Genealogy of scaly reptiles rewritten by new research

EurekAlert (AAAS) ^ | 22 November 2005 | Barbara K. Kennedy

[PatrickHenry]

The most comprehensive analysis ever performed of the genetic relationships among all the major groups of snakes, lizards, and other scaly reptiles has resulted in a radical reorganization of the family tree of these animals, requiring new names for many of the tree's new branches. The research, reported in the current issue of the journal C. R. Biologies, was performed by two biologists working at Penn State University: S. Blair Hedges, professor of biology, and Nicolas Vidal, a postdoctoral fellow in Hedges' research group at the time of the research who now is a curator at the National Museum in Paris.

Vidal and Hedges collected and analyzed the largest genetic data set ever assembled for the scaly reptiles known as squamates. The resulting family tree has revealed a number of surprising relationships. For example, "The overwhelming molecular-genetic evidence shows that the primitive-looking iguanian lizards are close relatives of two of the most advanced lineages, the snakes on the one hand and the monitor lizards and their relatives on the other," Vidal says.

Looks can be deceiving. New gene study redraws family tree of lizards and puts primitive-looking iguanas (shown here) and relatives at the top instead of bottom of the tree.
[Photo credits in original article]

"We gave this group the new name, 'Toxicofera' because of another discovery, reported in a related paper, that some lizard species thought to be harmless actually produce toxic venom, as do some snakes--including some large monitor lizards in the same family as the giant Komodo Dragon and some large species of iguanians." Vidal, Hedges, and other researchers report this and other discoveries about the early evolution of the venom system in lizards and snakes in a paper led by Bryan G. Fry, of the University of Melbourne in Australia, published in the current issue of the journal Nature. "It's a really startling thing that so many supposedly harmless lizards actually are venomous," Vidal comments, "but their sharing of this characteristic makes sense now that our genetic studies have shown how closely they are related."

The diversification of such a large group of animals, including 8,000 living species, into many ecological niches is a major pattern of biological evolution on Earth. "We used to think that venom evolved relatively recently, but this study shows that it evolved very early in the history of these species, about 200-million years ago, when dinosaurs were just getting started," Hedges explains. "We would like to understand what factors had major effects on biological evolution at that time in the Earth's history and why these species survived but the dinosaurs did not." This research also could help scientists find fossils of more species because it reveals new information about the age of the geological formations in which the fossils can be found. In a broader context, this work is part of astrobiology research, which seeks to understand general mechanisms of evolution that might apply to other worlds.

To increase the statistical confidence of their results, Vidal and Hedges included twice the amount of genetic information as was used in previous studies of these species. The team's data include nine nuclear-protein-coding genes from 19 species representing all major lineages -- mostly families -- of living snakes, lizards, and a third related group of scaly reptiles, the amphisbaenians. The team analyzed these data using several statistical methods to determine how each species is related to the others. "Although these genes have the same functions in each species, there are small differences between the species -- mutations -- that have developed over time," Vidal explains. Comparisons of these evolutionary differences resulted in a family tree of squamates that Hedges says is almost completely different from the version that has appeared in textbooks for the past hundred years. The family tree in use now is based primarily on comparisons of certain physical structures, known as morphological characters--like the shape of a specific bone.

"The current textbook version of the family tree of reptiles places the iguanians, which is a huge group of 1,440 species of primitive-looking lizards, at the base of the tree -- but the iguanians now are near the top of our new tree in the new Toxicofera group, which we call the venom clade," Vidal explains. In addition to the new venom character, Vidal and Hedges discovered other physical traits whose importance in providing visible clues to the species' close genetic relationships had been overlooked before. For example, among the lizards and snakes that lay eggs, all the species above a certain point in the new tree have one egg tooth and all those below that point have two egg teeth. "In the old arrangement, using the number of egg teeth as an evaluating characteristic didn't make sense, but in the new arrangement it makes perfect sense," Vidal says. "If this new tree is correct, all the morphological characters that traditionally have been used to identify similarities between species will need to be reevaluated to understand how these traits evolved."

