A geological timescale for bacterial evolution and oxygen adaptation.

Area of Science:

• Microbial evolution
• Geochemistry
• Paleontology

Background:

• Microbial life's fossil record is sparse, limiting understanding of deep-time evolution.
• Bacterial metabolism left geochemical signatures, notably the Great Oxidation Event (GOE).

Purpose of the Study:

• To infer ancestral bacterial transitions to aerobic lifestyles using machine learning and phylogenetic reconciliation.
• To link these transitions to the GOE for calibrating the bacterial time tree.

Main Methods:

• Machine learning algorithms were employed.
• Phylogenetic reconciliation techniques were utilized.
• Geochemical data, particularly related to the GOE, were integrated.

Main Results:

• Bacterial phyla diversity traces back to the Archaean and Proterozoic eons.
• Most bacterial phyla were ancestrally anaerobic, adopting aerobic lifestyles post-GOE.
• The cyanobacterial ancestor likely predated the GOE with aerobic metabolism.

Conclusions:

• The study provides insights into the evolutionary history of bacterial metabolisms.
• The GOE played a crucial role in shaping bacterial aerobic lifestyles.
• Early aerobic metabolism in cyanobacteria may have been a precursor to oxygenic photosynthesis.