Figure 6.

A hypothesized scenario for dlx gene evolution. Evolution of gene repertoires, gene cluster structure and conserved non-coding elements (CNEs) are shown (see Materials and Methods, for our criteria in assigning CNEs). Timing of gains and losses of CNEs is based on the most parsimonious interpretation. Dlx7 and Dlx8 are hypothetical genes that are thought to have existed immediately after two rounds of whole genome duplication. Alphabets in the names of CNEs: I = intergenic CNE; F = flanking CNE; M = mammal specific CNE; P = pufferfish specific CNE; A = amniote specific CNE; T = tetrapod specific CNE; 1R/2R = two rounds of whole genome duplications; TSGD (3R) = teleost-specific genome duplication.