Extended Data Fig. 6: Transcriptomic dynamics of anteroposterior genes.

a, Schematic drawing of the adult body regions used to define anterior and posterior and trunk genes. b, Correlation matrix of RNA-seq experiments from all nine adult tissues, calculated from a variance stabilising-transformed matrix of the normalised DESeq2 matrix. c, Venn diagram showing the number of tissue-specific and shared expressed genes (TPM > 2). Gene sets highlighted with red text were defined as adult anterior, and adult posterior and trunk genes. d, Phylostratigraphic classification of adult anterior, and adult posterior and trunk genes, compared to the whole genome and a random subset of 1,000 genes. e,f, Expression dynamics of each phylostratum by developmental stage in the adult anterior (e), and adult posterior and trunk gene sets (f), calculated from the 75 % percentile of a quantile-normalised matrix of gene expression levels. Adult anterior genes of most phylostrata peak at the blastula, while the maximum expression of adult trunk/posterior genes of most phylostrata peak at post-larval stages. g–l, Average expression dynamics of in situ hybridisation-validated anterior, trunk, and posterior markers throughout O. fusiformis (g,h), C. teleta (i,j), and D. gyrociliatus (k,l) development. For boxplots in g,i, and k, centre lines, median; box, interquartile range (IQR); whiskers, first or third quartile ± 1.5 × IQR. Lower whiskers are sometimes not apparent due to the distribution skewness towards zero. Curves in h,j, and l are locally estimated scatterplot smoothings. Coloured shaded areas represent standard error of the mean. n = 23, 8, and 17 anterior markers, 10 and 3 posterior markers, and 15, 10, and 8 trunk markers, for O. fusiformis, C. teleta, and D. gyrociliatus, respectively. Key stages where expression of trunk markers is incipient are shown for both O. fusiformis and C. teleta.