Morphogenesis of termite mounds

Several species of termites across Africa, Asia, Australia, and South America collectively construct meter-sized porous mound structures that regulate mound temperature, humidity, and gas concentrations. These mounds display varied yet distinctive morphologies that range widely in size and shape. To explain this morphological diversity, we introduce a mathematical model that couples environmental physics to insect behavior: the advection and diffusion of heat and pheromones through a porous medium are modified by the mound geometry and in turn modify that geometry through a minimal characterization of termite behavior. Our model captures the range of naturally observed mound shapes in terms of a minimal parameter set and suggests several simple scaling laws for mound morphology and construction time. An elaboration of our model that incorporates 3D internal nest structure gives rise to regularly spaced floors and pillars, as well as the spontaneous generation of helical ramps, as have been observed in scanned mounds across termite species. This framework makes testable hypotheses for the response of mound morphology to external temperature oscillations and internal odors.