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Macroevolution of plasmids: a model for plasmid speciation
1Zoology Department, University of Massachusetts, Amherst 01003.
Journal of Theoretical Biology
|November 7, 1992
Summary
A novel evolutionary model proposes that plasmid cointegrates drive plasmid speciation by allowing rep gene mutations. This process may explain genome evolution in bacteria and eukaryotes.
Area of Science:
- Evolutionary biology
- Microbial genetics
- Molecular biology
Background:
- Plasmid incompatibility groups are crucial for plasmid diversity.
- Plasmid cointegrates, formed from two compatible plasmids, are known but their evolutionary role is unclear.
Purpose of the Study:
- To propose a new evolutionary model for plasmid diversification (plasmid speciation).
- To investigate the role of plasmid cointegrates in macroevolution.
Main Methods:
- Hypothesizing a relaxed selection on rep genes within plasmid cointegrates.
- Analyzing evidence from naturally occurring multi-replicon plasmids.
- Reviewing experimental studies on plasmid cointegrate formation.
Main Results:
- Plasmid cointegrates allow rep genes to accumulate mutations, potentially altering incompatibility specificity.
- Multi-replicon plasmids are common, supporting the model.
- Experimental data on cointegrate formation align with the hypothesis.
Conclusions:
- Plasmid cointegrates are a significant driver of plasmid macroevolution and speciation.
- The model offers a potential evolutionary scenario for bacterial and eukaryotic genome origins.
- Plasmids and viruses may play a role in this broader evolutionary picture.