According to Vidal and Hedges, the reason why the old and new family trees are so different is because they are based on different ways of gauging the relationships between species. The old tree is based primarily on morphology -- comparisons of certain characteristics of the animals' physical structure -- which can change considerably when a species adapts to changing conditions. For genealogy research this can be a problem if two unrelated species change in the same way, resulting in false evidence of relationships. The new tree is based exclusively on comparisons of the molecular structure of the animals' genes. "Although the molecular changes in the genes can occur quickly and slowly, and can change in response to the conditions in which the animal lives, those adaptive changes are limited to a small part of the gene. Most of the gene carries a genealogical signature which reveals the evolutionary history of the species" Hedges explains. Many of the groups on the existing, morphological, family tree were named for physical characteristics that no longer apply to the groups on the new tree. For example, as a result of the reorganization, a huge group of lizards -- the iguanians, which have soft tongues and number more than 1400 species -- moved from near the bottom of the old tree into a grouping near the top of the new tree among squamates, which have hard tongues. As a result, Vidal explains, "We found we needed to replace many of the old names, like the one that referred to the texture of the tongue, because they no longer have any valid meaning in the new tree."

Among the new names are Bifurcata, which in Latin that means "split," for species with a split tongue; Toxicofera, which means "toxic animals," for species that have venom, Unidentata, which means "one tooth," for species with one egg tooth; Episquamata, which means "top squamates," for the iguanians and other species in this group near the top of the new tree; Laterata, which means "tile-like," for a group of lizards and legless reptiles whose scales are shaped like squarish tiles instead of the half-circle-shaped scales common to snakes and other lizard species.

"Because the current tree has been widely accepted for nearly a century, I think there is going to be a delay of maybe a few years before the general scientific community gets used to the new tree," Vidal says. "If other research groups working in this area find the same pattern with additional genes, then I believe the scientific community may accept these results more quickly."

###

This research was supported by the National Aeronautics and Space Administration's Astrobiology Institute, Penn State, the National Science Foundation, and the National Museum of Natural History of France.

NOTE: This press release concerns research reported in the current issue of two scientific journals (published on 16 November): Nature, published in the United Kingdom, and C. R. Biologies, published in France.

[Omitted some contact information at the end of the article]

[PatrickHenry]

This should be interesting.

[PatrickHenry]

Evolution Ping The List-O-Links

A conservative, pro-evolution science list, now with over 320 names. See the list's explanation, then FReepmail to be added or dropped. To assist beginners: But it's "just a theory", Evo-Troll's Toolkit, and How to argue against a scientific theory.

[Doogle]

..top of the tree eh?, Ok there's some resemblance between the that lizard and the ex's mom.


Doogle

[The Sons of Liberty]

The picture in the article strongly resembles Carville.

[DHak]

what the F@#$ is a amphisbaenians?

[swmobuffalo]

Boy are my husband's biology students gonna be mad.

[Red Badger]

Just when ya figger out where ever thin' is, they go and change it on ya.........

[Junior]

The CrevoSci Archive Just one of the many services of Darwin Central "The Conspiracy that Cares"

• PatrickHenry's famous List-O-Links
• Webster's On-Line Dictionary:  Creationist

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CrevoSci threads for the past week:

