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

Figure 1. Arsenic adaptation is ultrafast and heritable.

Figure 1

  1. Schematic illustration of the extraction of the fitness components: length of lag phase (h), growth rate (doubling time, h) and growth efficiency (total change in population size, OD). Absolute fitness components were log(2)‐transformed. When comparisons across experimental plates were performed, absolute log(2) values were first normalized to the corresponding mean value of many founder populations in randomized positions on the same plate, producing relative fitness components (see Materials and Methods). A positive relative performance equals good growth.
  2. Fitness components of As(III) adapting populations (n = 2) relative the founder (n = 4). Blue = 5 mM As(III). Red = no As(III). Colour = populations P1–P4.
  3. Mean adaptation speed under 18 selection pressures (n = 4 independent populations) for doubling time. A monotone function was fitted to each adaptation curve using least squares and the function isoreg in R (version 2.15.3). Two measures of adaptive speed were extracted from the function: (x‐axis) the number of generations required to reach 25, 50 and 75% of the final doubling time (t = 250 generations) and (y‐axis) the fraction (%) of the initial gap to the founder doubling time in optimal environments (no stress added) that was recovered at these time points. Colour indicates challenge.
  4. Absolute log(2) fitness components of arsenic‐adapted (t = 250 generations) populations in 5 mM As(III), before (blue bars) and after (red bars) a 75 generations release from selection. Green bars: founder in 5 mM As(III). Yellow bars: founder without arsenic. Error bars represent SEM (n = 2).

Source data are available online for this figure.