What is the Mechanism of Natural Selection for Evolution?

[Grumpy]

matthew809

Frug females like to build nests in the rocks(where they wait for the male frugs), some of them build their nests among the slippery rocks of waterfalls, their predators can't reach them there.So for centuries the frug females have been selected to nest among the slippery rocks. The frug male with slick skin can't reach those females very well, they slip off the rocks into the stream and have to climb the hill again, if they survive the fall. Our frug has a rough patch of skin on it's belly that gives him some traction on the rocks and he can easily reach the females. Soon all frugs will have a rough patch on their belly. It's just that simple.

Whether the rough patch helps him in his life(compared to other frugs)or not is irrelevant if it allows him an advantage in reproduction.

Grumpy

 

[Billy T]

I admit that does seem like a partly plausible scenario. But, isn't it more than likely that the frug would be totally unaware of this possible benefit ...

No that is unimaginable - Not even normal humans know much at birth - you learn to use to your advantage what you have got.
It is not a question of intelligence, but of trial and error experience. Normal soft belly frugs don't know not to slide over rough rocks - they learn that the hard way. The hard belly frug did not know frugs can't slide over rough rocks and so he did and used this ability to his advantage all his life.

For example:

Marfan syndrome (also called Marfan's syndrome) is a genetic disorder caused by the misfolding of the protein fibrillin-1. Fibrillin-1 is coded by the gene FBN1 [1][2]

People with Marfan tend to be unusually tall, with long limbs and long, thin fingers. Marfan syndrome is an autosomal dominant disorder, meaning that people who inherit only one copy of the Marfan FBN1 gene from either parent will develop Marfan syndrome and be able to transmit it to their children.

It is widely suspected that Abraham Lincoln had mild Marfan disease - He and others with that genetic defect learned they could do things with their fingers that others could not do - were "double jointed." Some exceptionally gifted piano players may have Marfan disease - but it is a disease as it cuts you life expectance - causes heart problems etc.

 

[matthew809]

matthew809

Frug females like to build nests in the rocks(where they wait for the male frugs), some of them build their nests among the slippery rocks of waterfalls, their predators can't reach them there.So for centuries the frug females have been selected to nest among the slippery rocks. The frug male with slick skin can't reach those females very well, they slip off the rocks into the stream and have to climb the hill again, if they survive the fall. Our frug has a rough patch of skin on it's belly that gives him some traction on the rocks and he can easily reach the females. Soon all frugs will have a rough patch on their belly. It's just that simple.

Grumpy

I said it was a hard patch not a rough one. If anything the hard patch would be denser and weigh the frug down more.

But it's still a good response and your point is very valid. I will ponder it tonight in bed...

 

[Billy T]

The dice have to be loaded with enough imbalance to actually make a difference though. It is possible that the imbalance could be so miniscule that it wouldn't have any effect on the roll of the dice no matter how many times you throw them.

You are stating inconsistent non-sense. If it makes no advantage, not even a small one, then the dice are not "loaded." Again you, not me, said the hard belly spot WAS an advantage.

 

[Write4U]

How does a minor biological variance(yet theoretically advantageous one) come to dominate the gene pool... over and over and over again.... millions of times.... to create what we see today?
Besides the relatively sparse dramatic environmental change, what fundamental mechanism can explain such consistent "natural selection" for the evolution of life?

For example, lets imagine some weird frog-like creature on some hypothetical earth-like planet, billions of years ago. There's millions of these frugs on this planet, and hundreds of other equally weird, young species. One of these frugs has a spot of harder flesh on it's underbelly. It is unique, and will be the basis for a new body part of a new species, billions of years in the future.

But let's not worry about the far future of these frugs just yet. For now, how does this minor biological variance (yet theoretically advantageous one) initially come to dominate the gene pool?

Because survival and mating ensures the passing on of beneficial genes. Non-survival prevents breeding and passing on of the non beneficial genes. The selection is not ordered or designed. Survival (by any means) and breeding is the single requirement in the mehanism of biological evolution.

The variety is a result of many causes which impact the genetic code. The truth is that males only exist to introduce variety in a species. For procreation they have no other function. This is why bee drones are kicked out of the hive after the mating flight. They are useless except for breeding purposes.

 

[billvon]

How does a minor biological variance(yet theoretically advantageous one) come to dominate the gene pool... over and over and over again.... millions of times.... to create what we see today?

