Are mutations mistakes?

[mark kennedy]

Except of course in nylon eating bacteria.

Do tell...

 

[notto]

Do tell...

Has natural selection eliminated the mutation that allows bacteria to digest nylon?

 

[mark kennedy]

Has natural selection eliminated the mutation that allows bacteria to digest nylon?

I don't know but natural selection keeps bacteria from being anything else other then bacteria.

 

[gluadys]

Then we are not talking about a mutation were are talking about a variation.

Yes we are. A variation in DNA is a mutation.

You know me so well it is scary.

Gee, honey, we've got to stop meeting like this.

I don't have the time to look this up but I am wondering what this has to do with mutations.

Well, when you do have time, look up "mitosis" (normal cell division) and "meiosis" (cell-division for reproduction.) The process of meiosis means that every chromosome has a 50% chance of occurring in any one gamete. And that in the production of gametes about 50% will have the paternal chromosome and 50% will have the maternal chromosome. So if a mutation has occurred (or occurs during cell division) on the paternal, but not the maternal chromosome, it has a 50% chance of appearing in each gamete produced by the germ cell when it undergoes meiosis.

Do you want to cite a source or should I take you're word for it?

Take Mendel's word. Remember your Punnett square and the distribution of maternal and paternal genes to the offspring?

Deletion, insertion or what?

Doesn't matter what kind.

Individules must evolve or the mutations that are given so much credit are nothing.

No, individuals do not evolve. No matter what happens to them during the course of their lifetime they die with the same genetic pattern they received on conception. But if a change occurs in a germ cell which goes on to participate in a reproductive event, the child inheriting that change has a new genetic pattern. That is an initial step in spreading the change through the species.

I am still waiting for someone to tell me how they are acumulated since natural selction eliminates them.

You think that because you never went through with the experiment I asked you to try using Mendel's laws in conjunction with selection pressure (something Mendel never did himself.) You could demonstrate to yourself quite simply that natural selection does not eliminate beneficial mutations if you tried that experiment.

It takes a bit of math, but it's not very hard, since even I can do it. In fact, I have to do the math the slow way with simple arithmetic, when it could probably be done much faster with algebra. But the results are the same.

Let me know if you want to give it a try.

 

[notto]

I don't know but natural selection keeps bacteria from being anything else other then bacteria.

Is that a shifting of the goalposts or just a pointless comment that has nothing to do with your comments about natural selection eliminating the accumulation of mutations?

 

[mark kennedy]

Yes we are. A variation in DNA is a mutation.

Yes but it does not mutate the strain in order to evolve. In fact, it can't.

Gee, honey, we've got to stop meeting like this.

cute...

Well, when you do have time, look up "mitosis" (normal cell division) and "meiosis" (cell-division for reproduction.) The process of meiosis means that every chromosome has a 50% chance of occurring in any one gamete. And that in the production of gametes about 50% will have the paternal chromosome and 50% will have the maternal chromosome. So if a mutation has occurred (or occurs during cell division) on the paternal, but not the maternal chromosome, it has a 50% chance of appearing in each gamete produced by the germ cell when it undergoes meiosis.

Sometimes I wonder if you are trying to refute me or just educate me. Now a mutation occures on a level of 1 in 10,000 to 1 in 100,000 replications. For the most part they do not have any effect at all but sometimes they do. What are the odds of them having a beneficial effect?

Take Mendel's word. Remember your Punnett square and the distribution of maternal and paternal genes to the offspring?

How could I forget?

Doesn't matter what kind.

Of course it does.

No, individuals do not evolve. No matter what happens to them during the course of their lifetime they die with the same genetic pattern they received on conception. But if a change occurs in a germ cell which goes on to participate in a reproductive event, the child inheriting that change has a new genetic pattern. That is an initial step in spreading the change through the species.

That makes no sense since populations are made up of indivudules.

