Question on the Genetic Mutation part of Evolution

[Slayer]

Hi,

 

Correct me if I'm wrong, I'm new to this.

 

Genetic mutation happens randomly, and natural selection decides the direction, i.e, lets the advantageous continue their lineage.

 

I'm not comfortable with the genetic mutation part. It seems to me that mutation it is too coincidental that forming new traits isn't really possible. Don't you think there should be a system like adaptive-mutation [which is generally not accepted, right ?], or some other system that reduces the impossibility [to me at least] of mutating new traits .

 

To give an example, say we are in the period where underwater creatures started to develop fins. How does this happen ? Through genetic mutation, one of the new babies, named X, have weird area on his skin [where the fin will start growing after generations], the root of the fin ?

 

X's all babies have the same area looking weird on their skin, but one of them mutated even more, and development of fin took one step more. And it kept going like this until they formed the complete fin [by complete, i mean today's fin]. But how exactly does this work ?

 

-Do all the Xs keep having a mutation on the same spot randomly for generation after generation ?

 

-Does the mutation on the left and right side of X happen at the same time so X grows fins on both sides ?

 

-Doesn't the mutated baby have less chance of breeding because he looks different, doesn't he get isolated? I know he will have more chance to survive predators, but still, say too many of his kind survived. Wouldn't the females choose others instead of choosing X, because he looks weird, therefore stopping the advantageous trait continuing ?

 

Thats all for now, I'll keep asking when I have more questions .

 

Thanks in advance for the answers.

[Sisyphus]

Hi,

 

Correct me if I'm wrong, I'm new to this.

 

Genetic mutation happens randomly, and natural selection decides the direction, i.e, lets the advantageous continue their lineage.

 

Basically, yes.

 

To give an example, say we are in the period where underwater creatures started to develop fins. How does this happen ? Through genetic mutation, one of the new babies, named X, have weird area on his skin [where the fin will start growing after generations], the root of the fin ?

 

X's all babies have the same area looking weird on their skin, but one of them mutated even more, and development of fin took one step more. And it kept going like this until they formed the complete fin [by complete, i mean today's fin]. But how exactly does this work ?

 

It could happen that way, but it generally doesn't. It happens much more often that existing features gradually morph than entirely new features spring out of nowhere. Skeletally, a whale still has four "limbs" and a tail, still has a spine, lungs, a digestive tract more or less like ours. Is that the best possible configuration for living in the ocean? No, not by a long shot, but it's what they have, because any features they have had to develop gradually from what their ancestors already had.

 

-Do all the Xs keep having a mutation on the same spot randomly for generation after generation ?

 

No, not all. Some. And not the same mutation (a mutation that's passed on is no longer a mutation, it's just your genes). Remember that any given visible trait is likely the result of the subtle interactions of thousands of different genes, not just one "on or off" switch. Some of those genes will mutate, and if that mutation is positive, it'll be more likely to be passed on.

 

-Does the mutation on the left and right side of X happen at the same time so X grows fins on both sides ?

 

Seeing as how that's completely hypothetical, that can't really be answered, but I would imagine the same genes would affect the right and left sides of X equally.

 

-Doesn't the mutated baby have less chance of breeding because he looks different, doesn't he get isolated? I know he will have more chance to survive predators, but still, say too many of his kind survived. Wouldn't the females choose others instead of choosing X, because he looks weird, therefore stopping the advantageous trait continuing ?

 

Yes, that happens all the time, and it's called sexual selection. The traits that make a member of the opposite sex more likely to mate with you are almost as important as the traits that help you survive. Sometimes the two factors work against one another. Just look at male birds with colorful plumage. It proves to the females that they are healthy and desirable mates, but it also makes them easier prey.

 

In your example, though, that probably wouldn't happen. If I suddenly sprouted fully formed fins, I might have trouble finding a date, but if I'm just naturally a slightly better swimmer due to a slightly different body shape, it probably wouldn't matter. Or it might matter, but if it matters less than the increased likelihood that I'll even be alive for the female to consider me, then it's still a positive trait, evolution-wise.

[jackson33]

A good example for *appearance* and accepting, might be the African Elephant, which has given us a recent example...

