Of Mice, Men, and Coelacanths
| December 11, 2006 | Posted by Dave S. under Intelligent Design |
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 coelacanthâ€â€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.
70 Responses to Of Mice, Men, and Coelacanths
Leave a Reply
You must be logged in to post a comment.
Jehu, if I am understanding your quote correctly, this scientist is saying that the 4 HDAC gene does not by any means express itself as a phylogenic tree like the majority of other genes do, is that correct? In fact, he seems to be suggesting that if one used the HDAC gene as the source gene to determine the phylogenic tree, the tree would cross the philum barrier all over the place. Is that basically the bottom line?
If so, these guys have a lot of work to do figuring out how all of this HGT is happening. At the moment, my bet is with little green men with microscopes and very sharp needles.
When is this theory going to shatter? How loud will the explosion be?
bFast,
bFast, I don’t know if a majority of the other genes line up as a phylogenic tree. In fact I doubt any of them line up 100%. If you recall the article Patrick posted, different genes give you different trees.
Here’s another good one.
“Humpback whales have brain cells also found in humans”
Horizontal gene transfer?
http://www.eurekalert.org/pub_.....112006.php
Jehu, this one looks like convergence to me. I don’t think that NDE explains the level of convergence that is, but the same mechanism that caused the greater and lesser pandas to have matching thumbs, did this.
bFast, I am not sure how you can tell the difference between convergence and horizontal gene transfer. To me it looks like common design.
BTW, the prediction I made in post #53 has already come true – again.
See this article in the New York Times:
http://www.nytimes.com/2006/12.....tner=MYWAY
Pretty soon we might actually have rabbits in the cambrian
Don’t be silly. If a rock has a rabbit fossil in it then it is obviously not cambrian rock.
[/sarcasm]
And it wouldn’t be a rabbit anyway, it would be an interesting example of convergent evolution.
jehu, “bFast, I am not sure how you can tell the difference between convergence and horizontal gene transfer. To me it looks like common design.”
As genes are proported to undergo convergence, I am sure that sometimes the analysis of genes would create a situation where the evolutionary scientist would have a tough time telling the difference between the two.
However, your example is of cells, not genes. In this case, I think it pretty clear that we are encountering convergence. I do, by the way, consider the rediculous extent of convergence to be excellent evidence in favor of intelligent design. I do not believe that MET can do a reasonable job of explaining it.
The original article in Nature completely refutes your argument. It states in the abstract:
“One of these, a more than 200-base-pair ultraconserved region, 100% identical in mammals, and 80% identical to the coelacanth SINE …”
Nowhere in the Nature article do the authors claim that ultra-conserved DNA in the coelacanth is closer to Humans than is any other animal.
fallible
The Nature article actually does confirm this but the HHMC quote might be misleading in that the ultraconserved element isn’t the closest match. The ultraconserved element is a retrotransposon. It is ultraconserved amongst mammals and is also present (highly but not ultraconserved) in coelacanths. The retrotransposon in question inserts copies of itself into the genome of its host. There are many copies of it in all the organisms mentioned. Insertions of it that appear in the human genome are closer in sequence to some insertions in the coelacanth than they are even to other insertions in the human genome. Thus if you are comparing a copy of this retrotransposon in humans to copies in other organisms you get a closest match in the coelacanth. The only misleading part of the HHMC quote is that the copies are ultraconserved between human and coelacanth.
Thanks for your interest but in regard to me making any correction in the blog post – there is nothing to correct. Anything misleading in regard to HHMC’s use of “ultraconserved” has been addressed in the commentary.