Figure 7: Composition of the ancestral osteichthyan genome.

The 110 DCS blocks identified on the human genome are grouped according to their composition in terms of Tetraodon chromosomes, thus delineating 12 ancestral chromosomes containing 90 DCS blocks. The order of DCSs within an ancestral chromosome is arbitrary. The 20 blocks denoted by the letters U, V, W and Z (Supplementary Information) could not be assigned to an ancestral chromosome because each has a unique composition, probably due to rearrangements in the human or Tetraodon genome. Colour codes are as in Fig. 6.