Extended Data Fig. 2: Progression of GBE is comparable in all species, while only D. melanogaster and M. abdita form the CF.

Figure shows montages of representative time lapse recordings of developing embryos from our species of interest. T₀ is defined as the initiation of gastrulation. Asterisks mark/track the CF in D. melanogaster and M. abdita. In all species, the white arrows track the posterior end of the ectoderm at the indicated %EL on the left. In Empis sp. and H. illucens GBE never reaches 60% EL; the gray arrows thus indicate the end point of GBE at ~55% EL. n = 35, 24, 3, 21, 6, 27, and 42 embryos respectively for D. melanogaster, M. abdita, Empis sp., H. illucens, C. fuscipes, C. riparius, and C. albipunctata. Of note, these numbers only include embryos with sagittal sections, as shown. We have also confirmed the presence (in Cyclorrhapha) and absence (in non-Cyclorrhapha) of CF throughout gastrulation, in embryos imaged in coronal views, since we can easily determine the initiation and end of GBE in these views. We do not present data with coronal views, however, as it is not possible to unequivocally determine the extent of GBE at a given time point, which is possible only in a sagittal view. Scale bars, 50 µm.