Alternate title: The Sound of the Tree of Life Exploding
Comparing the sequence to other species also turned up a big surprise. When the researchers compared the human ultraconserved element to all the DNA sequences in the public database GenBank, the closest match was to DNA from the coelacanth…
Okay, so maybe it didn’t explode but some branches are bent and something is definitely fishy here. Rubin, Haussler, and Bejerano sure do turn up some interesting things. Our closest relative on the tree of life according to ultra-conserved DNA is a fish that’s been around unchanged for at least 360 million years.
“The big question is whether this is a special case or whether it’s the tip of the iceberg,” says Haussler. A report on the research is published in the May 4, 2006, issue of the journal Nature.
Haussler and his colleagues were led to the discovery through their work on the ultraconserved elements of the genome. One ultraconserved element in particular caught their eye. “We were very interested in this sequence, because it had a number of copies elsewhere in the genome,” says postdoc Gill Bejerano, who is the first author of the study. Close copies of the sequence were ubiquitous in amphibians, birds, and mammals, indicating that it served an important function. “We found it in every species for which we have genomes, from frogs to humans,” says Bejerano.
Comparing the sequence to other species also turned up a big surprise. When the researchers compared the human ultraconserved element to all the DNA sequences in the public database GenBank, the closest match was to DNA from the coelacanth — an ancient fish thought to have gone extinct millions of years ago until a live specimen was caught in 1938 off the east coast of South Africa. The coelacanth is a descendant of the ancient marine organism that gave rise to the terrestrial vertebrates more than 360 million years ago. Humans are therefore separated from the coelacanth by hundreds of millions of years of evolution, yet the two organisms still share critical DNA sequences.
Read the whole article at the link above.