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Author Topic: Are sharks and crocodiles evidence of Lamarckian evolution?  (Read 19438 times)

Offline norcalclimber

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From what I have always heard, both sharks(some) and crocodiles as well as a few others have not really evolved in the past 65 million years or so.  It seems to me that all the species I have heard of which have not evolved are extremely well suited for their environment.  Does this provide evidence that evolution happens as Jean Baptiste Lamarck suggested, because it is needed, and that if no evolution is needed no evolution occurs?


 

Offline Bored chemist

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #1 on: 04/06/2010 18:29:34 »
That's not the normal meaning of Lamarkian evolution.

Some people are red headed, that's not a "needed" bit of evolution, but it happened anyway.
At best, the sharks suggest that evolution is slow in the absence of pressure to evolve.
There's also the point that there are many different sorts of sharks (and crocs), all derived from a common ancestor so the simple answer is  "No".
 

Offline norcalclimber

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #2 on: 06/06/2010 00:42:15 »
That's not the normal meaning of Lamarkian evolution.

Some people are red headed, that's not a "needed" bit of evolution, but it happened anyway.
At best, the sharks suggest that evolution is slow in the absence of pressure to evolve.
There's also the point that there are many different sorts of sharks (and crocs), all derived from a common ancestor so the simple answer is  "No".

While I know there are some sharks(and crocs) which evolved during the past 65 million years, I was under the impression that there are also some which haven't just evolved "slowly", they haven't evolved at all...not even a little.  This seems to suggest not that evolution is slow in the absence of pressure, but rather nonexistent.  Seems to me that implies that evolution is a response to an environmental stressor, and not just the amplification of random traits. 

And 65 million years is not a short period of time when it comes to evolution, since all life you see as well as millions of species which have gone extinct, didn't even really start evolving until ~750 million years ago.
« Last Edit: 06/06/2010 00:44:23 by norcalclimber »
 

Offline Bored chemist

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #3 on: 06/06/2010 10:31:14 »
How can we know exactly what the sharks were like 65M years ago?
To support your claim you would need to recover DNA from them and prove that it was exactly the same as today's sharks' DNA.
The best we can say is that evolution is slow when there's no pressure to evolve.
So what?
 

Offline echochartruse

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #4 on: 07/06/2010 01:47:23 »
norcalclimber, I know you don't understand my previous posts of the Tasmanian Devil but I believe this is exactly what you are talking about here.

The Devils have genetically altered to mature earlier and to breed eariler due to their cancer which kills them within 3-4 months after getting it. This is the first documented case and supports Jean Baptiste Lamarck. This is adaptation happening as we see it, Now..

Prior to this cancer the gene pool was as clones for the Devil.
 

Offline BenV

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #5 on: 07/06/2010 09:16:50 »
That's not the normal meaning of Lamarkian evolution.

Some people are red headed, that's not a "needed" bit of evolution, but it happened anyway.
At best, the sharks suggest that evolution is slow in the absence of pressure to evolve.
There's also the point that there are many different sorts of sharks (and crocs), all derived from a common ancestor so the simple answer is  "No".

While I know there are some sharks(and crocs) which evolved during the past 65 million years, I was under the impression that there are also some which haven't just evolved "slowly", they haven't evolved at all...not even a little.  This seems to suggest not that evolution is slow in the absence of pressure, but rather nonexistent.  Seems to me that implies that evolution is a response to an environmental stressor, and not just the amplification of random traits. 

And 65 million years is not a short period of time when it comes to evolution, since all life you see as well as millions of species which have gone extinct, didn't even really start evolving until ~750 million years ago.
This assumes no pressure on these species - there could well be a selective pressure to not change - they are well adapted to their environment and lifestyle, and deviation from those adaptations might be selected against.
 

Offline BenV

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #6 on: 07/06/2010 09:23:13 »
norcalclimber, I know you don't understand my previous posts of the Tasmanian Devil but I believe this is exactly what you are talking about here.
I'm not so sure about that...

