Figure 4
From: Comparative genomics of Lbx loci reveals conservation of identical Lbx ohnologs in bony vertebrates
A model of the evolution of the vertebrate Lbx/Tlx loci. Lbx loci in extant vertebrates arose from a region containing an Lbx, Tlx, Fgf8/17/24/18 and an Npm gene. After one round of whole genome duplication (1R WGD) Lbx1/4 and Lbx2/3 precursors were produced linked to Fgf8/17 – Npm2/3 and Fgf24/18 – Npm4/1 precursors, respectively. During the second round of whole genome duplication (2R WGD), four loci where produced. By the time of the divergence of the lobed-fined and ray-finned fish, the Lbx4, Tlx4 and Lbx3 genes (shown in grey) had been lost.