Characterization of controllable mutator strains

The interplay between environmental selection and available variation within a population are central in the adaptation of populations to changing environments, for seemingly all levels of complexity in life. In order to investigate properties and mode of actions of the two counterplayers, more and more studies have started to conduct experiments, that expose populations to different, non-optimal conditions and describe changes in phenotypic traits and genotypes observed. Whereas the extrinsic selection regimes surrounding the populations can easily be changed at will by the investigators and hereby serves the elucidation of the properties of selection, modifying the intrinsic genetic variation of the individuals remains challenging and less of an experimental subject so far. In order to investigate mechanisms that cause genetic mutations, we constructed bacterial strains, that harbour mutator genes on plasmids with an inducible expression system. We present results of the characterization of the mutator strains, as a first step towards understanding mutation mechanisms and their influence on standing genetic variation and subsequent adaptation, in order to complement the investigations on selection for a full picture of the driving forces in evolution.