Molecular and Genome Evolution of Prokaryotic Plasmids

Introduction

Plasmids are autonomously replicating extra-chromosomal elements that play a major role in prokaryote ecology and evolution. The study of plasmid evolution has so far focused mostly on their biodiversity and effect on their host ecology and evolution. Nonetheless, the fundamentals of plasmid genome evolution remain to a large extent uncharted territory.

Host Interaction

Plasmids reside within a host cell that supplies their environmental, energetic, and metabolic requirements. Consequently, natural selection operates on plasmids in two hierarchical levels:

1. The plasmid replication and inheritance within the host cell.
2. The host fitness within the population.

Studying the determinants of plasmid evolutionary success thus requires the expansion of classic population genetics theory to populations of plasmids within bacterial cells.

Project Aim

The overarching aim of pMolEvol is to create a novel unified framework for plasmid molecular and genome evolution. This includes:

1. Quantifying the effect of multilevel drift and selection on plasmid genetic diversity.
2. Supplying a framework for quantification of plasmid fitness and its effect on plasmid evolution.
3. Characterizing patterns and rates of plasmid genome evolution.

Methodology

Our conceptual framework will be based on empirical data from plasmid evolution experiments and reconstruction of past events from genomic information. The conceptually novel measures and approaches developed in pMolEvol open up avenues for the extension of classic population genetic theory to prokaryotic organisms.

Broader Implications

Across all domains of life, genetic information is stored, replicated, and translated by similar mechanisms. Focusing on plasmids, we aim to uncover the general principles that govern the evolution of autonomously replicating genetic elements.

Conclusion

Our ultimate goal is to describe plasmid evolution from emergence to extinction.