Real-life images for considered case studies. (A) Multiple bacterial colonies with phase variable genes. Sector-like patterns (highlighted in black) are an indication of high proportions of “mutant” cells (i.e. cells with switched gene expression). Conversely gray parts of the colony are an indication of high proportions of wild-type cells. (Reproduced with permission from . Copyright Ⓒ 1998, American Society for Microbiology). (B) Population of Dictyostelium discoideum cells chemotactically aggregating in the centre where the chemical attractant concentration is highest (Reproduced with permission from ).