Fig. 2.

Trait space depicting the potential realized fitness according to a plasmids vertical and horizontal transmission fitness. Its frequency in a local community declines if vertical transmission fitness is low, e.g. due to high rates of missegregation and plasmid costs, and if this cannot be compensated by horizontal transmission, e.g. conjugation. Both vertical and horizontal transmission fitness are not constant for a specific plasmid, but can be host-specific and change over time due to evolutionary modifications and spatio-temporal variations of environmental factors (see main text).