Figure 2.

Emergence of innovative offspring can be constrained by parental phenotypes. (A) The horizontal axis shows the carbon source on which parental metabolisms are viable, and the vertical axis shows the number of novel carbon sources (among the remaining 49 carbon sources) on which at least one innovative offspring resulting from recombination between parental metabolic networks is viable. (B) Given here is the fraction of innovative recombinants (coded according to the color legend) resulting from recombination between parents viable exclusively on the carbon source specified on the vertical axis, which have gained viability on the novel carbon source specified on the horizontal axis. (C) Dendrogram of carbon sources clustered based on their innovation distance defined by the data in (B). We used the unweighted pair group method with arithmetic means for clustering carbon sources. Branches colored in red and cyan correspond to glycolytic and gluconeogenic carbon sources, respectively (except D-galacturonate, L-galactonate, and D-glucoronate (cyan circles), which are the gluconeogenic carbon sources). In these analyses, parental metabolic networks contain ||G|| = 2079 reactions, the same number as the E. coli metabolic network, and they differ in D = 100 reactions. Moreover, n = 10 reactions are swapped between parental metabolic networks during recombination.