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Fig. 3 | EvoDevo

Fig. 3

From: In silico evo-devo: reconstructing stages in the evolution of animal segmentation

Fig. 3

Transient posterior signal without CCS yields only simultaneous segmentation. a Space–time plots of successfully evolved individuals, who mainly differ in the timing and number of tissue-wide division bursts. The right-most case only occurred once. The colour coding in the top row indicates cell type (based on the levels of all proteins); the white dots in the bottom row indicate new (just-divided) cells (see also “Methods”). Inset The initial conditions of the morphogen dynamics used in these simulations. The head cells do not divide. The posterior-most cell has high morphogen concentration, which is inherited by its daughters. The morphogen gene can be regulated by the evolving network, just like any other gene, but is not regulated initially. b The development of evolved individuals is not robust. The histogram depicts the number of bands generated when the development of a single evolved individual is repeated 50 times (see “Methods”). Lighter bars indicate the number of too short segments. Examples of the resulting development shown above with space–time plots of the divisions, with as inset the expression pattern of the segmentation gene. c Division timing plays a role in determining segment position. Cells which by chance happened to divide a bit later (circled in orange) form a lineage with high expression of the segmentation gene. d Time plots that show the dynamics in a high-segmentation gene stripe (left) and a low stripe (right). Note the changes in concentration of the division gene due to divisions

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