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Author | Topic: Mutation | |||||||||||||||||||||||||||
crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
If you have an example of a beneficial mutation, please post, cause I really don't think there are any (one of many reason I don't belive in evolution). What is your definition of "beneficial"? I ask because if you're just going to define "beneficial" in such a way that no mutation could ever be beneficial, then there's no point in talking to you, right? Here's a start - biologists define "beneficial" as any mutation that allows an organism to generate more survivng progeny in a given environment. There's certainly plenty of examples of that:
Are Mutations Harmful? Now, do you agree with this definition? If not, why not? And if not, why should we use your definition over the more useful biological one?
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
That is a trait that already existed in the population. ...because of mutation. Remember that mutation is random and not generally driven by environment. Natural selection selects for traits that already exist; it doesn't create mutations to select. The trait was selected for because the environment changed. You're right that the trait already existed before the environmental change; the reason it existed is because of mutation.
The fact that that trait became dominant is an example of adaptation through natural selection. Obviously. But the fact that it existed in the population at all was due to a mutation.
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
First off, genetic traits don't have to be dominant to affect a population. I don't think that's what he meant - I think by "dominant" he meant that the frequency of that allele in the population increases so that it's the most common. I don't think he was actually referring to genetic dominance. Insofar as he meant that evolution is a process by which some alleles increase in frequency within a population's gene pool as a result of natural selection, I think that's the view of every evolutionist, not just many or most.
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
let him speak for himself instead of second guessing eh? If he doesn't know what genetic dominance refers to, he's not going to understand how you misunderstood him. I was just trying to facilitate understanding on both sides.
My point was that the phrase as written was not what a biologist would say. I think it's safe to say that sometimes we have to make allowances for people who may not be familiar enough with the sciences to get the terms right.
and it doesn't have to become the most common in a population either, it can remain in a varietal subset of the population that eventually accumulates with other changes to cause a speciation separation from the general population. At which point it's the defining feature of that population, which is what he was saying. Look, the guy's a crank, I'm sure, but misrepresenting what he was saying doesn't serve anybody.
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
Do we know of any? Well-developed throats, large areas of the brain devoted to language, upright posture, thin body hair, large male genitals, etc.
If mutations and natural selection are not the key ways that evolution occurs, what are? Those are the key ways that evolution occurs, yes. Reproductive isolation is the key way that new species form.
How can examples such as finch beaks be used as proof of helpful mutations when no new species is created? (By this, I suppose I am assuming that the helpful mutations create new species - please correct me if I am wrong). Yeah, you're slightly wrong. Mutations don't create new species by themselves. It has to be mutation occuring in a situation of reproductive isolation. An isolated subpopulation accumulates mutations that aren't shared with the main population until the subpopulation is no longer able to breed with the main population. At that point you have a new species. When did it happen? Well, that's about as hard to answer as "when did it start raining?" Speciation is the result of a process, not an event in itself.
Most mutations are harmful This is wrong. Most mutations have no effect on the organism.
but there are some that may, in some way, improve the organisms state of being. You might want to keep in mind that it's only the environment that determines whether or not a mutation is harmful, neutral, or beneficial.
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
How can one tell that the developed throats and brain are a result of mutations? Because that's the only observed mechanism for the introduction of genetic material into the gene pool of a population. The alternative is that humans have always had these genes because humans were created with them, but we've never observed a mechanism that can create an organism wholesale from scratch.
Isn't it true that mutations are rather rare? No, they're quite common. You probably have between 50 and 500 (rough estimate) mutations of your very own. Obviously they're neutral ones, or else you'd notice. Then again there's the occasional human with a noticable mutation, like a lack of wisdom teeth.
How could the evolution of a species occurred if only a few, or a single species got that genetic mutation? Wouldn't the greater population of other (birds for example) make it so that the new mutated form would never get a chance to gain into a majority Sometimes that happens. But a beneficial mutation is one that allows that organism to leave more progeny than it's competitors. Therefore by definition the mutation will become more common because individuals with the mutation are outcompeting and outreproducing the individuals who lack it. Remember also that it isn't "muties vs. normals." The individuals without the mutation don't band together against the individual with it. They're competing against each other, too.
