Coping with uncertainty: Challenges for robust pattern formation in dynamical tissues.

An outstanding question in biology is how tissue patterning emerges during development. The concept of positional information, which posits that gradients of morphogens instruct cell fate in a concentration-dependent manner, has been an influential framework to understand pattern formation. Recent studies, however, highlight that developing tissues are highly dynamic, with cellular movements, arising from local mechanical fluctuations or global morphogenetic forces, that often coincide with morphogen signaling and cell fate specification. This calls for a more dynamic understanding of pattern formation by explicitly investigating the interplay between signaling, cell fate and morphogenesis. In this review, we first discuss emerging evidence on the role of cellular movements in modulating signaling dosage and cell fate acquisition. We then examine the biophysical strategies employed by developing tissues to achieve robust patterning despite ongoing cellular dynamics and large-scale morphogenesis. While cellular movements may intuitively be viewed as disruptive to patterning programs, recent evidence suggests that when coupled with cell fate, they can act as a critical mechanism for generating and stabilizing precise tissue patterns during development.