Non-clonality of cell types contributes to the robustness of the <i>C. elegans</i> lineage.

<p>(A–B) Lineage robustness in the presence of (A) necrosis or (B) program failure declines with the rise of clonality in 1050 random lineages with different levels of clonality. These lineages are generated by different degrees of clustering of terminal cells of the same types while constraining the lineal topology and depths of all terminal cells as in <i>C. elegans</i>. The different degrees of clustering are shown by different colors, with the scale shown at the top left corner of the figure. The dashed line is the linear least-square regression. The rank correlation between clonality and robustness, as well as the associated <i>P</i>-value, are presented. The <i>C. elegans</i> lineage is indicated by a triangle. (C) Spatial requirements cannot explain the low clonality of the real lineage. The 1050 random lineages with different levels of clonality are plotted, showing that the increase of clonality promotes the rank correlation (ρ_p-l) between <i>p</i>hysical and <i>l</i>ineal distances of terminal cells of the same type. The triangle indicates the real lineage, while the square indicates an artificial lineage with the same topology, depths of all cells, and clonality as the real lineage, but a higher ρ_p-l. The <i>C</i> values here are different from those appearing in panels A, B and F, because not all <i>C. elegans</i> terminal cells have three-dimensional coordinates. (D–E) Spatial constraint lowers lineage robustness in the presence of (D) necrosis or (E) program failure. Red dots are random lineages generated by random rearrangement of terminal cells within their respective depths, whereas blue dots are generated with the additional constraint that twin terminal cells, which share their immediate progenitor and their cell type, are maintained. <i>P</i>₁ is the probability that the clonality is equal between the blue and red dots (Mann-Whitney <i>U</i> test), whereas <i>P</i>₂ is the probability that the robustness is equal between the blue and red dots (Mann-Whitney <i>U</i> test). All <i>P</i> values are calculated based on 10,000 red and 10,000 blue dots. For clarity, only 100 red and 100 blue dots are shown here. (F) Lineage complexity decreases with the rise of clonality among the 1050 random lineages. The rank correlation between clonality and complexity, as well as the associated <i>P</i>-value, are presented. The <i>C. elegans</i> lineage is indicated by a triangle.