  How do the topology and geometry of a tubular network affect the spread of
particles within fluid flows? We investigate patterns of effective dispersion
in the hierarchical, biological transport network formed by Physarum
polycephalum. We demonstrate that a change in topology - pruning in the
foraging state - causes a large increase in effective dispersion throughout the
network. By comparison, changes in the hierarchy of tube radii result in
smaller and more localized differences. Pruned networks capitalize on Taylor
dispersion to increase the dispersion capability.
