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Related Experiment Video

Updated: Jun 25, 2026

Following the Dynamics of Structural Variants in Experimentally Evolved Populations

Following the Dynamics of Structural Variants in Experimentally Evolved Populations

Published on: February 3, 2023

Probing evolutionary repeatability: neutral and double changes and the predictability of evolutionary adaptation.

Scott William Roy¹

¹National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America. royscott@ncbi.nlm.nih.gov

|February 24, 2009

Summary

Evolutionary pathways to antibiotic resistance in Escherichia coli are highly constrained. Even with relaxed assumptions, the evolution of cefotaxime-resistant beta-lactamase proteins remains remarkably repeatable.

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Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli

Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli

Published on: August 18, 2023

Area of Science:

Evolutionary biology
Microbiology
Genetics

Background:

Investigates the evolution of Escherichia coli (E. coli) under antibiotic pressure.
Examines the role of mutations in the beta-lactamase gene conferring cefotaxime resistance.
Highlights the complex fitness landscape and constrained evolutionary pathways previously observed.

Purpose of the Study:

To further explore and analyze the evolutionary pathways to antibiotic resistance using existing data.
To assess the impact of neutral and multiple mutations on accessible evolutionary pathways.
To introduce and evaluate the metric of 'repeatability' in evolutionary trajectories.

Main Methods:

Re-analyzed data on five mutations in the beta-lactamase gene of E. coli.
Calculated the number of accessible evolutionary pathways under different mutation scenarios (neutral, double mutations).
Introduced and applied the 'repeatability' metric to assess pathway consistency.

Main Results:

Allowing neutral mutations increased accessible pathways from 27 to 629.
Allowing simultaneous mutations significantly increased pathway numbers, reaching 4800 with multiple pairs.
Evolutionary repeatability was found to be less affected by neutral or multiple mutations compared to the total number of pathways.

Conclusions:

The study probes the range of conceivable evolutionary pathways.
Even with relaxed assumptions, evolution towards cefotaxime-resistant beta-lactamase proteins is highly repeatable.
Findings contribute to understanding the predictability of evolutionary trajectories.