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. 2016 Dec 15;12(12):892. doi: 10.15252/msb.20166951

Figure 3. Ultrafast arsenic adaptation is explained by plain neo‐Darwinian mechanisms.

Figure 3

  • A, B
    Simulating populations (n = 500) with different mutation parameters adapting to arsenic, in an individual cell‐based model. Each cell has a cell division time (population doubling time) and a time to the first cell division (lag). Cell division times were recorded every 5th cell division, and population means were expressed as the fraction of founder growth w/o arsenic recovered. (A) Mutations affect only cell division time. Grey lines = 500 adapting populations. Black lines = quantiles corresponding to the fastest 1, 10, 25, 75, 90 and 99% of populations. Red line = median population. Blue line = empirical arsenic populations, P1–P4. (B) Contrasting simulations with mutations only affecting cell division time (model 1, M1, y‐axis) or both cell division time and the time to the first cell division with the same effect size and direction (model 2, M2, x‐axis). The number of cell divisions required to recover 25% (left panel), 50% (middle panel) and 75% (right panel) of founder growth w/o arsenic is shown. The 227 fastest scenarios, with 75% recovery in ≤ 100 cell divisions, are displayed. Dot size = number of populations. Black dot = median population.
  • C
    Simulated competition in arsenic between WT and ACR3 (top panel), ASK10 (middle panel), and FPS1 (lower panel) mutation‐carrying cells, respectively. Mutations emerge in a single cell at t = 0 in WT population and have empirical effects on doubling time and/or growth lag. Coloured lines = model with individual cells and genetic drift. Black lines = deterministic model based on subpopulations of cells.
  • D
    Arsenic adaptation of 25 simulated populations in an individual cell‐based model, given basal, 3×, 5× and 10× mutation rates. Beneficial mutations in FPS1 (green), ASK10 (red) and ACR3 (blue) occur randomly at estimated frequencies and have empirical lag and doubling time effects. Left hand side: Before t = 250 generations. Horizontal bars = mutated alleles exist at (sum) P > 50%. Vertical black lines = WT allele goes extinct. Right hand side: At t = 250 generations. Dot presence = WT allele extinct. Dot colour = gene name. Dot size = number of mutated alleles at P > 5%.