Fish Lost in Deep Time — The Evolutionary Origins and Mechanisms of the Tetrapod Bodyplan
Tetsuya Nakamura
Rutgers the State University of New Jersey
Finding the evolutionary origins of our body plan is a fundamental challenge in biology. Tetrapods acquired myriad evolutionary innovations, including the neck and limb, during the transition from aquatic to terrestrial habitats. Despite the functional importance of these novel structures, the extinction of transitional animals along the water-to-land axis has hindered our understanding of their evolutionary antecedents and trajectories. Over the last several years, by bridging functional genomics, genetics, and embryology, our group has explored the ontogenetic and evolutionary origins of terrestrial limbs and shoulders within the ray-finned fish body plan. We uncovered several critical genetic mechanisms underlying the development of functional appendages that meticulously coordinate skeletal, muscular, and neural development. Unexpectedly, we not only identified the genetic basis of functional limb development, but also discovered a latent ability in fish to generate the pectoral morphology akin to tetrapod digit bones, shoulder girdle, and neck. In this seminar, I introduce recent discoveries that reveal the deep conservation of tetrapod locomotory organs through the long evolutionary journey of tetrapod ancestors and the mechanisms underlying their transformation.