Genome of unique fish species may give clues to vertebrate evolution

The genome of the African coelacanth, a creature whose evolutionary history is enigmatic, sheds light on the evolution of land vertebrates, researchers say. The genome of the coelacanth, a fish once believed extinct until live examples began to be caught in the 20th century, is providing a wealth of information on the genetic changes that accompanied the adaptation from an aquatic environment to land, scientists said. Because of their resemblance to fossils dating back millions of years, coelacanths are sometimes dubbed "living fossils," a tag researchers say is inappropriate. "It's not a living fossil; it's a living organism," research scientist Jessica Alfoldi of the Broad Institute in Cambridge, Mass., said. "It doesn't live in a time bubble; it lives in our world, which is why it's so fascinating to find out that its genes are evolving more slowly than ours." Coelacanths possess some features that look oddly similar to those seen only in animals that dwell on land, including "lobed" fins, which resemble the limbs of four-legged land animals known as tetrapods. The coelacanth genome can serve as a blueprint for better understanding tetrapod evolution, the researchers said. "This is just the beginning of many analyses on what the coelacanth can teach us about the emergence of land vertebrates, including humans, and, combined with modern empirical approaches, can lend insights into the mechanisms that have contributed to major evolutionary innovations," study co-author Chris Amemiya, a biologists at the University of Washington, said.