Abiotic Gene Transfer: Rare or Rampant?

Area of Science:

• Evolutionary Biology
• Microbiology
• Genetics

Background:

• Horizontal gene transfer (HGT) is crucial for evolution and genetic diversity.
• Five biotic HGT mechanisms in prokaryotes are known, but their completeness and the origins of HGT remain unclear.

Purpose of the Study:

• To explore potential abiotic HGT mechanisms in microorganisms, both currently and throughout evolutionary history.
• To estimate the rates and significance of these abiotic mechanisms compared to biotic ones.

Main Methods:

• Investigated laboratory techniques (freeze-thaw, agitation, electroporation) as analogues for natural abiotic HGT.
• Estimated rates of microbial exposure to these natural phenomena.
• Assessed the yield of viable transformants for different mechanisms.

Main Results:

• Identified freeze-and-thaw, sand agitation, and lightning-triggered electroporation as plausible abiotic HGT mechanisms.
• Estimated microbial exposure rates: 10^24 (freeze-thaw), 10^19 (sand agitation), 10^17 (lightning electroporation) per year.
• Electroporation yielded the highest transformant viability, suggesting lightning-triggered transformation may be favored.

Conclusions:

• Abiotic HGT, especially lightning-induced electroporation, could be a significant factor in microbial evolution.
• Further research is needed to refine rate estimates and understand the interplay between biotic and abiotic HGT.