 

Up until the 1930-40's tusk less male AE, made up less than 1% of the total. They were possibly on the verge of extinction. Poaching for the tusk killed off many, making the tusk less more appealing to the female. Today or at least recently these tusk less males made up from 35-50% of the total. (depending on source). If poaching had continued its likely the once near extinct tusk less would have prevailed and those with tusk become extinct...This by the way a very short time period.

[Slayer]

Thanks for the answers. I'll continue with this point:

 

It could happen that way, but it generally doesn't. It happens much more often that existing features gradually morph than entirely new features spring out of nowhere. Skeletally, a whale still has four "limbs" and a tail, still has a spine, lungs, a digestive tract more or less like ours. Is that the best possible configuration for living in the ocean? No, not by a long shot, but it's what they have, because any features they have had to develop gradually from what their ancestors already had.

 

I didnt really get this part.

 

Imagine a sea-creature that has no fins at all, just a straight skin. He breeds 4 babies, due to mutation, one of the babies had a "bump" on his skin, and this bump is the root of the fin [which will evolve through his lineage, but for now, this creature has only a little bump].

 

This creature with the bump breeds 5 babies, 2 have no bumps at all, 2 have the same bump as their mother. The last baby has a steeper bump, exactly on the same spot where the original bump started, but its just longer.

 

And again he breeds, bump gets longer and longer through the new babies, after a long time, we get to today's fins.

 

Isn't that really low possibility ? That the new babies keeps getting advantageous mutation, always on where the original bump was, and keeps developing the bump,through generations, into a fin. Because as far as I know, most mutations are harmful ?

[Sisyphus]

Right, that is a low possibility, because it doesn't happen that way. We don't just randomly sprout bumps. We do, however, have arms. Some of us have arms that make us slightly better swimmers. If our environment changed such that swimming well became very important to survival, those people would have a slightly better chance of surviving to produce offspring.

 

But what makes an arm better or worse? Thousands and thousands of different genes, all working together. Some of those genes will mutate. Most of those mutations will be neutral. Some will be harmful. Even less will be beneficial, but in all those thousands, eventually, there will be some. Most likely you won't notice its effect in one generation (no magical bump!). But that new set of genes is a new starting point, from which new mutations can be neutral, harmful, or beneficial. If (using your example, for argument's sake), you have a race with stubby little fin-like things, what would be a beneficial mutation? Whatever makes them more fin-like. So it's not just a coincidence that those particular mutations are passed on, it's selected for, and not unlikely in the least.

[ydoaPs]

Because as far as I know, most mutations are harmful ?

 

Most mutations are benign. IIRC, the mutation rate for humans is somewhere in the ballpark of 20 mutations/generation.

 

Watch Chapter 6 of this. Actually, I recommend watching the entire thing.

[vampares]

Most mutations are benign.

 

I would agree with this but also I think this is a complicated subject.

 

Throughout the course of ones life cells divide and die and DNA is passed along. That DNA should remain the same throughout ones life. Any number of small changes can occur. Some defective DNA will degrade and produce a spiraling myriad of disease.

 

Generation to generation you only pass half your DNA on to your offspring. What this means is that "mutation" is a collective occurrence. Seems like it take a lifetime. But the "natural selection process" starts at home.

 

SNP or single nucleotide mutations are rather benign. The most important DNA tends to be stored more safely than the extraneous DNA. A lot of DNA, especially that which deals with its own maintenance was (theoretically) evolved way back in single celled organisms whose lives really were especially suited for this type of evolution. We would not expect humankind to evolve one of these highly specialize and ever critical functions any further.

 

Ever since the Repeat Expansion epidemic came out (the Evil Seed or Jew's blood) there has been a struggle to get a clamp down on normalcy.

 

This is one mutation creating every know mutation simply by virtue of poor DNA maintenance. These mutation are NOT benign. They may expand and result in a complete chromosome breakage generations down the line. They destabilize the chromosome by setting it out of alignment. This leads to premature aging. Very bad. Very widespread. And there is no cure other than sterilization at this point. This is critical because multiple mutations can be distributed out to many different individuals. This is what is being done in Africa right now.

