Clonal selection upon serial transplantation (Tx). (A) Barcode composition in serial xenografts of donor ALL-70. Each circle represents 1 mouse. Primary xenografts are depicted in the center gray circle; arrows connect each donor to its serial recipients. The background colors mark descendants of the same ancestor. (B) Quantification of barcode complexity in blood of serial xenografts of donor ALL-70. Each dot represents 1 mouse at a certain time point. Dashed lines connect the donor to its serial recipients. (C) Barcode complexity in spine bone marrow of serial recipients. Each dot represents 1 mouse. Detailed information on bone marrow composition of all recipients of ALL-58 can be found in supplemental File 11. (D) Degree of determinism in barcode composition between recipients of the same donor is expressed by Spearman rank coefficient. For example, for donor ALL-70, we calculated Spearman rank coefficients for barcode composition in spine bone marrow among the 3 primary recipients (A, gray circle), between the secondary recipients, and between their tertiary recipients. Only mice receiving the same cell dose (red and yellow area) are plotted.