Figure 5
Summary of the Tbx4 C-LME in osteichthyan evolution.
Possession of the Tbx4 core lung mesenchyme-specific enhancer (C-LME) is summarized on a simplified phylogenetic tree of osteichthyes. The blue line shows the possession of Tbx4 C-LME in sarcopterygians and actinopterygians, corresponding to the possession of lungs. Lungfish are assumed to possess the Tbx4 C-LME due to the existence in coelacanths. The blue squares indicate presumptive positions for functional loss of the Tbx4 C-LME during the evolution of actinopterygians. We indicate the point at which this loss may have occurred. The red arrow indicates the timing of 3R-WGD (teleost specific whole-genome duplication).
