Fig. 1

Historical contingency and adaptation in theoretical fitness landscapes. a and b Adaptive trajectories of a single ancestor (grey dots) in two environments represented by two-dimensional fitness landscapes. Light blue (a) and light red (b) dots indicate the position of a theoretical population after adaptation. c and d when the two populations resulting from the initial adaptation events are placed in the same environment (light blue and light red dots), historical contingency may cause adaptive convergence (c) or divergence (d) depending on both the past environment and the fitness landscape of the new environment. Dark blue and dark red dots indicate the position of the populations after adaptation to the new environment. White arrows indicate adaptive trajectories. In the landscapes, fitness increases from white to black