Quote
The Devils have genetically altered to mature earlier and to breed eariler due to their cancer which kills them within 3-4 months after getting it. This is the first documented case and supports Jean Baptiste Lamarck. This is adaptation happening as we see it, Now..

Prior to this cancer the gene pool was as clones for the Devil.

Well, the disease is leading to lifestyle changes - the devils are breeding earlier as a result of the disease.  There's no need for there to have been any genetic change that leads to younger breeding - the tumour itself will change the ability of adult males to fight for mates.

This, in turn, may well lead to greater genetic variation, as more males are mating (rather than fewer, stronger males monopolising the females).  This isn't Lamarkian - that would involve passing down acquired traits, of which there is no suggestion in the tasmanian devil's case.

In this case an environmental factor (the disease) is leading to population structure changes (earlier mating) which results in a different set of genes being passed on.  Nothing out of the ordinary here. 

In many ways, (and forgive me for speculating) we're seeing something similar in human populations - an environmental factor (medicine) leads to population changes (older couples having children) which change the set of genes that goes into the next generation.
 

Offline Bored chemist

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #7 on: 07/06/2010 22:27:13 »
Most cancers are not infectious. The only reason these Devils have this problem is because they have very little genetic diversity. This in turn is because they were nearly wiped out and are now very inbred.
Their current behaviour- mating earlier- is an indirect response to an external stimulus; that stimulus is us.
Nothing to do with Lamarck.
 

Offline norcalclimber

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #8 on: 09/06/2010 17:44:51 »

This assumes no pressure on these species - there could well be a selective pressure to not change - they are well adapted to their environment and lifestyle, and deviation from those adaptations might be selected against.

Ok, that makes sense.  But it was my understanding that Lamarckian evolution basically said that evolution happens because it needs to happen, i.e. giraffes have long necks because they needed them, not by a series of totally random mutations over a few hundred million years.  Under this, it makes sense that a species which is extremely well adapted to it's environment and had no need to change, would be selected against change, which makes sense to be the case here. 

So what am I missing about the situation/science that makes me still feel like it fits a little better with Lamarckian evolution vs Darwinian evolution?
 

Offline rosy

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #9 on: 09/06/2010 18:33:20 »
Lamarkian evolution said that an giraffe would stretch its neck during its lifetime and thus its neck would become longer.. the newly lengthened neck would then be passed on to its offspring.

It is like saying that if I have a hand chopped off, and then have a child, the child is likely to be born with no hand.

In the light of modern knowledge, it sounds pretty daft. But Lamark didn't know about chromosomes, let alone genes (tho' he might have been expected to know at least in principle about industrial accidents and amputations).
 

Offline norcalclimber

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #10 on: 09/06/2010 18:49:42 »
Lamarkian evolution said that an giraffe would stretch its neck during its lifetime and thus its neck would become longer.. the newly lengthened neck would then be passed on to its offspring.

It is like saying that if I have a hand chopped off, and then have a child, the child is likely to be born with no hand.

In the light of modern knowledge, it sounds pretty daft. But Lamark didn't know about chromosomes, let alone genes (tho' he might have been expected to know at least in principle about industrial accidents and amputations).


ahhhh, ok, thank you for the clarification.
 

Offline Bored chemist

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #11 on: 09/06/2010 19:13:37 »
It may seem odd to consider this idea "It is like saying that if I have a hand chopped off, and then have a child, the child is likely to be born with no hand." but, if Lamarckian evolution worked, Jewish boys would be born with no foreskin.
 

Offline norcalclimber

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #12 on: 09/06/2010 19:17:22 »
It may seem odd to consider this idea "It is like saying that if I have a hand chopped off, and then have a child, the child is likely to be born with no hand." but, if Lamarckian evolution worked, Jewish boys would be born with no foreskin.

