Fig. 1.

Two principles for inferring developmental hierarchy from lineage tracing barcodes. (A) Barcodes are deposited over time. Multiple insertions in the same lineage of cells create a nested hierarchy of barcoded clones that encode the lineage hierarchy. For example, the blue barcode that is in cell types A and B, but not C, suggests a common progenitor for A and B. (B) Barcodes are deposited all at once. Lineage hierarchy can no longer be inferred from the nesting of barcoded clones but may be encoded in the shared fluctuations of barcode abundance in terminal states. For example, an initial imbalance in the abundance of cells with the red versus blue barcode in the progenitors of A, B, and C manifests eventually in the shared enrichment of red-barcoded cells in A and B.