Cell shape anisotropy and motility constrain self-organised feather pattern fidelity in birds

Summary Cellular self-organisation can emerge from stochastic fluctuations in properties of a developing tissue 1–3 . This mechanism explains the production of various motifs seen in nature 4–7 . However, events channelling its outcomes such that patterns are produced with reproducible precision key to fitness remain unexplored. Here, we compared the dynamic emergence of feather primordia arrays in poultry, finch, emu, ostrich and penguin embryos and correlated inter-species differences in pattern fidelity to the amplitude of dermal cell anisotropy in the un-patterned tissue. Using live imaging and ex vivo perturbations in these species, we showed that cell anisotropy optimises cell motility for sharp and precisely located primordia formation, and thus, proper pattern geometry. These results evidence a mechanism through which collective cellular properties of a developmental pattern system ensure stability in its self-organisation and contribute to its evolution.