You think that because you never went through with the experiment I asked you to try using Mendel's laws in conjunction with selection pressure (something Mendel never did himself.) You could demonstrate to yourself quite simply that natural selection does not eliminate beneficial mutations if you tried that experiment.

What are you talking about?

It takes a bit of math, but it's not very hard, since even I can do it. In fact, I have to do the math the slow way with simple arithmetic, when it could probably be done much faster with algebra. But the results are the same.

Let me know if you want to give it a try.

Oh that, I asked you to use HW egualibrium as a baseline and to tell me how the formula would look when the evolution of a transitional occured would look. Now while this was an interesting mind tease it is hardly an answer.

Allways a pleasure,
Mark

 

[Pete Harcoff]

I am still waiting for someone to tell me how they are acumulated since natural selction eliminates them.

It's a two step process. New genotypes are continually produced via reproduction & mutation in a population. Then, certain genotypes become fixed in a population, either through selection or genetic drift, while others are elimated.

For related reading, you might want to look at Fitness effects of advantageous mutations in evolving Escherichia coli populations. It demonstrates how beneficial mutations can become fixed in populations.

 

[gluadys]

Yes but it does not mutate the strain in order to evolve. In fact, it can't.

I have no idea what you are talking about or how it is relevant to the conversation. A change in DNA is a mutation in the sequencing of a gene or genes. It may or may not have a phenotypic effect. That is irrelevant to the definition of mutation.

If it does have a phenotypic effect, it is exposed to natural selection. That is the point at which it becomes evolutionarily significant.

Sometimes I wonder if you are trying to refute me or just educate me.

To educate. No question.

Now a mutation occures on a level of 1 in 10,000 to 1 in 100,000 replications. For the most part they do not have any effect at all but sometimes they do. What are the odds of them having a beneficial effect?

Depends on the nature and force of the environmental pressure. A mutation that is harmful or neutral in one environment may be beneficial in a different environment, and vice versa. e.g. a gene that confers resistance to toxins is beneficial to an insect exposed to pesticides, but it is merely neutral and even possibly harmful where pesticides are not being used.

Doesn't matter what kind (of mutation).

Of course it does.

Why?

That makes no sense since populations are made up of indivudules.

So tell me, how does a mutation in a germ cell contribute to the evolution of the individual possessing the germ cell?

Oh that, I asked you to use HW egualibrium as a baseline and to tell me how the formula would look when the evolution of a transitional occured would look. Now while this was an interesting mind tease it is hardly an answer.

Allways a pleasure,
Mark

Actually lucaspa did give you that equation at the time if you can find that thread again.

Wait. Here it is on this page.

Worth reading the whole page. The formula you are looking for, however, is way at the bottom.

 

[Pete Harcoff]

Sometimes I wonder if you are trying to refute me or just educate me. Now a mutation occures on a level of 1 in 10,000 to 1 in 100,000 replications. For the most part they do not have any effect at all but sometimes they do. What are the odds of them having a beneficial effect?

Unfortunately, there's not a lot of data for this (and I've been looking). The best data I've found is for e. coli (see my previous post) which puts the number of beneficial mutations at about 4x10^−9 per cell and generation. Compared to the overall mutation rate in e. coli, which is about 2.50x10^-3 per genome per generation, that means beneficial mutations are about 1 in 625000.

While this may seem incredibly small, it's important to note the population sizes we're dealing with (you've got billions of e.coli are in your intestines right now).

And while I'm sure if it's justified to do so, if I extrapolate relative to humans and we assume an effect mutation rate of 2 per person (which is fair, since I've seen estimates range from around 1.6 per person to over 4 per person), that means there's a beneficial mutation in every 312500 people (about 19000 benefical mutations in the total population).

Btw, take these numbers with a huge grain of salt. Mutation rates are variable and the data on beneficial mutation rates is, like I said, sketchy.

Note: If I pooched any math or numbers here, please correct me. I'm writing this after just finishing a 3 hour Calculus exam, so my brain isn't exactly eager to do more math right now.