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Author Topic:   Is Evolution Reversible
Taq
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Posts: 7673
Joined: 03-06-2009
Member Rating: 2.6


Message 16 of 49 (509311)
05-20-2009 11:30 AM
Reply to: Message 1 by doc
05-17-2009 7:08 PM


doc writes:

Evolution doesn't have a direction so surely it is possible for it to go backwards?

French and the other Romance Languages "evolved" from Latin. Would you expect the French language to slowly change over time so that it sounds more and more like Latin? Of course not, right? The evolution of biological life is no different.


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Blue Jay
Member (Idle past 775 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 17 of 49 (509353)
05-20-2009 6:37 PM
Reply to: Message 9 by RAZD
05-18-2009 6:30 PM


Hi, RAZD.

RAZD writes:

And some of them gained wings (red). And diversified.

And some of them lost wings (blue again). And diversified.

And one of those gained wings again (Lapaphus parakensis, below, red again).

Actually, you've said this backwards: red is wingless and blue is winged.

So, you've got a wingless common ancestor of walking sticks, several different lineages of walking sticks regaining their wings, and one of those from a winged clade losing its wings again.


Click to enlarge

Just a clarification note: the numbers provided at each fork in the tree are bootstrap values. A bootstrap value of 100 means that all simulations run agreed at that point.

So, there is pretty unequivocal support for the wingless Lopaphus parakensis being derived from within the winged clade.

Edited by Bluejay, : Added picture link for clarification


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


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doc
Junior Member (Idle past 3497 days)
Posts: 11
Joined: 05-17-2009


Message 18 of 49 (509754)
05-24-2009 11:40 AM
Reply to: Message 16 by Taq
05-20-2009 11:30 AM


Taq writes:

French and the other Romance Languages "evolved" from Latin. Would you expect the French language to slowly change over time so that it sounds more and more like Latin? Of course not, right? The evolution of biological life is no different.

Language "evolution" and the evolution of living things is not the same and it's not really a valid comparison.


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doc
Junior Member (Idle past 3497 days)
Posts: 11
Joined: 05-17-2009


Message 19 of 49 (509757)
05-24-2009 11:57 AM
Reply to: Message 14 by RAZD
05-19-2009 8:17 PM


RAZD writes:

You can turn a feature off by blocking or removing any part of the development critical to the formation of wings, and this would likely leave you with the same original feature that the wings evolved from, plus some genes inherited while winged that are not removed. Thus if a new by-pass is evolved to get around the blocked or removed part it would allow necessarily similar wings to evolve - it would be preadapted to form similar wings.

RAZD writes:

How much is "significantly different"?

Would it not still be working from the same basic features that were there when the wings first evolved? If I remove a sprinkler from the end of my hose I am still capable of watering the lawn, and I can put another sprinkler on the same hose.

I'm not sure whether your example was over 50M years or 50k years as you've suggested both.

However if it's 50M then I'd suggest that it's very unlikely for a wing to re-evolve. When a feature is "lost" then the chances of it being duplicated closely is too high imo to be realistic. If it's very, very unlikely for evolution to go "backwards" then it's also very, very unlikely for it to follow the same steps and end up with the "same" solution. Evolution has no foresight - random mutation would not result in a feature re-evolving so there must be some memory involved. That's why I suggested there was a "switch" that "turns" wings or wingless on.

If you lost the sprinkler from the end of your hose then the chances of another sprinkler occurring due to evolution would be almost impossible unless there were only a reduced number of possible options available.


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Dr Jack
Member (Idle past 182 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 20 of 49 (509758)
05-24-2009 12:01 PM
Reply to: Message 1 by doc
05-17-2009 7:08 PM


Evolution doesn't have a direction so surely it is possible for it to go backwards?

I had a thought about this. You seem to be thinking of forward, and backward as directions evolution can take. This is, of course, not true. If you want to consider an evolutionary change as having a direction, you'd need to consider it in a (very) multi-dimensional space. For example, if you had DNA coding for just this short section of protein LIAGMP, a change in a single one of those amino acids is effectively a direction evolution can take, so with just six amino acids you have six directions! But, wait, that's not right because there are 19 different possible other amino acids each one could change to.

