Bifurcation in cellular evolution
Aspects of cell metabolism are modeled by ordinary differential equations describing the change of intracellular chemical concentrations. There is a correspondence between this dynamical system and a complex network. As in the classic Erdős--Rényi model, the reaction network can evolve by the iterative addition of edges to the underlying graph. In the biochemical context, each added reaction implies a metabolic mutation. In this work it is shown that modifications to the graph topology by gradually adding mutations lead here too to the formation of a giant connected component, i.e., to a percolation--like phase transition. It triggers an abrupt change in the functionality of the corresponding network. This percolation is mapped into a bifurcation in the intracellular dynamics. It acts as a shortcut in biological evolution, so that the most probable metabolic state for the cell is suddenly switched from cellular stagnation to exponential growth.