Because traits that are even slightly advantageous lead to a very slight statistical preference for those genes being expressed in the next generation. Multiply that by millions of reproductive cycles, and if you gain even .01% penetration in each generation, it soon dominates.

Besides the relatively sparse dramatic environmental change, what fundamental mechanism can explain such consistent "natural selection" for the evolution of life?

Better survival, and thus more reproduction, of the organisms with better survival traits.

For example, lets imagine some weird frog-like creature on some hypothetical earth-like planet, billions of years ago. There's millions of these frugs on this planet, and hundreds of other equally weird, young species. One of these frugs has a spot of harder flesh on it's underbelly. It is unique, and will be the basis for a new body part of a new species, billions of years in the future.
But let's not worry about the far future of these frugs just yet. For now, how does this minor biological variance (yet theoretically advantageous one) initially come to dominate the gene pool?

If it confers no advantage - it does not.
If it helps even a tiny percentage of frogs avoid being skewered by crabs from beneath, it will be amplified and passed on, and will eventually dominate.

 

[wellwisher]

If it confers no advantage - it does not.
If it helps even a tiny percentage of frogs avoid being skewered by crabs from beneath, it will be amplified and passed on, and will eventually dominate.

What this presumes is all mutations are done at conception. Say after conception, as cells divide and the critter grows, there are also mutations in the DNA occurring within some of these dividing cells. The human body has 25 trillion cells, as one estimate. There is room for more mutations. To make it clear I will differentiate reproductive mutations as being different from growth mutations.

The earlier these growth mutations, the more dominate they can become with respect to final body systems. When the critter matures and then becomes part of the reproductive cycle, what is passed on terms of the DNA? Do growth mutations play a role, since they can play a role in selection.

For example, say one of these developmental mutations, due to growth mutations, gives him an advantage and he wins reproductive rights, does this developmental change pass forward? If not, could the next generation actually could go backwards, since he won based on a non transferable mutation? For example, the growth mutation gives him stronger legs for jumping, but this is not passed forward since it is isolated to the legs and was not part of the original DNA. This cheats the system causing the wrong frog to move forward at the level of the base DNA.

This is a valid question since if we took one bacteria and allowed it to divide into 20 trillion cells, we would get mutations. We would say those which have selection would survive better. In the above, the ecosystem of all the cells of the body have their own selection process within the organisms itself. How does internal selection due to growth mutations, become projected into the DNA of the gamete cells or does it?

 

[origin]

What this presumes is all mutations are done at conception. Say after conception, as cells divide and the critter grows, there are also mutations in the DNA occurring within some of these dividing cells. The human body has 25 trillion cells, as one estimate. There is room for more mutations. To make it clear I will differentiate reproductive mutations as being different from growth mutations.

The earlier these growth mutations, the more dominate they can become with respect to final body systems. When the critter matures and then becomes part of the reproductive cycle, what is passed on terms of the DNA? Do growth mutations play a role, since they can play a role in selection.

For example, say one of these developmental mutations, due to growth mutations, gives him an advantage and he wins reproductive rights, does this developmental change pass forward? If not, could the next generation actually could go backwards, since he won based on a non transferable mutation? For example, the growth mutation gives him stronger legs for jumping, but this is not passed forward since it is isolated to the legs and was not part of the original DNA. This cheats the system causing the wrong frog to move forward at the level of the base DNA.

This is a valid question since if we took one bacteria and allowed it to divide into 20 trillion cells, we would get mutations. We would say those which have selection would survive better. In the above, the ecosystem of all the cells of the body have their own selection process within the organisms itself. How does internal selection due to growth mutations, become projected into the DNA of the gamete cells or does it?

It is fun to try to get into the mechanism of evolution, which is the theory part, but none of that has any bearing on the fact of evolution.

 

[Billy T]

It is fun to try to get into the mechanism of evolution, which is the theory part, but none of that has any bearing on the fact of evolution.

I agree, but don't think Wellwisher even has a point. Lets use his mutation in a leg muscle cell, that by hypotheses makes that cell pull a little harder. It is only one cell which may become about 10 if the mutation occurs when the total leg mass is 10% of the adult's leg mass and will only very slightly help that individual jump etc. while he lives. It has no relationship to the genes he may pass on to the next generation. They may be better or worse, than the average, for the gene pool's long term survival.

Wellwisher has a false "Lamarckian" view of genetics. I.e. the better jumping could equally well be obtain by weekly visits to the gym, but that too would not change, for better or worse, the genes he gives to the next generation.

