Fig. 9.

Independent expansions of the fetua gene complex occurred in three snake families. The organization of the fetua locus in fish, mammals, birds, and reptiles. Genes (colored arrows) within the same gene family have the same color (fetua—blue, fetub—orange, senp5—gray, and hrg—green). The fetua gene complex is flanked by fetub to the right and senp5 to the left in all animals examined except for mammals and shark. Three independent expansions of the fetua locus occurred in snakes (indicated by yellow circles) and yielded multiple fetua genes in colubrids, elapids, and vipers. Elephant shark (Callorhinchus milii), mouse (Mus musculus), chicken (Gallus gallus), box turtle (Terrapene triunguis), green anole (Anolis carolinensis), boa (Boa constrictor), python (Python bivittatus), garter snake (Thamnophis elegans), cobra (Naja naja), common European adder (Vipera berus), hundred pacer (Deinagkistrodon acutus), Habu (Protobothrops flavoviridis), and western diamondback rattlesnake (Crotalus atrox).