Fig. 5: Including inflation-selection balance in a random walk model of range expansion reproduces experimental observations.

a Schematic of radial-random-walk model, simulating clone boundaries as a selection-biased 1D random walk along a radially expanding periphery. Inset: Selection can either reflect the full fitness cost (null model, see Fig. 2b, f), be reduced by a constant factor (f) or change as a function of clone width (b–g). b Simulated trajectories (same radius range as in experiments). Line width is proportional to the clone width at the colony edge. Inset: Width-dependent effective selection coefficient (see main text). c Width of compensated (blue) and uncompensated (red) clones. Solid lines represent the median width and shaded areas indicate interquartile ranges. Dashed lines represent mean values. d, e Estimated probability densities for the width of uncompensated (red) or compensated (blue) clones (see “Methods” for details). Hue indicates increasing colony radius over time. f Clone survival probabilities at the front (Eq. (1)) for different simulation scenarios (see legend). Note that with-rescue and no-rescue data overlaps for the neutral scenario. Shaded area indicates Poisson distribution SD. Experimental data is identical to that shown in Fig. 2f. g Efficacy of compensatory mutations (Eq. (2)) for the same scenarios shown in panel f) with matching line styles. Shaded areas indicate propagated SDs. Gray box represents the window of inefficacy for the width-dependent selection scenario. Experimental data (red) is identical to that shown in Fig. 2g. Source data are provided as a Source data file, if applicable (see ”Data availability” statement).