 

[origin]

I agree, but don't think Wellwisher even has a point.

Agreed.

 

[wellwisher]

Wellwisher has a false "Lamarckian" view of genetics. I.e. the better jumping could equally well be obtain by weekly visits to the gym, but that too would not change, for better or worse, the genes he gives to the next generation.

This is the whole point. There are many scenarios, where a selective advantage will not pass forward genetically. I used the example of growth based mutations. Another that is mentioned, is one frog went to the gym, but genetically he was less fit to begin with. He may win breeding rights but the best genes don't go forward since the gym will not transfer genetically.

If his baby frogs don't go to the gym the species may not survive with genetics alone, since it selected a non-genetic wild card. This also brings up the brain and consciousness, which is important to life, which can learn tricks to win, which may not be part of the DNA. This smart critter, may breed but the genetic alone may not have the selective advantage without the gimmick. Or the gimmick weighs more than the genetic aspects causing species decline.

If you look at the decline in America culture is is due to noncoding selection having too much weight. We don't compete but have quotas, which do not reflect the genetics but more of the noncoding. The decline of empires is less due to poor genetics as other factors.

 

[Billy T]

This is the whole point. There are many scenarios, where a selective advantage will not pass forward genetically. I used the example of growth based mutations. Another that is mentioned, is one frog went to the gym, but genetically he was less fit to begin with. He may win breeding rights but the best genes don't go forward since the gym will not transfer genetically.

If his baby frogs don't go to the gym the species may not survive with genetics alone, since it selected a non-genetic wild card. This also brings up the brain and consciousness, which is important to life, which can learn tricks to win, which may not be part of the DNA. This smart critter, may breed but the genetic alone may not have the selective advantage without the gimmick. Or the gimmick weighs more than the genetic aspects causing species decline.

If you look at the decline in America culture is is due to noncoding selection having too much weight. We don't compete but have quotas, which do not reflect the genetics but more of the noncoding. The decline of empires is less due to poor genetics as other factors.

None of that matters as what genes go forward is NOT correlated with genetic changes in anything but the sperm and egg cells genes. There changes can increase (or decrease) their representation in the next generations.

 

[billvon]

What this presumes is all mutations are done at conception. Say after conception, as cells divide and the critter grows, there are also mutations in the DNA occurring within some of these dividing cells.

These are not passed on and are thus not part of the evolutionary process.

For example, say one of these developmental mutations, due to growth mutations, gives him an advantage and he wins reproductive rights, does this developmental change pass forward?

No.

How does internal selection due to growth mutations, become projected into the DNA of the gamete cells or does it?

It does not. Only heritable mutations can be passed on.

Another that is mentioned, is one frog went to the gym, but genetically he was less fit to begin with.

I'll give you an even simpler example. A frog with an excellent mutation is hatched and is immediately eaten by a bird. Lots of things interfere with evolution. That's one of the reason it takes millions of years, because there's a lot of noise in the system.

If you look at the decline in America culture is is due to noncoding selection having too much weight.

Given that women vote, we don't own slaves any more, blacks can now marry whites and gays are not arrested on sight - I think all those people would disagree that culture in America is declining. (Which, BTW, has nothing to do with evolution.)

 

[Write4U]

Given that women vote, we don't own slaves any more, blacks can now marry whites and gays are not arrested on sight - I think all those people would disagree that culture in America is declining. (Which, BTW, has nothing to do with evolution.)

It might still merit the term evolution but that would be social evolution, not biological evolution.

 

[Grumpy]

wellwisher

What this presumes is all mutations are done at conception. Say after conception, as cells divide and the critter grows, there are also mutations in the DNA occurring within some of these dividing cells.

It's not presumed, only mutations in the sexual gametes get passed to the next generation as that is the only DNA the child gets from the parents. All evolutionary changes occur ONLY within those sexual gametes and they are tested by that child's reproductive success. Mutations in other cells are often the cause of cancer, disease, growths or defects. None of those are passed to the next generation nor are any acquired traits picked up during an organism's lifetime.

Grumpy

 

[Forceman]

When one dreams you pass on more lives. These lives are experienced until death and then you return to the source with the silver chord and you see all of life. Evolution is within the brain and within the genes and therefore evolution occurs among all species.

 

[origin]

When one dreams you pass on more lives.

Did Mom and Dad neglect to tell you about the birds and the bees? This is not how reproduction occurs. A wet dream does not mean someone got pregnant.