Lol, point taken :)
 

Offline echochartruse

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #13 on: 13/06/2010 23:53:34 »
It may seem odd to consider this idea "It is like saying that if I have a hand chopped off, and then have a child, the child is likely to be born with no hand." but, if Lamarckian evolution worked, Jewish boys would be born with no foreskin.
Would that be similar to the French Bulldog and the Pembroke Welsh Corgi which are born with docked tails?
 

Offline Bored chemist

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #14 on: 14/06/2010 19:37:44 »
It may seem odd to consider this idea "It is like saying that if I have a hand chopped off, and then have a child, the child is likely to be born with no hand." but, if Lamarckian evolution worked, Jewish boys would be born with no foreskin.
Would that be similar to the French Bulldog and the Pembroke Welsh Corgi which are born with docked tails?

No, not really.
 

Offline Geezer

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #15 on: 15/06/2010 01:10:06 »
Would that be similar to the French Bulldog and the Pembroke Welsh Corgi which are born with docked tails?

The Cardigan Welsh Corgi is born with a long tail, but without a cardigan.
 

Offline imatfaal

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #16 on: 15/06/2010 12:18:10 »
Would that be similar to the French Bulldog and the Pembroke Welsh Corgi which are born with docked tails?

Quote
Tail
Historically, the Pembroke was a breed with a natural bob tail (very short tail). Due to the advent of docking, the trait was not aggressively pursued, with breeders focusing instead on other characteristics and artificially shortening the tail when necessary. Given that some countries are now banning docking, breeders are again attempting to select for dogs with the genes for natural bob tails.
http://en.wikipedia.org/wiki/Pembroke_Welsh_Corgi

they are born with short (not docked) tails - and it seems that more recently they are selectively bred for short(er) tails.  dogs are an unusual case as they are almost entirely selectively bred - we have been choosing (either consciously or unconsciously) for desired traits over many thousands of generations. if you docked a labrador's tail (you should be locked up for starters), the progeny of this dog would not have a noticeably shorter tail.  even if you did this over many generations you would merely select for dogs that were best able to cope with the procedure and whose ability to breed was unaffected - you would not, necessarily, end up with dogs with shorter tails.

lamarck is making a bit of a comeback recently - epigenetics has opened the possibility that not everything that is passable to next generation is received from previous generation (plus random mutation).  together with an appraisal of what lamarck actually said, and a realisation that he shouldnt be bracketed with Lysenko, this has lead to a bit a of a re-reading for Lamarck 

However, what is generally considered to be lamarckism - the inheritability of traits acquired over a single generation - is still not accepted.

 

Offline echochartruse

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #17 on: 16/06/2010 02:28:28 »
please read...http://jhered.oxfordjournals.org/cgi/reprint/100/2/236.pdf

C189G gene mutation accommodates the breeding of dogs that require tail docking for showing.
Now tail docking is outlawed.
The dogs with the C189G gene are bred more often for the desired effect for showing.

There are over 17 different dog breeds that carry this short tail gene.

I'm wondering if there has ever been a study done involving Jewish male children who have had their forskin removed to find out whether the forskin is shorter at birth now because of it!
« Last Edit: 16/06/2010 02:36:27 by echochartruse »
 

Offline echochartruse

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #18 on: 16/06/2010 02:45:52 »
However, what is generally considered to be lamarckism - the inheritability of traits acquired over a single generation - is still not accepted.

Excepting wealth, there are other inherited traits we can not deny are passed down in a single generation. That's what makes us who we are. I look like my parents. half of my genes from dad the other half from mum.
Unfortunately gene mutations causes disease which can be also be inherited directly by the next generation.
If both dogs had their tail docked might they both have a gene mutation that caused their offspring to have a short tail? Are you suggesting that t only happens over vast periods of time?
Think about breast cancer, Alzheimer's and many more gene mutations are inherited by the next generation.
« Last Edit: 16/06/2010 03:43:35 by echochartruse »
 

Offline Geezer

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #19 on: 16/06/2010 05:58:16 »

If both dogs had their tail docked might they both have a gene mutation that caused their offspring to have a short tail?