1. 2005-11-23 Genealogy of scaly reptiles rewritten by new research
2. 2005-11-22 10 Biology Textbooks Fail Basic Standards
3. 2005-11-22 "Bacteria which sense the Earth's magnetic field (""Simple"" organisms?)"
4. 2005-11-22 Charles Krauthammer's Ignorant Essay on Design
5. 2005-11-22 Evolution and medicine (Evolution is not operational science)
6. 2005-11-22 Getting a Leg Up on Land [Evolution]
7. 2005-11-22 Homo Erectus Ate Crunchy Food
8. 2005-11-22 Shaking the Foundation of Faith
9. 2005-11-22 The food you eat may change your genes for life
10. 2005-11-22 Those Defensive Darwinists
11. 2005-11-22 U. of Kansas Offers Creationism Study
12. 2005-11-21 Denominational Creationism Continues its Destructive Course
13. 2005-11-21 Evangelicals and Environmentalism
14. 2005-11-21 Why People Hate Economics (lining up a billiard shot vs. getting a prom date)
15. 2005-11-20 Charles Darwin: Evolution of a Scientist [Newsweek's cover story]
16. 2005-11-20 Evolution and the Pope
17. 2005-11-20 Past yields few clues for predicting flu
18. 2005-11-20 Scientists 'see new species born'
19. 2005-11-20 Scientists Show We've Been Losing Face For 10,000 Years
20. 2005-11-20 University Is Accused of Bias Against Christian Schools
21. 2005-11-19 Evolution debate hits the beer aisle
22. 2005-11-19 Seeing Mountains in Starry Clouds of Creation
23. 2005-11-19 The Darwin exhibition frightening off corporate sponsors
24. 2005-11-19 The Singularity Is Near
25. 2005-11-19 Vatican Official Refutes Intelligent Design (ZOT!!! We still burn trolls).
26. 2005-11-18 Dinosaurs in India may have fed on grass
27. 2005-11-18 Early Earth Likely Had Continents, Was Habitable, According To New Study
28. 2005-11-18 Exhibit on Darwin creates Bush bash at museum gala
29. 2005-11-18 Geneticists claim ageing breakthrough but immortality will have to wait
30. 2005-11-18 Indian Dinosaurs Were Vegetarians
31. 2005-11-18 Intelligent Design: Kansas Teachers Guide
32. 2005-11-18 On the Origin of Evolution
33. 2005-11-18 Peril in Paradise: Why Young-earthers Emotional 'No Death Before Adam' is just that: Emotion
34. 2005-11-18 Quintuple Bond Synthesized
35. 2005-11-18 Study Challenges View on Aging Research [amazing implications]
36. 2005-11-18 The Origin of Speciousness (Darwinism is an intrinsically atheistic theory. If...)
37. 2005-11-18 Vatican Official Refutes Intelligent Design
38. 2005-11-18 Vatican Official Refutes Intelligent Design
39. 2005-11-18 We're not in Kansas anymore (Krauthammer slams Intelligent Design)
40. 2005-11-18 Why intelligent design proponents are wrong.
41. 2005-11-17 Backing out possible, not simple [Dover trial aftermath
42. 2005-11-17 Dung Reveals Dinosaurs Ate Grass
43. 2005-11-17 Gene turn-off makes meek mice fearless
44. 2005-11-17 Is opposition to ID based upon science or politics?
45. 2005-11-17 New York Times Deceives Public About Kansas Definition of Science
46. 2005-11-17 Phony Theory, False Conflict
47. 2005-11-17 Prehistoric Lizard Called Historic Link
48. 2005-11-17 The Assembly of Protocells (Science/Ethics alert: engineering new life forms)
49. 2005-11-17 The Flawed Philosophy of Intelligent Design
50. 2005-11-17 The Food You Eat May Change Your Genes For Life
51. 2005-11-17 The risks of cousin marriage (Pakistanis in the UK)

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CrevoSci Thread Count, 2005 YTD:  1164

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On This Date in CrevoSci History

1. 2004-11-23 Evolution vs Creationism
2. 2004-11-23 Grand Canyon Science-Creationist Face-Off
3. 2004-11-23 Intellectuals Who Doubt Darwin
4. 2003-11-23 The 'Stick Man' Cometh (Kennewick Man's Cousin?)
5. 2003-11-23 VANITY Need help debunking Creationist Stevin A. Austin
6. 2003-11-23 Who Were The Si-Te-Cah
7. 2001-11-23 Dino asteroid led to 'global devastation'
8. 1999-11-23 Is the raqiya‘ (firmament) a solid dome?

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Longest CrevoSci Thread Ever

• 2002-12-11 Evolution Disclaimer Supported (6,880 replies)

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Lost CrevoSci Battlefields (Pulled or Locked Threads)

