Something puzzling me regarding testing of evolution

Sunstar said:
If you can quote me it might help, otherwise reffering to one word out of a whole load in this thread will not jog my memory sufficiently.
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It is not difficult to go back to the top of the thread and read what you have written.

Do so, and quit playing incapacitated.
 
Simon39759 said:
Actually, it does.
For example, you take a pathogen and culture it for a few generations, odds are its going to loose virulence, basically, accumulate mutations in the virulence genes it is not using.
Yet, inject it back into an organism for a few generations and the virulence will be back, basically, it will now be under selective pressure to be virulent, while it was not before.
The term often employed is 'revert' to virulence.

In the case of whales, of course, this can not be employed, as the mammalian lineage had been terrestrial for so long that the whales' ancestors had loss any trace of the genes in question (or, more likely, these genes had evolved into something quite different and unrecognizable), so the whales had to 're-invent' all the genes involved in the aquatic life-style...


Also, mammals are still fish, 'once you are in the club, you can't get out' as Dr. Davies said in this week's episode of 'Monster talk' (soon on the internet near you).
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This I did not know. Thanks.

The term 'revert' may have meaning in evolutionary theory, but not the meaning that I think she ascribed to it.
 
MG1962 said:
We currently dont have the technology to clone extinct creatures, even when viable DNA is avaliable. We have some excellent samples of DNA from the Tasmanian Tiger, which only went extinct in the 1930's - To date all efforts to bring this animal back have failed.
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Have there been any efforts to bring this animal back aside from some over-hyped press releases by, I think, Tim Flannery?

As it stands I don't think "we" have managed to clone a recently dead animal yet, all cloning has involved intact nucleus from a living cell.
 
Wowbagger said:
On a the topic of cloning, here is a question I would like to throw out, here:

If we know that cellular development is primarily regulated, or (in an approximate sense) "determined" by DNA, would it be possible to reverse engineer what the DNA was like, based on anything else we know about the fossil's cellular development and structure?

I think this question is in the spirit of the opening post.
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Well, you can isolate a protein and then back translate it and it gives you an idea of the DNA sequence.
It's done quite often but is has its limit for a couple of reasons: mainly, the protein and the RNA coding for it often go through a series of post-transcriptional and post-translational changes, removing the introns and changing the protein a bit.
However, it gives you an idea of what the DNA sequence look like and, from there, you can go and look through the genome until you found something similar. Then, I'd imagine, you can clone and express this sequence and see if you end up with the same end-product...

Now, what you are asking about is doing so at a higher level, starting not from a single protein but from an actual organism. This, clearly would compound the problem exponentially, you'd have tenth of thousands of genes to account for at the same time, interact with each other in endless and varying ways...
And, in your case, you'd probably not have a model to look at like we had for the protein, even compounding the problem further.

So, to answer your question, no. It's not theoretically impossible but it is way beyond what we can expect to achieve in the foreseeable future.
 
Complexity said:
This I did not know. Thanks.

The term 'revert' may have meaning in evolutionary theory, but not the meaning that I think she ascribed to it.
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I agree; 'revert' is only there for genes that evolution has not yet buried under the weight of mutations, so, recent evolutionary events.
 
Mr. Sunstar,

I think much of the difficulty you are experiencing with other posters is based off of the idea that DNA somehow exists in totality, more specifically you refer to "DNA" quite often without any further qualifiers. This gives the impression that you reference an entire genome of an organism, in which case yes cloning would be possible (we can clone a sheep, for example, and at least theoretically a human now that the genome has been mapped).

The problem with this, quite simply, is that we don't have a genomic map of these 'ancient organisms' from which to clone. It's roughly analogous to finding a lost Aztec city - if you have a map it's quite simple, but without one you're reduced to blindly wondering through the jungle in the hope you find it before supplies (money) run out. And on the odd chance you do stumble onto ruins, determining if they're the Aztec ones you were seeking will take up even more supplies.

It would be nice if the genome map could be pulled from fossils, but the major difficulty here is that degredation of DNA is random - there is no way to 'work backwards' through this veil of uncertainty in an isolated instance.

Using the omniscience granted by a hypothetical example, imagine that a very simple ancient organism had a genome map as follows: ATTACGGCTAATCG. Now imagine that this organism dies and begins to decay over time. Several million years later it is found by an inquisitive archeologist and its genome is mapped. Due to decay, and substituting dashes for bases whose identity has been lost to time, the genome map drawn from the fossil looks like this: AT-A--G-TA---G.

Modern science has identified the pairing used by the DNA bases, so we can logically rederive some of the genome. Employing parentheses to denote the deduced identity of the knowable bases, we get the following map: AT(T)A--G(C)TA--(C)G. These deductions are a certainty.

This is pretty good work so far, the archeologist/geneticist combo is only missing two base pairs - but the problem is that they have no way of determining the precise identity of these pairs, or even one base. Lacking our omniscience, they have essentially been made fools of by time - they have no data upon which to hypothesize the construction of the missing pairs. It's this lack of data caused by degredation that is the major roadblock in cloning ancient organisms.

