Evolution during an AND-to-OR environmental transition. Snapshots of the minimal network evolution for a single cell during an AND-to-OR transition are shown. T0 is the metabolic triplet, and RP0 is the response protein, whose expression is necessary for nutrient uptake (its expression profile is the third row in the heatmap). (A) Initially the cell is exposed to the AND environment, and exhibits a highly fit profile (Pearson correlation between RP0 and nutrients is 0.89). The minimal network illustrates the logic that has evolved: signal S1 activates the expression of gene and protein product of T1, which in turn catalyzes the translation of T0, while signal S1 should be presence for T0 gene expression, thus operating in an AND-like logic. (B) Upon exposure to the OR environment, the cellular network evolves to exhibit suboptimal phenotype, where only the second and third nutrient peaks are detected. (C) Final OR-like network evolves after several epochs from the intermediate network (shown in B). The cell expresses its metabolic protein during all nutrient occurrences.