1. 2005-11-15 'Perception' gene tracked humanity's evolution, scientists say
2. 2004-04-27 Stop Teaching Our Kids this Evolution Claptrap!
3. 2003-10-29 The Mystery of the Missing Links (Intelligent Design vs. Evolution)
4. 2003-10-27 Physics Nobelist Takes Stand on Evolution
5. 2003-10-23 Gene Found for Obsessive Compulsive Disorder
6. 2003-10-21 Artificial Proteins Assembled from Scratch
7. 2003-09-23 Solar System Formation Questions
8. 2003-09-17 Agreement of the Willing - Free Republic Science Threads
9. 2003-07-18 Unlikely Group May Revive Darwin Debate [Evolution v. Creationism]
10. 2003-07-02 Unlocking the Mystery of 'Unlocking the Mystery of Life'
11. 2003-06-26 Darwin Faces a New Rival
12. 2003-06-06 Amazing Creatures
13. 2002-09-13 Oldest Known Penis Is 100 Million Years Old
14. 2002-04-10 (Creationists) CRSC Correction
15. 2001-11-10 Alabama to continue biology textbook warning sticker
16. 2001-11-06 Warming makes mosquito evolve, University of Oregon scientists find
17. 2001-08-28 The Ultimate Creation vs. Evolution Resource [6th Revision]
18. 2001-08-26 A Scientific Account of the Origin of Life on Earth [Thread I]
19. 2001-01-13 A Christian Understanding of Intelligent Design
20. 2000-11-15 Evolutionism Receives Another Hard Blow
21. 2000-10-10 Another Lost Generation?
22. 2000-08-30 Evil-Ution
23. 1999-11-14 Creationism's Success Past 5 Years: (Gallup: 1 in 10 hold secular evolutionist perspective)

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CrevoSci Warrior Freepdays for the month of November:
 

2000-11-29 An.American.Expatriate 2000-11-10 AncientAirs 2000-11-21 AndrewC 1998-11-18 angelo 2000-11-10 beavus 1999-11-22 Blood of Tyrants 2003-11-26 blowfish 2004-11-08 CarolinaGuitarman 1997-11-28 cd jones 2005-11-18 chachachia 2000-11-09 chance33_98 2001-11-30 claptrap 2001-11-16 CobaltBlue 2005-11-10 culturewars 2002-11-21 DannyTN 2004-11-16 DaveLoneRanger 1997-11-30 Ditto 2001-11-16 dmz 2000-11-11 Ernest_at_the_Beach

2000-11-02 Exigence 2000-11-02 Exit 109 2004-11-05 FeeinTennessee 2000-11-22 FFIGHTER 2000-11-12 ForGod'sSake 2001-11-07 FourtySeven 2000-11-15 freespirited 2005-11-16 glow-worm005 2000-11-10 Godel 2004-11-06 GreenOgre 2004-11-03 Grey Rabbit 2000-11-04 harbinger of doom 2000-11-28 HiTech RedNeck 1999-11-05 Ichneumon 1998-11-13 jennyp 2005-11-10 jodiluvshoes 1998-11-25 Junior_G 2002-11-17 Just mythoughts 2004-11-11 kaotic133

2005-11-14 knowseverything 2000-11-28 leadpencil1 2003-11-18 little jeremiah 2004-11-15 lodity 1998-11-18 malakhi 2000-11-19 Mike Fieschko 2004-11-24 mista science 2003-11-09 MplsSteve 2000-11-06 mrjeff 1999-11-05 muleskinner 2003-11-17 Nathan Zachary 2002-11-12 NCLaw441 1999-11-25 Nebullis 2000-11-13 NYer 2000-11-24 old-ager 2001-11-26 OrthodoxPresbyterian 2004-11-03 PajamaHadin 2000-11-10 Patriotic Teen 1998-11-01 Pharmboy

2000-11-11 P-Marlowe 2000-11-16 presidio9 1999-11-08 Pyro7480 2002-11-14 Remedy 2000-11-30 Right Wing Professor 2004-11-18 rightwinggoth 1998-11-15 rob777 1998-11-04 RobRoy 2004-11-01 SeasideSparrow 2004-11-05 shadowfighter 1999-11-16 TerP26 2004-11-13 This Just In 2000-11-04 TigerTale 2004-11-11 untrained skeptic 2004-11-21 VictoryGal 2001-11-25 Vote 4 Nixon 2000-11-05 will of the people 2003-11-29 woodb01

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In Memoriam
Fallen CrevoSci Warriors:

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1LongTimeLurker Ahriman ALS angelo Area Freeper Aric2000 Askel5 Asphalt biblewonk bluepistolero churchillbuff claptrap codebreaker Con X-Poser ConservababeJen dbbeebs Destro DittoJed2

dob Ed Current f.Christian followerofchrist freeparella general_re goodseedhomeschool gopwinsin04 gore3000 IllumiNOTi JediGirl JesseShurun JethroHathaway jlogajan JoeSchem Justice Avenger Kevin Curry kharaku

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Phoroneus pickemuphere ReasonedThought ret_medic RickyJ SeaLion Selkie Shubi SplashDog Stingy Dog The Loan Arranger Tomax tpaine Truth666 twittle Unalienable WaveThatFlag xm177e2

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Bring back Modernman and SeaLion!

