Colonies of reproducing microorganisms can invade their environment through the combined effect of proliferation and diffusion. When the diffusivity of the microorganisms is constant, colony fronts have been classified either as pulled, when their propagation is determined by the dynamics at the foot of the front, or pushed, when propagation depends on the whole front profile. If the cell diffusivity is not a constant but depends on the local population density, richer dynamics are observed. Density patterns can emerge in the colony bulk that also propagate and interact with the leading edge. In this talk, I will discuss this interplay and I will show in particular how the pattern front velocity is locked to the leading front velocity, which can result in an acceleration of the pattern formation. In turn, in some extreme cases, motility-induced pattern formation in the bulk can have dramatic consequences on the colony by triggering its premature extinction.
Accès Salle des séminaires FAST-LPTMS (Bât. 530, salle C.120, 1er)