Biologists find that red-blooded vertebrates evolved twice, independently

July 27, 2010
Sea lamprey.

( -- Nature, in all its glory, is nothing if not thrifty.

Through the process of natural selection, it finds new uses for existing features, often resulting in what is known as convergent evolution -- the development of similar biological traits in different orders of animals, such as powered flight in birds and bats.

Now, research by University of Nebraska-Lincoln biologists has found convergent evolution of a key physiological innovation that traces back through the two deepest branches of the vertebrate family tree.

A team led by Jay Storz (prounounced storts), assistant professor of biological sciences, analyzed the complete genome sequences of multiple vertebrate species and found that jawless fishes (e.g., lampreys and hagfish) and jawed vertebrates (pretty much everything else, including humans) independently invented different mechanisms of blood-oxygen transport to sustain aerobic metabolism.

Specifically, comparative analysis of their gene repertoires revealed that the ancestors of jawed and jawless vertebrates co-opted completely different precursor proteins to serve as oxygen-transport hemoglobins, the respiratory proteins that give blood its red color. The jawed and jawless vertebrates separated about 500 million years ago, late in the and about 30 million years after the first vertebrate precursors (the chordates) show up in the .

"What we've discovered is that similar physiological problems called forth similar solutions in different branches of the vertebrate family tree," Storz said. "For example, jawed vertebrates invented one type of hemoglobin as an oxygen transport protein, whereas the other main vertebrate lineage, the jawless fishes, represented today by lampreys and hagfish, came up with their own independent solution for the same physiological problem."

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That problem was size, which can matter greatly in natural selection when it comes to staying alive to find and keep a mate and to produce and protect offspring. Many animals, such as insects, get by without any type of oxygen transport protein in their circulation because they're small enough that they can rely exclusively on the passive diffusion of oxygen through what's called the tracheal system. But that process puts an upper limit on body size, which is why insects don't grow to much more than 3 inches long.

The evolution of hemoglobins as oxygen transport proteins a half billion years ago opened up new opportunities for the evolution of aerobic metabolism, and thereby facilitated the evolution of increased body size and internal complexity in animal evolution. The UNL study showed that nature found more than one way to cross that evolutionary threshold.

"The oxygen transport hemoglobins that were independently invented by the jawed and jawless vertebrates are functionally quite similar, but there are numerous structural details that belie their independent origins," Storz said. "These small but telling differences reflect the fact that the proteins evolved their oxygen-transport function from different ancestral starting points.

"The discovery that the hemoglobins of jawed and jawless vertebrates were invented independently provides powerful testimony to the ability of to cobble together similar design solutions using different starting materials."

The findings were reported in the July 26-30 online edition of the Proceedings of the National Academy of Sciences.

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4.2 / 5 (9) Jul 27, 2010
Really makes you wonder what the real possibility space is for organisms. There's enough evidence of convergence to make me think alien life may not be as wildly different from our own as we think.
Jul 27, 2010
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5 / 5 (3) Jul 28, 2010
That would depend on how different you think life might be. Look at just how many of the earliest animal phyla were worms of one kind or another. Nearly all animal life started as some kind of worm.

A front and back and a top and bottom seem to be the basis for all the life that has much control of how it goes about doing things. A mouth at one end and an exit at the other. A preferred side to the bottom and now you have bi-lateral symmetry.

I expect that there will be a lot of convergence. Just not as much as on Star Trek where the budget constrains life and not natural selection.

Jul 28, 2010
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5 / 5 (9) Jul 28, 2010
kevinrts, are you trolling?
According to wikipedia, it's 19 times more efficient to release energy with oxygen than without (aerobic versus anaerobic metabolism). In a crazy oversimplification that would give an organism with a oxygen-transporting molecule 19 times better chances against the other organism without the molecule: faster growth, stronger.

These co-evolution examples are something like the most awesome demonstrations of evolution at work. You can build a molecule with a certain function in a huge number of ways, it is only likely that two species will find a different solution, although it takes time. And I guess our hemoglobin today is not the same as 500 million years ago; it's been evolving and improving ever since, but maybe a molecular biologist can elaborate on that, instead? :)

5 / 5 (4) Jul 28, 2010

It's NOT the same structure...that's what the article is saying. Its DIFFERENT hemoglobin. See also Horseshoe crabs [wikipedia]:horseshoe crabs do not have hemoglobin in their blood, but instead use hemocyanin to carry oxygen. Because of the copper present in hemocyanin, their blood is blue.

The point is that there are all of these DIFFERENT ways that are used by life to transport oxygen. It's only "convergent" that horseshoe crabs, jawless and jawed vertibrates all use "blood" but that blood is different.

