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Issue 239: In our recent paper, we study how resistant mutants carrying a fitness deficit can be rescued from purifying selection by continued evolution. The image shows a colony comprised of genetically tailored yeast cells allowing us to track the evolutionary trajectory of fluorescently labeled resistant mutants (red) with high spatial and temporal resolution. The opposing forces of radial population expansion and natural selection result in the formation of narrow but stable red streaks, formed by slower-growing resistant cells. This inflation-selection balance, a phenomenon first described in our work, inherently promotes the evolutionary rescue of resistant mutants by subsequent compensatory mutations (blue). As a result, the risk of therapy failure - made visible by the presence of resurgent growth domes at the periphery of the depicted colony - is dramatically increased. To learn more, click here.