial dilutions.
• Analyzed the fixation probability of beneficial mutations.

Main Results:

• Fixation probability depends on growth rate and lag time, influenced by the dilution factor.
• Yield is not under direct selection in this model.
• Adaptation speeds are dependent on experimental parameters and mutation supply.
• Correlations between traits can emerge even with uncorrelated mutations.

Conclusions:

• The dilution factor critically shapes selection pressures on microbial traits.
• Yield adaptation is not directly driven by selection for increased resource conversion.
• Understanding trait covariation is key to predicting evolutionary trajectories.
• Results offer guidance for designing and interpreting microbial evolution experiments.