Figure 5

A spatial schematic of genotype network connectivity at different metabolism sizes n . Each panel shows a funnel-like landscape, where the funnel’s width reflects the number of potential metabolisms that are viable at any given number n of reactions (altitude in the landscape). The lowest points of the landscape correspond to potential metabolisms whose size are close to the smallest possible n needed for viability. Solid and dotted lines denote random sequences of reaction removal from some viable starting metabolism (not shown) that terminate at a particular size n and result in some viable metabolism denoted by circles. Depressions in the funnel correspond to disconnected components of the genotype network. Disconnected components in (A) arise at higher metabolism sizes than in (B). Two of the trajectories in A (solid lines) terminate in such depressions, that is, in potential metabolisms that are part of a disconnected component. These metabolisms are not interconvertible through viability preserving reaction swaps. The same trajectories in B terminate at a part of the funnel where all viable metabolisms are still connected. The figure was generated using a script from (http://www.oaslab.com/Drawing_funnels.html)