 

See http://www.ncbi.nlm.nih.gov/. This is the database of every mutation that ever arose out of the North African mutator. It is something like AIDS.

[CDarwin]

But the numerical majority of mutations are still benign.

[Luminal]

Right, that is a low possibility, because it doesn't happen that way. We don't just randomly sprout bumps. We do, however, have arms. Some of us have arms that make us slightly better swimmers. If our environment changed such that swimming well became very important to survival, those people would have a slightly better chance of surviving to produce offspring.

 

But what makes an arm better or worse? Thousands and thousands of different genes, all working together. Some of those genes will mutate. Most of those mutations will be neutral. Some will be harmful. Even less will be beneficial, but in all those thousands, eventually, there will be some. Most likely you won't notice its effect in one generation (no magical bump!). But that new set of genes is a new starting point, from which new mutations can be neutral, harmful, or beneficial. If (using your example, for argument's sake), you have a race with stubby little fin-like things, what would be a beneficial mutation? Whatever makes them more fin-like. So it's not just a coincidence that those particular mutations are passed on, it's selected for, and not unlikely in the least.

 

I believe he's asking how entirely new parts arise, without a simpler part.

 

Considering our ancestors transitioned from microbes to complex fish, this had to have happened a number of times, including, as in his example, the evolution of fins. Wikipedia says the fossil record for the evolution of fish is not very clear, so I could not link you to a particular species.

 

The point being (which I'm interested in myself), is how microscopic species repeatedly gained entire new systems and parts from no existing mold, a process that turned them into macroscopic creatures with dozens of systems.

 

Perhaps DNA wasn't as stable at that stage as it is today, such as in viruses today, due to the lack of a process that checks for errors in the DNA? This would cause a higher rate of mutation and a rapid evolution of complexity.

[vampares]

I suppose anything is possible.

 

If mutations are to frequent, there won't be a window of opportunity for the changes to be scrutinized and then incorporated into the population.

 

It can be argued that in a spider ball of eggs there are, say, 1000 offspring. Of those 1000 there needs to be only 1 breeding pair to maintain the population. If there are 2 than the population experiences a vertical pattern. As the world is not full of spiders, we can assume there is an equilibrium being maintained. We further make the assumption that this equilibrium maintenance is filling the role of "natural selector".

 

Anyways, there can be a greater genetic drift in a species that has 1000 offspring. If 500 are a little f'd up and 100 are really f'd up that is O.K. It is sloppy and it turns out that's not what happens -- although mass producing animals do tend to experience more genetic "instability". "Instability" does rise in domesticated environments. This is more due to the laxing of the ordinary breeding pressure allowing the population to settle in at the lower standard.

 

A human has 46 chromosomes. Other primates have other numbers. The addition/subtraction of chromosomes and cross-species-breeding does yield viable offspring in primates and other mammalian species. In humans however any substantial chromosome remove is deleterious. The condition of have an additional redundant chromosome is also harmful, and often not viable much less capable of reproduction. Exactly what biological mechanism redundant-but-not-identical-chromosomes ?

 

It seems as though this would be easier if coding DNA and structural DNA were somehow separated. And they are, and this separation is on the chromosome itself. I don't know that the structure portions don't refer to coding on other chromosomes.

 

The X chromosome seems to be a very important, highly utilized chromosome. Many structural traits have been identified as residing on this chromosome, partly because of the unique way in which it is inherited. This unique inheritance also has the potential to stave off the polarity of sexual reproduction. So this unique virtual-mono-chromatin has a purpose and still undergoes genetic recombination. Defects on this chromatin are exaggerated in males. When there are two copy of a gene, one is defective, a defective protein will be made half the time. This allows for survival in sort of a "safe mode". Any sibling who has no defect is more likely to thrive -- evolution depends on this. It is highly unlikely the Y-chromosome does much of anything but sit next to X. I don't think another vestigial chromatin will find it's way into the genome.

 

But still the question may not be "where is my John Wayne?" but "where is Dr. Cornelius and the Ferengi?" as cross-"species" breeding may be the only way to add material to the human genome. At it is, we may have diverged to far from other species and lost our *real* genetic variation when we quit f'n goats. These labels cut to the bone.