Like a car and Semi...both 'converged' to use internal combustion piston engines...but use gasoline or diesel either of which won't really run in the other.
5 / 5 (5) Jul 28, 2010
And, 'convergence' doesn't blow away happens everyday. Scientists, chefs, mechanics, parents, teachers develop completely independent solutions to similar problems. Sometimes Identical solutions are discovered/invented independently, and sometimes the solutions are completely different.

This isn't hand-waving, and it's no less miraculous. I think most scientists are blown away that under whatever rock we turn over there is a novel solution to some problem...that evolved out of some previous solution and problem.
4.8 / 5 (6) Jul 28, 2010
Kevintrs - If life were designed by an intelligent designer, why would that designer design two similar but different oxygen-carrying systems in vertebrates, as well as a third somewhat similar system for invertebrates such as horseshoe crabs?

Science does not address whether there is no god, one god or many gods. If a god exists, then what science is doing is studying god's work - surely you can respect that.
And studies of life, such as this one, show that if a god is in charge of creating life, that god's favorite tool is evolution.

Now who exactly put you in charge of deciding which tools god is allowed to use?
4.6 / 5 (11) Jul 28, 2010
Make you really wonder just when people will start to realize just what a big con the whole theory of evolution is!

Would you just keep your stupid ideas to yourself. We don't come to your bible study and start spreading logic and reason during story time. We come to this site to escape the humans like you we are forced to co-habitat with until we can migrate off this rock and away from its religious waste products.

Please, if you or your family are ever afflicted with a terminal disease that can be cured with any medical treatment that stemmed from genetic analysis, please decline, pray, and move on, if you catch my lingo.
Jul 31, 2010
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5 / 5 (4) Aug 01, 2010
q]Make you really wonder just when people will start to realize just what a big con the whole theory of evolution is! Never. However some people will keep believing in fantasies. Others will spread those fantasies.

And some like you will remain actively ignorant since you refuse to learn anything despite the many times your errors have been pointed out. With evidence. You have NO evidence to support you. Just an ancient written long ago by men that wrote done stuff told by men that mostly couldn't read. And those that could read had no eduction outside of their religion. They had no choice about being ignorant.

What is your excuse for remaining as ignorant as them on biology?

More reality to come
5 / 5 (3) Aug 01, 2010
Whenever no possible explanation can be found as to why the same structures are seen in seemingly completely unrelated organisms the convergent card is played
Which has been explained to you MANY times that convergent evolution IS the explanation.

Evolution is a process that cannot NOT happen. Mutations happen, even some Creationists are aware of this. The environment selects which mutations survive and which die out. Similar environment will kill off similar mutations and the mutations that survive MAY be similar as well. For instance in most of the world canines are enlarged in many species and very few species have enlarged teeth in the lower jaw. In Australia most of the species went the other way with enlarged teeth in the lower jaw to do the work of canines. Similar but not identical.

Continuing reality for an unreceptive non-reader
5 / 5 (4) Aug 01, 2010
Nobody spares a thought for just what a miraculous event that convergence
Actually I have. You are the one that refuses to think about how convergence can occur. You just claim goddidit and then post what is nearly the same nonsense as the last time.
Convergence basically blows away the single ancestor idea in just so many easy words
In so many easy words you spout nonsense. It is LIKELY though not certain that all life started from a single ancestral self or co-reproducing molecule. Since then there has just a tad of divergence into multiple species that THEN have a possibility of converging on similar solutions to the problems of survival.
- but nobody's complaining as long as the religion of evolution keeps on rolling.
False. YOU sure are complaining about a non-existent religion. Apparently you are incapable of noticing that it is possible to think in a non-religious manner.

Reality will return In a Quantum of Scientific Thinking as we are limited to quantum posts
5 / 5 (2) Aug 01, 2010
I have thought this out quite thoroughly, as have many others and it is just plain false to claim that everyone you disagree with is actively ignorant much like you only with a different religion. We go on evidence and reason not ancient books written by ignorant men.

I am tempted to just save a copy of this and fill in the quotes from Kevins next post. It won't make a bit of difference to the reply as Kevin never says anything I haven't already seen. The same ignorant remarks every bloody post.

And nearly every single time he scarpers off. Doesn't even have the courage to stay and support his claims.

5 / 5 (1) Aug 01, 2010
To the Creationists , there is a simple answer to the GOD hypothesis -
Life will always find a way .

Before the present Oxygen rich environment which we now enjoy , billions of years back , life survived with Sulphur as the basis instead of Oxygen. There are still some extremeophiles which use sulphur to get energy instead of Oxygen.

That ability to "breathe" Sulphut wasn't god given. In fact life always evolves to adapt itself to the environment. You could argue that God is not a singularity, rather god is everywhere , perhaps god is life itself ?

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