Even then, isn't it a bit extreme to say that all evolution happened due to reproductive isolation (maybe you don't say this, but that's what you seemed to imply)? All speciation happens as a result of reproductive isolation. Huh, I'm surprised you missed that; I thought I had been pretty clear about it. Evolution is when allele frequencies change within a gene pool. Speciation separates gene pools permanently (which can change allele frequencies.) Reproductive isolation interrupts gene flow, which allows speciation to occur.
And please pardon my ignorance, but how is it that the environment determines the outcome of mutations? By selection. Beneficial mutations are mutations that are selected for. Harmful mutations are mutations that are selected against. Of course, it's not like the environment is picking and choosing, any more than the roulette wheel "chooses" where the ball lands. Selection is just the name we give to the observation that organisms adapted to their environment tend to leave more offspring than the ones that don't. For instance - what if you had a mutation that gave you thick, insulating fur? Is that a beneficial mutation or a harmful one? Kinda depends on whether you live at the North Pole or in Africa, doesn't it?
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
How might one define a mutation? Any sequence of genetic code that you didn't inherit from either of your parents.
What are some common day examples of beneficial mutations in humans? People with no wisdom teeth. There's a number of mutations, I believe, that confer degrees of resistance to various diseases, like the gene for sickle-cell anemia.
Aren't most mutations sterile, or unable to reproduce? Certainly not. You have somewhere between 50 and 500 mutations of your very own, and I assume you have no reason to doubt your fertility?
I thought that mutations more often take things away than provide new, helpful things. All mutations have the potential to do is change how protiens are created, because that's all genes do - code for protiens.
It seems like when people refer to "beneficial" they mean two things: Helpful to the organism, and able to make reproduction faster and more numerous. Is this equiviating on the term? Not exactly - it's generally possible, given a substantial enough mutation, to predict how it might interact with the environment. For instance in an environment dominated by nylon oglimers, a mutation allowing a bacterium to digest them is likely to be beneficial indeed. Ultimately, though, you have to go by the results - does that gene spread through the gene pool, or is it eliminated?
For example, when mutations take out teeth, that is not exactly beneficial, is it? Ask somebody with impacted wisdom teeth if not having them would be beneficial. In an environment of cooked, soft food leading to smaller jaws with less room for teeth, less teeth is beneficial indeed. The problem is that, as humans, we pre-empt natural selection. We don't allow selection to occur, so ultimately it's not possible to use "beneficial" properly in regards to human mutations. Human allele frequencies change in ways that have nothing to do with natural selection or adaption to environment.
What would you say is the difference between evolution and speciation? Evolution is the process by which allele frequencies within a gene pool change. Speciation is the process by which gene pools sepearate into separate pools. If you're not looking at evolution from the perspective of population genetics, you're not looking at it the right way.
If so, what is the organism evolving into that is new? Organisms don't evolve. Only populations do.
Finally, are evolutions and mutations somewhat synomous, or is there no direct relation? Mutations are novel gene sequences not inherited from either parent. Evolution is a change in allele frequencies. The source of new alleles is mutation, but mutation isn't responsible for the shift in frequency - that's a function of natural selection. It is safe to say that mutation + natural selection = evolution.
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
That is a really lamentable oversimplification of things. Perhaps you're right. Nonetheless I think it's useful to take a step back and consider what is really meant when we say "this gene codes for such-and-such." Otherwise one is liable to conflate the complexity of a structure with the complexity of the gene controlling it, which leads to dumb questions about how much complexity mutation can be the source of, etc.
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
I think that the complexity of consequences arising from a specific mutation is a reasonable thing to think about, as long as people realise that the answer is going to be different for almost every gene. With that caveat, I agree.
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
The people with no wisdom teeth example you sited is not necessarily beneficial Again, it depends on environment. For people whose jaws are too small to support that many teeth, not having them is beneficial. But rememeber that humans are no longer subject to the stricter forms of natural selection. The only selection occuring on most humans is sexual selection, really.
I believe I have heard it said that only about 1/5 of people actually have problems with their wisdom teeth I don't have the stats, myself. I know that mine were removed, so clearly it would have been to my benefit to not have themat all.
With my question about mutations being sterile, I simply meant I didn't think that those mutations were passed on to various generations in a beneficial way, if at all. You're going to have to explain this. What would prevent a mutation from being passed on? The only mutations we're concerned about are the ones that happen to the fertilized zygote (or during the formation of the gametes in the parents gonands). Since the entire organism is composed of the decendants of that cell, every cell in the organism, including the gametes (well, the ones with the chromosome in question, which would be half of them) will contain the mutant gene. Where's the problem to heredity, here? I guess I don't understand your point.