As you can imagine the number of "directions" rapidly becomes bewilderingly high. So, in fact, "backwards" is not a choice of two options; it's a choice of billions so the chance that a new mutation will directly reverse a prior mutation is tiny*.

* - unless we're considering bacteria which have small genomes, huge population sizes and tiny generation times meaning the probability of any change occurring is very high indeed.


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Taz
Member (Idle past 1369 days)
Posts: 5069
From: Zerus
Joined: 07-18-2006


Message 21 of 49 (509764)
05-24-2009 3:48 PM
Reply to: Message 1 by doc
05-17-2009 7:08 PM


doc writes:

Evolution doesn't have a direction so surely it is possible for it to go backwards?


I see this question as nonsensical. Evolution only has 1 direction, and that is forward. Even if we eventually turn to slime in order to survive, it would still be forward evolution. If we eventually turn to single celled bacteria, it would still be forward evolution. There's no such thing as backward evolution.
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RAZD
Member
Posts: 19756
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 5.6


Message 22 of 49 (509845)
05-25-2009 12:39 PM
Reply to: Message 19 by doc
05-24-2009 11:57 AM


Hi Doc,

I'm not sure whether your example was over 50M years or 50k years as you've suggested both.

Well you could read the article and find out, but thanks for the correction:

http://news-info.wustl.edu/tips/2003/science-tech/walkingstick.html

quote:
Maxwell and his collaborators at Brigham Young University discovered that some species lost the ability to fly at one point of their evolution and then re-evolved it 50 million years later. Moreover, the data indicate it is likely that re-evolution of these species may have occurred more than once.

It's actually over a longer period of time, as the 50 million years applies to one instance.

That's why I suggested there was a "switch" that "turns" wings or wingless on.

Curiously, you are still left with evolving the ON switch and the OFF switch and the ON switch and the OFF switch ...

However if it's 50M then I'd suggest that it's very unlikely for a wing to re-evolve. When a feature is "lost" then the chances of it being duplicated closely is too high imo to be realistic. If it's very, very unlikely for evolution to go "backwards" then it's also very, very unlikely for it to follow the same steps and end up with the "same" solution.

Agreed. It is much more likely to find other steps to reach the same result. That the vein patterns in the wings are the same means that the vein pattern is not lost, ... but then this is the vein pattern in the part when it is NOT a wing as well as when it IS a wing. But the question remains: if the wing is turned OFF by one mutation, and then later is turned ON, then is this a new mutation of a new ON switch, or is this a new mutation that reverses the mutation that turns the wing OFF? It is entirely possible that both could occur.

Evolution has no foresight - random mutation would not result in a feature re-evolving so there must be some memory involved.

Selection for improved survival and reproductive success in an environment where having wings is beneficial would favor their use. Selection for improved survival and reproduction in an environment where having wings is detrimental would favor their absence.

If you lost the sprinkler from the end of your hose then the chances of another sprinkler occurring due to evolution would be almost impossible unless there were only a reduced number of possible options available.

Seeing as the analogy was not about how sprinklers evolve, this is a non-sequitur. The point is (was) that any sprinkler will assist in watering the lawn so that I don't have to stand there with my thumb on the end.

Do you want to discuss how a sprinkler could evolve? Or do you want to admit that your "almost impossible" is just your argument from incredulity, coupled with a lack of imagination?

Enjoy.


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This message is a reply to:
 Message 19 by doc, posted 05-24-2009 11:57 AM doc has responded

Replies to this message:
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Dr Adequate
Member
Posts: 16085
Joined: 07-20-2006
Member Rating: 10.0


Message 23 of 49 (509852)
05-25-2009 1:46 PM
Reply to: Message 19 by doc
05-24-2009 11:57 AM


If you lost the sprinkler from the end of your hose then the chances of another sprinkler occurring due to evolution would be almost impossible unless there were only a reduced number of possible options available.

It would be completely impossible: hoses do not reproduce with variation.