Er well, no.

Dog breeders select a random characteristic of an individual (like, for example, a short tail) and reinforce the desired genetic characteristic by practices that we might consider incestuous in humans. This accelerates the genetic alteration to produce a particular breed in a relatively short time. Unfortunately, the consequent reduction in genetic diversity also reinforces certain undesirable genetic traits, like predispositions to certain abnormalities and susceptibility to particular diseases.
 

Offline echochartruse

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #20 on: 16/06/2010 11:02:54 »
Ancient Shepard's and herders docked their dog's tails to avoid paying taxes for them. To identify them as working dogs. the first records of naturally occuring bobtails that I have found shows that in the 1800's the taxes were abolished but people continued to dock tails for the show standards. It wasn't until 1800's that the first natural bobtail dog was recored an English sheep dog. The Pembroke Corgi was docked to distinguish it from a fox. The Pembroke corgi was also used for herding as far back as the 10th century.

Correct by selecting for specific visual characteristics to breed for conformity such as for short tail the Pembroke Corgi and the French Bulldog which are 2 dogs that usually have their tail docked if long, have developed a genetic mutation which can be inherited by their off spring. This is the C189G gene found in 17 -23 dog breeds. These 17-23 dog breeds are usually shown with docked tails to comply with the standards of the associations. But since this is now illegal  to dock the tails the odd one or two dogs that are being born with this genetic mutation is being bred to satisfy the dog show standards. (This genetic mutation can also be lethal or cause small litters.)

This genetic mutation did happen, when can not be confirmed, somewhere in the 1800's I imagine due to records of natural bobtail dogs.

I would suggest this mutation came about due to docking dog's tails. All dogs that have natural bobtail genes are herding dogs.

 

Offline imatfaal

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #21 on: 16/06/2010 11:18:42 »
please read...http://jhered.oxfordjournals.org/cgi/reprint/100/2/236.pdf

C189G gene mutation accommodates the breeding of dogs that require tail docking for showing.
Now tail docking is outlawed.
The dogs with the C189G gene are bred more often for the desired effect for showing.
There are over 17 different dog breeds that carry this short tail gene.


To precis - there is possibly a ancestral (naturally occurring) mutation to a part of the dog genome that causes short tails.  this trait is now regularly selected by human intervention.  Corgis do not have the short tail because we would cut it off otherwise - they have short tail because we decide which dog breeds with which bitch.  

Dogs exist because we humans are good at selecting breeding pairs that have a greater chance of reproducing preferred traits.  there is no evidence of the genetic sequence being adapted within a single generation and thus allowing the inheritability of an acquired trait.

Excepting wealth, there are other inherited traits we can not deny are passed down in a single generation. That's what makes us who we are. I look like my parents. half of my genes from dad the other half from mum.
 - please note difference between acquired trait and inherited trait

All the genetic characteristics that make echochartruse look like echochartruse were inherited from your parents through a combination of your mothers and fathers genes.  if your father had lost a leg in an accident this would not be inherited.  every single one of the genes (barring genetic damage/random mutation) that you pass onto your children will have come from your parents.  no matter what traits you gain during your lifetime or changes to your bodily appearance - the genes you pass to your offspring will be those you received from your parents (again barring genetic damage/random mutation).
 

Offline imatfaal

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #22 on: 16/06/2010 11:47:06 »
I would suggest this mutation came about due to docking dog's tails.

This is Larmarckism - and there is no evidence to back it up.  The article you quoted does NOT substantiate this claim in any way.  Do you seriously believe; that given identical twins one of whom has lost a limb after an accident that the children of the 'amputee twin' will have different genetic inheritance than those of the 'non-amputee twin'?   

Matthew
 

Offline echochartruse

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #23 on: 17/06/2010 09:42:36 »
To precis - there is possibly a ancestral (naturally occurring) mutation to a part of the dog genome that causes short tails. 

