Reef Relations
DNA shared by people and coral sheds light on animal evolution
By John Travis
The reef-building coral Acropora millepora does not have a lot on its mind. In fact, it doesn’t have a mind at all. The invertebrate has only a diffuse net of nerve cells, one of the simplest nervous systems of any animal. Thus, it shocked Australian geneticist David Miller to find that the coral’s DNA contains genetic sequences corresponding to genes that guide the patterning of the incredibly complex human nervous system. Worms and flies don’t have these genes, so he and other researchers had taken it for granted that the genes were relatively recent innovations that had evolved in vertebrates.
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The nervous system genes are among a surprisingly large number of genes shared by vertebrates and A. millepora, but not by the worm Caenorhabditis elegans or the fruit fly Drosophila melanogaster, Miller and his colleagues have found. This discovery demands rethinking of the common ancestor of corals and all other animals, the researchers say in the Dec. 16, 2003 Current Biology.