Scientists: New phylum sheds light on ancestor of animals, humans
November 2, 2006Genetic analysis of an obscure, worm-like creature retrieved from the depths of the North Atlantic has led to the discovery of a new phylum, a rare event in an era when most organisms have already been grouped into major evolutionary categories.
The analysis also appears to shed light on the ancestor of chordates, the backboned animals that include human beings and two small invertebrate groups closely related to one another: lancelets and tunicates.
“It’s a tremendous surprise that this mysterious creature from the ocean will help us understand our distant past,” said Leonid Moroz, a professor of neuroscience and zoology at UF’s Whitney Laboratory for Marine Bioscience near St. Augustine and one of the researchers who participated in the discovery.
Moroz and 13 other scientists report their findings today in the journal Nature.
Scientists have long been puzzled by the half-inch-long creature known by its scientific name of Xenoturbella and first retrieved from the Baltic Sea more than 50 years ago. Early genetic research identified it as a type of mollusk. But then scientists discovered the mollusk-like DNA actually resulted not from the creature itself, but from its close association to clams and likely habit of eating mollusk eggs, Moroz said. The Xenoturbella does not seem to have a brain, gut or gonads, making it unique among living animals.
More precise genomic sequencing at the Whitney Lab – where Moroz and his collaborators identified about 1,300 genes including mitochondrial genes – helped to reveal a surprise: Xenoturbella belongs to its own phylum, a broad class of organisms lying just below kingdom in taxonomic classification. It is one of only about 32 such phyla in the animal kingdom. “During the last 50 to 60 years, only a few new phyla have been established,” Moroz said.
Perhaps more significant, the analysis of Xenoturbella seems to confirm that human beings and other chordates share a common ancestor, a first in science. Its extreme characteristics suggest that this common ancestor – one the creature shares with its sister phyla, echinoderms and hemichordates, as well as chordates — did not have a brain or central nervous system.
“It is a basal organism, which by chance preserved the basal characteristics present in our common ancestor,” Moroz said. “This shows that our common ancestor doesn’t have a brain but rather a diffuse neural system in the animal’s surface.”
A reconstructed genetic record reported in the Nature article also implies that the brain might have been independently evolved more than twice in different animal lineages, Moroz said. This conclusion sharply contrasts the widely accepted view that the centralized brain has a single origin, Moroz noted.
Moroz added that the project is an example of interdisciplinary research involving scientists from three different countries, one that also integrates classical marine biology with modern genomic techniques. Scientists who participated in the research hailed from the University College of London, the Wellcome Trust Center for Human Genetics, the University of Chicago, Harvard Medical School, the University of California-Berkeley, the Broad Institute of MIT and Harvard, the Royal Swedish Academy of Sciences and the Whitney Lab.
Source: University of Florida
-
How many genes does it take to learn? Lessons from sea slugs
Dec 28, 2006 |
4.4 / 5 (16) |
0
-
Sea smarts: Scientists studying mollusks discover there is more than one way to make a brain
Sep 15, 2011 |
4.4 / 5 (9) |
4
-
Revisited human-worm relationships shed light on brain evolution
Feb 09, 2011 |
4.9 / 5 (8) |
1
-
Engineers build first sub-10-nm carbon nanotube transistor
Feb 01, 2012 |
4.9 / 5 (31) |
30
-
Something old, something new: Evolution and the structural divergence of duplicate genes
Jan 31, 2012 |
4.6 / 5 (7) |
1
-
The hidden nanoworld of ice crystals: Revealing the dynamic behavior of quasi-liquid layers
Jan 30, 2012 |
5 / 5 (3) |
1
-
Stock market network reveals investor clustering
Jan 27, 2012 |
3.9 / 5 (23) |
8
-
Of microchemistry and molecules: Electronic microfluidic device synthesizes biocompatible probes
Jan 26, 2012 |
5 / 5 (1) |
0
More news stories
Entire genome of extinct human decoded from fossil
(PhysOrg.com) -- In 2010, Svante Pääbo and his colleagues presented a draft version of the genome from a small fragment of a human finger bone discovered in Denisova Cave in southern Siberia. The ...
Feb 07, 2012 |
4.7 / 5 (57) |
43
|
Why are there so few fish in the Earth's oceans?
(PhysOrg.com) -- A Stony Brook University researcher has found that, contrary to popular belief, there are not plenty of fish in the sea.
Feb 08, 2012 |
4.3 / 5 (15) |
25
|
The power of estrogen -- male snakes attract other males
A new study has shown that boosting the estrogen levels of male garter snakes causes them to secrete the same pheromones that females use to attract suitors, and turned the males into just about the sexiest ...
Feb 10, 2012 |
4.8 / 5 (6) |
2
|
Miami battling invasion of giant African snails
No one knows how they got there. But an invasion of African giant snails has southern Florida in a panic over potential crop damage, disease and general yuckiness surrounding the slimy gastropods.
Feb 10, 2012 |
4.5 / 5 (2) |
5
Deciding to go left or right: Researchers use device to determine that lower animals can navigate too
For decades, scientists have associated binary decision making opting to go left or right with higher-ranking animals, including humans. A team of Harvard researchers, however, is rewriting that ...
Feb 09, 2012 |
4 / 5 (1) |
4
|
Walney offshore wind farm is world's biggest (for now)
(PhysOrg.com) -- The Walney wind farm on the Irish Sea--characterized by high tides, waves and windy weather--officially opened this week. The farm is treated in the press as a very big deal as the Walney ...
GPS court ruling leaves US phone tracking unclear
A US Supreme Court decision requiring a warrant to place a GPS device on the car of a criminal suspect leaves unresolved the bigger issue of police tracking using mobile phones, legal experts say.
Study finds that anti-diabetic medication can prevent the long-term effects of maternal obesity
In a study to be presented today at the Society for Maternal-Fetal Medicine's annual meeting, The Pregnancy Meeting, in Dallas, Texas, researchers will report findings that show that short therapy with the anti-diabetic medication ...
Europe stakes billion-dollar bet on new rocket
A pencil-slim rocket is scheduled to lift into space from South America on Monday, carrying a billion-dollar bet that Europe can grab a juicy slice of the market to place satellites in low orbit.
Netflix settlement trims 14 pct off 4Q earnings
(AP) -- Netflix pressed the rewind button on its fourth-quarter earnings after settling allegations that the video subscription service violated a consumer-privacy law.
Europeans protest controversial Internet pact
Tens of thousands of people marched in protests in more than a dozen European cities Saturday against a controversial anti-online piracy pact that critics say could curtail Internet freedom.