Fig. 5.

Evolution of Pax genes deployed for animal eye development. 1: Gene duplications that gave rise to distinct Pax classes (corresponding to subfamilies) occurred. 2: The ancestral animal eye evolved and different classes of Pax genes were redundantly recruited for eye development. 3: In each of three different animal lineages, a specific Pax gene was selected for the eye development. 4: Pax genes responsible for eye development were altered in some bilaterians. See text for detailed description.