......... there possibly might be..... or there might not.
I am unable to find evidence of either, all I know is that shepherd dogs were tail docked for centuries and shepard dogs were the first dogs found to inherit the gene mutation.

...this trait is now regularly selected by human intervention. 
Corgis do not have the short tail because we would cut it off otherwise - they have short tail because we decide which dog breeds with which bitch.

Not forgetting that this gene only appeared around 1800ís and yes human intervention has influenced it in one or more ways.
Should 2 dogs carry this gene it is fatal to the off spring. Pups only survive if one parent only carries the gene.

Dogs exist because we humans are good at selecting breeding pairs that have a greater chance of reproducing preferred traits.  there is no evidence of the genetic sequence being adapted within a single generation and thus allowing the inheritability of an acquired trait.


Dogs would survive and they do without human intervention also, but wild dogs do not have the bobtail gene.

 
  - please note difference between acquired trait and inherited trait
All the genetic characteristics that make echochartruse look like echochartruse were inherited from your parents through a combination of your mothers and fathers genes.  if your father had lost a leg in an accident this would not be inherited.  every single one of the genes (barring genetic damage/random mutation) that you pass onto your children will have come from your parents.
No matter what traits you gain during your lifetime or changes to your bodily appearance - the genes you pass to your offspring will be those you received from your parents (again barring genetic damage/random mutation).

OK I understand

Why should we bar genetic damage /random mutation if you think this is the pathway to evolution,.. you obviously donít. Is this correct?

This is Larmarckism - and there is no evidence to back it up.  The article you quoted does NOT substantiate this claim in any way.  Do you seriously believe; that given identical twins one of whom has lost a limb after an accident that the children of the 'amputee twin' will have different genetic inheritance than those of the 'non-amputee twin'?   
Matthew

If Identical twins married identical twins would each set of twins have identical children? Somehow I donít think so, There are life factors associated that influences individual life.

Quote from: http://www.sciencedaily.com/releases/2009/01/090118200632.htm

Rethinking The Genetic Theory Of Inheritance: Heritability May Not Be Limited To DNA
 The CAMH study showed that epigenetic factors Ė acting independently from DNA Ė were more similar in monozygotic twins than dizygotic twins. This finding suggests that there is a secondary molecular mechanism of heredity. The epigenetic heritability may help explain currently unclear issues in human disease, such as the presence of a disease in only one monozygotic twin, the different susceptibility of males (e.g. to autism) and females (e.g. to lupus), significant fluctuations in the course of a disease (e.g. bipolar disorder, inflammatory bowel disease, multiple sclerosis), among numerous others.

It would be interesting for someone to study the length of foreskin in various groupís babies that practice  circumcision and compare those who donít. It would be very interesting for someone to research when exactly the Bobtail gene appeared and its history. To reseach why only shepard type dogs and dogs that were tail docked are more likely to have this gene.

The bobtail gene did not always exist and does not exist in some dog breeds at all. But I would be unwise to disregard that the preference in dog shows of the natural bobtail did not influence this genetic mutation.

Please read....... Epigenetics: DNA Isnít Everything http://www.sciencedaily.com/releases/2009/04/090412081315.htm

Cell memory may be important here, what if a generation or two of dogs were tail docked and bred, the ones who didnít get docked were sold as pets not breeders, the un docked tail dogs never bred, isnít there a slight chance that cell memory played an important roll in this genetic mutation? That it only took one dog's genes to mutated to accommodated the bobtail which was then passed onto the next generation?

We just can't block our minds because we dont have the evidence, we should find the evidence for or against. Can anyone find evidence against this type of evolution?


« Last Edit: 17/06/2010 09:52:11 by echochartruse »
 

Offline echochartruse

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Are sharks and crocodiles evidence of Lamarckian evolution?
« Reply #24 on: 17/06/2010 10:12:14 »
Epigenetic traits are aquired and can be inherited by the next generation.
 

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Are sharks and crocodiles evidence of Lamarckian evolution?
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