Microbial population dynamics and evolutionary outcomes under extreme energy limitation

Area of Science:

• Microbiology
• Ecology
• Evolutionary Biology

Background:

• Microorganisms often exist in energy-limited ecosystems, facing constraints on maintenance and reproduction.
• Understanding microbial persistence under resource scarcity is crucial for comprehending life's resilience.

Purpose of the Study:

• To investigate how heterotrophic bacteria persist in energy-limited conditions.
• To derive demographic parameters and understand survival mechanisms over extended periods.

Main Methods:

• Censused 100 populations of 21 heterotrophic bacterial taxa in a closed system for 1,000 days.
• Analyzed survival rates, extinction times, and evolutionary changes (mutations, selection).

Main Results:

• All but one taxon survived prolonged resource scarcity, with extinction times varying widely (10^0 to 10^5 years).
• Lifespan extension occurred via scavenging of dead cells as death rates declined.
• Populations evolved, acquiring hundreds of mutations indicative of purifying selection and adaptation.
• Distantly related bacteria exhibited consistent ecological and evolutionary responses to energy limitation.

Conclusions:

• Microbial persistence in energy-limited ecosystems is robust and predictable.
• Scavenging and evolution are key mechanisms enabling long-term survival.
• These dynamics contribute to the stability and resilience of microbial life.