One of the ways to get past this roadblock is simply to get more data - different fossils sharing the same characteristics might be of the same species but have degraded differently, permitting identification of another base pair. This sort of research is perpetually ongoing but is based upon both finding a fossil (the work of years, occasionally lifetimes) and identifying its genome (probably the work of months). Science here proceeds at a snail's pace, but frankly having gotten this far alone is impressive.

~ Matt
 
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little grey rabbit said:
Have there been any efforts to bring this animal back aside from some over-hyped press releases by, I think, Tim Flannery?

As it stands I don't think "we" have managed to clone a recently dead animal yet, all cloning has involved intact nucleus from a living cell.
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Everytime there has been a break through in cloning, various research groups have looked at the implications for bringing the tiger back. An article from 2009 seems to suggest that from a DNA point of view they may not actually be enough material to make a serious effort worthwhile.

There was always a lot hope involved because when the last tiger died in 36' they knew it was the last and preserved as much of it as possible
 
Sunstar said:
From one layman to another, i don't pretend to know things i don't. But i certainly didn't say originally that the whale was a fish. And even if i did, it wasn't the point of the OP.
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Yes you did. You said the whale was a half-fish half-mammal creature that decided to go back to being a fish.

So, instead of getting side tracked with all this ********, please respond to the OP.
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Maybe you should stop flaunting your ignorance with one-line troll posts and people won’t feel so obligated to smack some sense into you.
 
Sorry, but I read "evolutionary theories", and my eyes glazed over. Then, "devolved back into fish..". I dozed off. OH! Jonah and the big fish!
 
Sunstar said:
From one layman to another, i don't pretend to know things i don't. But i certainly didn't say originally that the whale was a fish. And even if i did, it wasn't the point of the OP.
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Yes you did.
Sunstar said:
We know that once there were mammals that devolved back into fish
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Sunstar said:
Correction, it was not that whales evolved from mammals, it was that they started out as fish and became semi mammals and then reverted back to fish.
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So, instead of getting side tracked with all this ********, please respond to the OP.
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Maybe you should stop flaunting your ignorance with one-line troll posts and people won’t feel obligated to smack some sense into you.
 
Wowbagger said:
I imagine it would be like trying to reverse engineer the recipe for a cake, when all you have are some left-over crumbs. Probably worse than that, even.
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Far, far worse than that, for that crumb is representative of the rest of the cake (leaving fillings and frosting aside), while a DNA fragment would represent only a small part of a very large sequence that can't be inferred from the fragment.
 
Wowbagger said:
I imagine it would be like trying to reverse engineer the recipe for a cake, when all you have are some left-over crumbs. Probably worse than that, even.
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More like trying to re-write The Lord of the Rings from a few torn scraps of paper.
 
Elizabeth I said:
Your real name is Sunstar? Do you have brothers named River, Leaf and Joaquín?
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That made me laugh!

Btw, you don't happen to be from "Hogtown", do you?

I'm still waiting for the Aleca's Attic material to get released.
 
MG1962 said:
Everytime there has been a break through in cloning, various research groups have looked at the implications for bringing the tiger back. An article from 2009 seems to suggest that from a DNA point of view they may not actually be enough material to make a serious effort worthwhile.

There was always a lot hope involved because when the last tiger died in 36' they knew it was the last and preserved as much of it as possible
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If you said everytime there is a break-through in cloning some journalist rings up a rent-a-quote media hungry biologist, then I might agree with you.

IIRC, the samples consist of skins preserved in alcohol. It is conceivable that using new sequencing technology an entire genome could be constructed from this material - despite degradation in DNA (conceivable, I am not sure if it is really possible).

Then all we need to do is wait until technology has progressed to create chromosomes from pure sequence data alone and a method to insert these chromosomes into an egg. The 2nd is conceivable; the 1st will involve unforeseeable giant leaps in technology.
 
Complexity said:
Wowbagger said:
I imagine it would be like trying to reverse engineer the recipe for a cake, when all you have are some left-over crumbs. Probably worse than that, even.
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Far, far worse than that, for that crumb is representative of the rest of the cake (leaving fillings and frosting aside), while a DNA fragment would represent only a small part of a very large sequence that can't be inferred from the fragment.
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That's true.

Though, technically, I was talking about not using DNA fragments.

Basically: Inferring what the DNA would be like from any other properties of the cells that we can determine.

A cell would be a like a crumb of the cake, representing, to a certain degree, various factors that apply to the whole life-form.
I acknowledge that cells do differentiate more than typical cake crumbs - However, I suppose certain properties would remain consistent throughout.

I suspect that explaining why this form of cloning would be next-to-impossible would be very instructive to the questions posed in this thread.
 
Piggy said:
That made me laugh!

Btw, you don't happen to be from "Hogtown", do you?

I'm still waiting for the Aleca's Attic material to get released.
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Don't know where (what?) Hogtown is. I'm not that cool.
ETA: but I lived in Tempe, right outside Phoenix, for three years.

Re: Aleka's Attic - Don't know if this counts or not: http://www.myspace.com/alekasatticzero

I always wondered where Joaquín came from. I mean, Joaquín?
 
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