Clonal dominance in excitable cell networks

Clonal dominance arises when the descendants (clones) of one or a few founder cells contribute disproportionally to the final structure during collective growth^1–8. In contexts such as bacterial growth, tumorigenesis and stem cell reprogramming^2–4, this phenomenon is often attributed to pre-existing propensities for dominance, whereas in stem cell homeostasis, neutral drift dynamics are invoked^5,6. The mechanistic origin of clonal dominance during development, where it is increasingly documented^1,6–8, is less understood. Here, we investigate this phenomenon in the Drosophila melanogaster follicle epithelium, a system in which the joint growth dynamics of cell lineage trees can be reconstructed. We demonstrate that clonal dominance can emerge spontaneously, in the absence of pre-existing biases, as a collective property of evolving excitable networks through coupling of divisions among connected cells. Similar mechanisms have been identified in forest fires and evolving opinion networks^9–11; we show that the spatial coupling of excitable units explains a critical feature of the development of the organism, with implications for tissue organization and dynamics^1,12,13.