How mapping a fish’s genome can teach us about human evolution
“Little skate” may sound humble enough, but this funny looking shark relative—with giant fins fused around its flat head—is aiming for the big time.
In the MBL Whitman Center lab, Tetsuya Nakamura and José Luis Gómez-Skarmeta are working on their goal to bring the little skate into the select group of animals—along with human, mouse and a a few others—whose full complement of DNA (genome) has been mapped and functionally characterized to a high degree.
The little skate’s genome map will be “a huge resource for understanding human evolution and our vertebrate ancestry,” Nakamura said. Sharks and skates are ancient creatures that sit near the very base of the vertebrate lineage on the evolutionary tree. They are much more similar to humans than are zebrafish, which, despite being a common model organism in biomedical research, sit on a more divergent branch of the tree of life.
“Having the skate genome will open a lot of new research questions in evolutionary and developmental (evo-devo) biology, and people will come to MBL to answer them,” Gómez-Skarmeta said.
The Marine Resources Center at the MBL is the one of the only places in the world that collects this species of skate and breeds them for study, primarily for evo-devo biologists. These scientists compare how embryonic development is genetically regulated across many animal species, looking for the emergence of novel features, such as fins evolving into animal limbs.
What makes this quest so challenging is the fact that “most animals are constructed with the same toolkit of genes,” Gómez-Skarmeta explained. Among vertebrates, for instance, only 2 to 3 percent of the genome is protein-coding genes, and those genes are essentially the same in fish, mouse and human. Somewhere in the rest of the animal’s genome, sometimes called the “dark matter,” are the instructions for how those genes will function, and these instructions will be very different across species.
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