Figure 2.

The fate of duplicated teleost GRBs. If the target gene (red) is retained in both copies, then the two loci/genomic regulatory blocks (GRBs) undergo degenerative changes. This occurs either through chromosomal breaks (left), removing the bystander gene, which may land elsewhere in the genome and which loses the highly conserved noncoding elements (HCNEs); or by loss, through neutral evolution, of the bystander gene and some HCNEs (which are both retained in the intact other copy of the GRB).