 

There are theories of viruses adding DNA to the host cell genome. Species to species viral transmition could carry over genetic material that might find its way into gametes.

 

The food we eat, as well, is (almost) always of biological origins and contains DNA/RNA. This too could make it's way into the genome. I think it would manifest itself as a tumor rather than offspring with additional features. I don't know of any proved cases of this having naturally occurred, and I have seen no evidence that humans or any plants/animals share a common unique genome fraction. It is shown however that genomes are highly preserved, considering, and often these lowlevel genomea occupy the majority of all genomes. "Random" mutation (bit-flip, garbbly-goop, missense, tautology, repeat expansion, deletions) are contradictory to this fact.

 

A theory I am interested in is the potential for pseudo-intelligent-design. Whereby an organism actively scrambles DNA or proteins and somehow selects individual elements of its own (or something else's) genome. Like a super smybiotic anti-semetic amoeba. Intergalactic.

[Mr Skeptic]

A theory I am interested in is the potential for pseudo-intelligent-design. Whereby an organism actively scrambles DNA or proteins and somehow selects individual elements of its own (or something else's) genome. Like a super smybiotic anti-semetic amoeba. Intergalactic.

 

Are you referring to us? We're the only ones with the potential to do that, as far as I know, though it would not surprise me if some bug could occasionally gather DNA from some other creature. I started a thread on improving our own genes, and I'd be happy to get your input.

[foodchain]

I suppose anything is possible.

 

If mutations are to frequent, there won't be a window of opportunity for the changes to be scrutinized and then incorporated into the population.

 

It can be argued that in a spider ball of eggs there are, say, 1000 offspring. Of those 1000 there needs to be only 1 breeding pair to maintain the population. If there are 2 than the population experiences a vertical pattern. As the world is not full of spiders, we can assume there is an equilibrium being maintained. We further make the assumption that this equilibrium maintenance is filling the role of "natural selector".

 

Anyways, there can be a greater genetic drift in a species that has 1000 offspring. If 500 are a little f'd up and 100 are really f'd up that is O.K. It is sloppy and it turns out that's not what happens -- although mass producing animals do tend to experience more genetic "instability". "Instability" does rise in domesticated environments. This is more due to the laxing of the ordinary breeding pressure allowing the population to settle in at the lower standard.

 

A human has 46 chromosomes. Other primates have other numbers. The addition/subtraction of chromosomes and cross-species-breeding does yield viable offspring in primates and other mammalian species. In humans however any substantial chromosome remove is deleterious. The condition of have an additional redundant chromosome is also harmful, and often not viable much less capable of reproduction. Exactly what biological mechanism redundant-but-not-identical-chromosomes ?

 

It seems as though this would be easier if coding DNA and structural DNA were somehow separated. And they are, and this separation is on the chromosome itself. I don't know that the structure portions don't refer to coding on other chromosomes.

 

The X chromosome seems to be a very important, highly utilized chromosome. Many structural traits have been identified as residing on this chromosome, partly because of the unique way in which it is inherited. This unique inheritance also has the potential to stave off the polarity of sexual reproduction. So this unique virtual-mono-chromatin has a purpose and still undergoes genetic recombination. Defects on this chromatin are exaggerated in males. When there are two copy of a gene, one is defective, a defective protein will be made half the time. This allows for survival in sort of a "safe mode". Any sibling who has no defect is more likely to thrive -- evolution depends on this. It is highly unlikely the Y-chromosome does much of anything but sit next to X. I don't think another vestigial chromatin will find it's way into the genome.

 

But still the question may not be "where is my John Wayne?" but "where is Dr. Cornelius and the Ferengi?" as cross-"species" breeding may be the only way to add material to the human genome. At it is, we may have diverged to far from other species and lost our *real* genetic variation when we quit f'n goats. These labels cut to the bone.

 

There are theories of viruses adding DNA to the host cell genome. Species to species viral transmition could carry over genetic material that might find its way into gametes.

