Plasmid

Evolutionary biology

Biology

Gene

Ecology

Experimental evolution

Genetics

Trends in Microbiology

The 'plasmid paradox' arises because, although plasmids are common features of bacterial genomes, theoretically they should not exist: rates of conjugation were believed insufficient to allow plasmids to persist by infectious transmission, whereas the costs of plasmid maintenance meant that plasmids should be purged by negative selection regardless of whether they encoded beneficial accessory traits because these traits should eventually be captured by the chromosome, enabling the loss of the redundant plasmid.

Ecological and evolutionary solutions to the plasmid paradox