Abstract
The slime mold Physarum polycephalum is a unicellular but multi-nucleated organism, which amazingly can grow up to square meters. It forms extended vein networks in order to search for food. The structure and dynamics of the foraging units is dependent on environmental conditions and life stage. We find oscillating microplasmodia, which percolate into a network directly or fuse into compact satellites before transforming into networks as well. We model the percolations transition, which occurs in well-fed conditions, analytically within the configuration model of graph theory utilizing all partaking types of nodes. Quite generally, we find that at the percolation transition the formation of a small link degree network is topologically highly constrained and only weakly dependent on environmental factors. Structuring of the network as characterized by global efficiency and centrality measures precedes area search in order to forage. In contrast, satellites are found to be predominant after prolonged starvation of microplasmodia. The number and size of satellites forming out of a spherical patch of single microplasmodia shows characteristic scaling behavior with coverage. After radially swarming away from the patch, satellites develop holes and transform into networks. We have obtained flow patterns within external (network) and internal (satellite) veins and gained ultra-structural insights into their morphology and topology.
To learn more about this speaker, please visit his research webpage.