Extended Data Figure 2: The reachability plot for Fig. 3a.

The distance between subsequent solutions as calculated by equation (1) in a list sorted according to the pairwise distance between solutions. The index is the position of the solutions in the list. Valleys identify closely spaced solutions, denoted clans. The valleys corresponding to tunnelling and shovelling clans are marked with yellow and blue respectively. The black line marks the threshold for the distance between consecutive solutions in a clan at 0.05.