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Glossary of Terms

Assumption: Premise: a statement that is assumed to be true and from which a conclusion can be drawn; "on the assumption that he has been injured we can infer that he will not to play" Belief: Any cognitive content (perception) held as true; religious faith Crevo:  Creation vs. evolution CrevoSci:  Creation vs. evolution/Science CrevoSci Warriors:  Those who take part on CrevoSci threads Data: factual information, especially information organized for analysis or used to reason or make decisions Dogma: a religious doctrine that is proclaimed as true without proof Fact: When an observation is confirmed repeatedly and by many independent and competent observers, it can become a fact Freepday:  The day a Freeper joined Free Republic Hypothesis: A tentative theory about the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena; "a scientific hypothesis that survives experimental testing becomes a scientific theory"; "he proposed a fresh theory of alkalis that later was accepted in chemical practices" Impression: A vague idea in which some confidence is placed; "his impression of her was favorable"; "what are your feelings about the crisis?"; "it strengthened my belief in his sincerity"; "I had a feeling that she was lying" Law: A generalization that describes recurring facts or events in nature; "the laws of thermodynamics" Observation: Any information collected with the senses Theory: A well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena; "theories can incorporate facts and laws and tested hypotheses"; "true in fact and theory"

[Antonello]

what the F@#$ is a amphisbaenians?

According to the Encyclopædia Britannica:

The amphisbaenians form a little-known group of reptiles. Because they are burrowers and live almost entirely underground, they are seldom seen. The one species in the United States, Rhineura floridana, is found in some parts of Florida; a number of species occur in other regions of the world, especially in South America and Africa.

[jbloedow]

Wow, with all these errors that have been taught to students for over a century by evolutionary biologists, it gives a new meaning to "science fiction".

Nevermind, I'm sure they've got it right now.

Seriously, I can't believe teaching evolutionary relationships based on morphological similarities despite no supporting evidence from molecular biology was passed off as serious science. Perhaps there was a lack of professional skepticism in this community? Nahhhhhhhhh.....

[Junior]

Seriously, I can't believe teaching evolutionary relationships based on morphological similarities despite no supporting evidence from molecular biology was passed off as serious science.

Genetic research is still relatively new. Up until recently, the only way to determine relatedness was through study of the morphology of the species.

[dread78645]

The picture in the article strongly resembles Carville.

Venomous lizard. Yep.

[furball4paws]

Always have known that genomics and gene sequencing data are going to revise some groups based simply on appearances. When the science guys are done the phylogenetic trees are going to be really solid. During the transition, things could get interesting and we might even see a few scientists come to blows over what means what.

[PatrickHenry]

I'm anticipating a number of similar posts from anti-evos, blathering about how this new work shows that those evolution guys don't know anything. However, the this that they're ballyhooing (comparisons of the molecular structure of the animals' genes) is exactly what demonstrates our relationship to apes.

New item in The List-O-Links that may be relevant:

Life's Big Instruction Book, or, Molecular Genetics by Analogy. Great tutorial.

[microgood]

What a week.

First we find out dinosaurs did eat grass.
Then we find out grass is 70 million years old instead of 55.

And now this.

At least the status of turkeys is remaining steady although I would not rule out some bombshell to be released tomorrow.

[Antonello]

Wow, with all these errors that have been taught to students for over a century by evolutionary biologists, it gives a new meaning to "science fiction".

I suppose evolutionary biologists could take the biblical approach and ignore any new evidence that contradicts accepted ideas, but that would make it dogma.

This is yet another example of why the ToE is not a religion, despite the fervent desires of fundamentalists to the contrary.

[furball4paws]

Turkeys are feathered snakes. It's common knowledge. Where've you been?

[microgood]

Turkeys are feathered snakes.

It actually kind of makes sense the way they bob their heads like a snake striking at a target.

[BlueYonder]

There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact. - Mark Twain

[furball4paws]

I know that tomorrow morning, I'm going to pull a snake out the turkey's butt, cook it up with the heart and liver and my dogs wil feast on it later. That's enuf for me.