Quantifying selective pressures driving bacterial evolution using lineage analysis.

Area of Science:

• Evolutionary biology
• Microbiology
• Quantitative biology

Background:

• Organisms adapt to environments, but quantifying these strategies' benefits and population growth impacts is difficult.
• Understanding selective pressures is crucial for fields like antibiotic resistance research.

Purpose of the Study:

• To develop a quantitative method for measuring selective pressures on populations.
• To demonstrate the utility of lineage-based measurements in evolutionary studies.
• To analyze age-dependent selection in bacteria exposed to antibiotics.

Main Methods:

• Utilized a path-integral framework to analyze selection acting on lineages (life-histories).
• Applied the framework to *E. coli* under cyclical carbenicillin treatment.
• Showcased how lineage statistics from a single cell can recapitulate population-level pressures.

Main Results:

• Lineage-based measurements can quantify population-wide selective pressures.
• Age-dependent selection by carbenicillin on *E. coli* was characterized.
• A single surviving cell's lineage statistics can reflect population-wide evolutionary forces.

Conclusions:

• The lineage-based framework provides an efficient alternative to traditional methods for quantifying evolutionary pressures.
• This approach can be generalized to study various trait-specific selection pressures.
• The findings offer a powerful tool for understanding evolutionary dynamics, antibiotic resistance, and survival strategies.