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Dr Adequate
Member
Posts: 16085
Joined: 07-20-2006
Member Rating: 10.0


Message 24 of 49 (509859)
05-25-2009 2:47 PM
Reply to: Message 21 by Taz
05-24-2009 3:48 PM


I see this question as nonsensical. Evolution only has 1 direction, and that is forward. Even if we eventually turn to slime in order to survive, it would still be forward evolution. If we eventually turn to single celled bacteria, it would still be forward evolution. There's no such thing as backward evolution.

Well, it depends on how you interpret the question. I don't think he means: "could evolution go against natural selection?"


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doc
Junior Member (Idle past 3497 days)
Posts: 11
Joined: 05-17-2009


Message 25 of 49 (509874)
05-25-2009 5:28 PM
Reply to: Message 22 by RAZD
05-25-2009 12:39 PM


RAZD writes:

That the vein patterns in the wings are the same means that the vein pattern is not lost, ... but then this is the vein pattern in the part when it is NOT a wing as well as when it IS a wing. But the question remains: if the wing is turned OFF by one mutation, and then later is turned ON, then is this a new mutation of a new ON switch, or is this a new mutation that reverses the mutation that turns the wing OFF? It is entirely possible that both could occur.

I think it's more probable that the information is not lost and hence in this case evolution can reverse something that was done millions of years ago.

You mentioned lack of imagination........well I can imagine many many ways that a problem could be addressed and if evolution is random (with selection) then I think that if a wing was "lost" then another competing feature could evolve to replace it. Using the same solutions does not imply randomness.


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Replies to this message:
 Message 28 by Blue Jay, posted 05-26-2009 1:13 PM doc has responded
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doc
Junior Member (Idle past 3497 days)
Posts: 11
Joined: 05-17-2009


Message 26 of 49 (509875)
05-25-2009 5:31 PM
Reply to: Message 24 by Dr Adequate
05-25-2009 2:47 PM


Dr Adequate writes:

TWell, it depends on how you interpret the question. I don't think he means: "could evolution go against natural selection?"

No I mean that it can reverse previous evolution as in RAZD's example. You can always argue that evolution like time does not go backwards but I meant that features could be dropped and reused. I'm not sure how far back this could go but RAZD's example implies millions of years.


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deerbreh
Member (Idle past 970 days)
Posts: 882
Joined: 06-22-2005


Message 27 of 49 (509962)
05-26-2009 12:14 PM


To answer the OP:

No. You can't "reverse" something which has no direction to start with.

On the other hand, is natural selection reversible? - that is can a gene change in frequency and then change back to the original frequency within a population? Absolutely.


  
Blue Jay
Member (Idle past 775 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 28 of 49 (509970)
05-26-2009 1:13 PM
Reply to: Message 25 by doc
05-25-2009 5:28 PM


Hi, Doc.

Doc writes:

I think it's more probable that the information is not lost and hence in this case evolution can reverse something that was done millions of years ago.

So, in your mind, what caused the trait to disappear the first time?

If no information was lost, then what made the walking-sticks' wings stop growing?


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


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doc
Junior Member (Idle past 3497 days)
Posts: 11
Joined: 05-17-2009


Message 29 of 49 (509983)
05-26-2009 2:13 PM
Reply to: Message 28 by Blue Jay
05-26-2009 1:13 PM


Bluejay writes:

So, in your mind, what caused the trait to disappear the first time?

If no information was lost, then what made the walking-sticks' wings stop growing?

I don't know. Maybe there was some breeding between two types??? However I think the traits remained in the population and if that's true then maybe evolution could regress.


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Perdition
Member (Idle past 1315 days)
Posts: 1593
From: Wisconsin
Joined: 05-15-2003


Message 30 of 49 (509991)
05-26-2009 2:48 PM
Reply to: Message 25 by doc
05-25-2009 5:28 PM


Using the same solutions does not imply randomness.

Who said it's the same solution? Just because they look similar doesn't mean they are duplicates. Evolution, and natural selection in particular, are still constrained by the laws of physics. If selection is moving towards a flying model, the ultimate "design" is going to necessarily resemble the original flying model despite having, perhaps, an entirely different set of genes creating the apparatus.


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