 

The food we eat, as well, is (almost) always of biological origins and contains DNA/RNA. This too could make it's way into the genome. I think it would manifest itself as a tumor rather than offspring with additional features. I don't know of any proved cases of this having naturally occurred, and I have seen no evidence that humans or any plants/animals share a common unique genome fraction. It is shown however that genomes are highly preserved, considering, and often these lowlevel genomea occupy the majority of all genomes. "Random" mutation (bit-flip, garbbly-goop, missense, tautology, repeat expansion, deletions) are contradictory to this fact.

 

A theory I am interested in is the potential for pseudo-intelligent-design. Whereby an organism actively scrambles DNA or proteins and somehow selects individual elements of its own (or something else's) genome. Like a super smybiotic anti-semetic amoeba. Intergalactic.

 

I like to think of natural selection as the sum of variables contributing to an organism. In which you could look at something like finding a niche by being a bottom feeder as a series of natural barriers a organism has to overcome in time. So in time you have variation which is inheritable, like DNA for instance. This variation meets various selective barriers and subsequently they interact, such as fungi behavior. In time you find specialization or niche occupation. These barriers if you will I think resonate in overall phenotypes, such as why do aquatic organism appear the way they do compared to terrestrial versions. Why the difference in life if environment held no sway. So basically having mutation is a gradual way to overcome such barriers hopefully but not always, and once past is sort of locks itself down into a stable pattern in the ecology and persists via reproduction. I think this is evident in trophic behavior also is in you don’t have autotrophs and then elephants. So a neat sci fi question would be what would life really look like on say Jupiter.

 

If life were not mutable it would not be able to adapt. You would not be able to get from fish to lion in time. The mutation process though is complicated, in that variance to mutation exists and that overall such a process is random. Basically if life did not have repair mechanisms or ability to cut down on mutation probability has it as life would quickly evolve towards extinction. On a side note rapid environmental change typically only leads to extinction. This to me subsequently speaks I think on the reality of mutation and NS.

[Mr Skeptic]

On a side note rapid environmental change typically only leads to extinction.

 

Only if there are no individuals that will be able to survive it. Sexual reproduction is there to allow rapid adaptation. You can draw on the gene pool of an entire species in a matter of one or two generations.

[foodchain]

Only if there are no individuals that will be able to survive it. Sexual reproduction is there to allow rapid adaptation. You can draw on the gene pool of an entire species in a matter of one or two generations.

 

Mass extinction events are named I would think properly and typically rely purely only one environmental conditions. The ability for life to persist has brought it past such situations and of course looking at just variation today its easy to see how but the extinction event still holds none the less. The relationship between and organism and its environment is a focal reality of life.

[Mr Skeptic]

Many went extinct in the mass extinctions, but others did not. Does that not show that some species are able to adapt rapidly?

[foodchain]

Many went extinct in the mass extinctions, but others did not. Does that not show that some species are able to adapt rapidly?

 

I would say that would have to be taken specie by specie along also with the extent of the change or environmental impact on life. Obviously bacteria can adapt rapidly and they are alive. I mean plants survive different then animals, if in a certain situation plants survive better then animals when faced with adaptation could also be just that case I would think historically speaking. I mean could an environmental change come about that is particular mean towards epiphyta?

 

*I have to go for a bit now.

[vampares]

OK I found an instance of genome hopping.

bird>human (via virus?)

If I'm reading this correctly it causes cancer. No wings, yet.

http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=164757

 

Selection, natural or otherwise (I think personal selection i.e. males ramming heads, or plumage and song, plays an integral role in higher organisms) does define a species. Whether this leads to evolving, I am not sure.

 

"Mutation", however, is a statistically poor way to achieve this although not impossible. First, a mutation might not do anything, it which case it goes unrecognized. When it does do something it tends to be bad. Second that bad mutation may go unchecked. Until it is coupled with a good one, which is selected for, and inbreeding takes down the whole ship. This puts a painstaking emphasis on probability, the size and scope of the gene pool, etc.

 

And I wonder how many parts of the human genome are rendered vestigial, ie, a protein is produced but is broken and has been that way since monkeys and so this protein just wastes space and resources in cells. If mutation is a frequent determinant, there may be a number of these "broken" proteins, and common to monkey too.