Schematics of the experimental evolution strategies. Rounds of directed size evolution consist of size selections using a cell sorter and subsequent growth selections in cell culture. The size selections were defined as the smallest 1% of the population (Svr-lineage, (A)) and that around peak (Mld-lineage, (B)). As a control, the T-lineage consists of growth selection without size selection (C). The detailed procedure is described in the main text.