The way one determines how a mutation is beneficial seems somewhat abitrary, since it relies on the environment. Removing that variable, is it impossible to determine if a mutation is beneficial or not? You can never take away environment. You can only change environment. An animal in a scientific pen is still in an environment. What would be arbitrary would be subjective judgements about what is beneficial or detrimental. Considering mutations in relationship to the environment is the only objective measure of the eventual success of a mutation.
Would this mean that I could not evolve, but my son could? No... but mutations in your son could represent the evolution of the human population. Your son will always be himself. He'll only change insomuch as humans change throughout their lives. That change will never represent an evolution of your son. It's the difference between your son and you that represent the evolution of the human species.
Then the cell would produce the wrong sorts of products, or starve and harm the body. Or, confer resistance to disease or give the cell the capability to use a new substance as a metabolic fuel. Or do nothing at all.
While I do not completely understand how what they are describing works, it seems clear that mutations are somewhat harmful. Again, you seem to be generalizing - because many mutations are harmful or even fatal, you seem to think they all must be.
It made me wonder: if we as a guiding intelligence can't even produce a new species of flies by mutations in a lab New species of fruitfly? We do that all the time, through reproducive isolation:
quote: From Observed Instances of Speciation Remember, it's not the process of mutation alone that gives rise to new species. It's mutations accruing in a situation where gene flow is interrupted (reproductive isolation.)
Are there any examples of major mutations leading to new classes and phyla (when it would be necessary to even create new Kingdoms for the evolutionary theory held today to have credibility? Here's one, from the same link:
quote: To me, it seems like evolution by mutations is self defeating. Only if you assume that all mutations are negative. For some reason we don't seem able to disabuse you of this notion, no matter how many examples of benefical mutations we show you. Why is that?
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
I'd say wisdom teeth really has been an advantage up to modern time. Well, of course. But the environment changed, and now we no longer need extra teeth to replace the adult teeth we were expected to lose. Mutations are benefical ultimately only in regards to environment.
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
And, Generally speaking, MOST new mutants are lost anyways, even beneficial ones. Then they weren't, by definition, beneficial. I don't entirely understand how you came to the conclusion that most beneficial mutations are still fatal. The question is, did the mutation allow the organism to leave more viable offspring than the competition (that is, every other conspecific)? If the answer is "yes", the mutation was beneficial, and evolution occurs.
How many times do these hard to know rare occurrences that can be lost have to happen to result in say a wingless creature to slowly evolve a wing nub (nub as in the very early stages of a "potential" wing evolving, NOT to say that a wing WILL evolve.) ? Wings don't evolve from nubs, particularly in vertebrates. In vertebrates they evolve from arms. Show me a vertebrate with both arms and wings. I don't know how they evolve in insects, but I could probably find out from one of the books my wife has.
Even with 40 Billion years, the idea that these rare occurrences can evolve into what we know of the world today is still not plausible for me. How much time do you think it would take, then?
"Quite often a mutation occurs within a population and then disappears because the organism had no offspring or didn't happen to pass the mutation on to its offspring; this can happen even if the mutation is beneficial." Call me strict but I think that's an erroneous use of "beneficial". If it didn't help the organism, then there's no way to say that the mutation was beneficial. Obviously, accidents happen. Not all death is selection - sometimes you get hit by a rock or something.
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
I said that they can still be lost. But that only happens when the organism dies before leaving offspring. So you'll excuse me if I took what you said to mean that even benefical mutations mostly kill the organism, which doesn't make any sense. What did you mean by "lost", otherwise? Where do you think they go?
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
I actually didn't know that.
Interesting. But with so many mutations happening per organism - hundreds, usually - a two percent fixation rate is still a lot. For instance, that's two of your own mutations being fixed in the population.
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crashfrog Member (Idle past 1487 days) Posts: 19762 From: Silver Spring, MD Joined: |
What do you all think of Dr. Michael's Behe's argument of Irreducible complexity, which he sets forth in Darwin's Black Box? I think evolution has no problem with "irreducable complexity." Consider that the stone arch, the foundation of cathedral design, is irreducabl complex - remove any one stone and the arch collapses. Yet, arches are constructed one piece at a time. Reflect on how this is done and you will see that irreducably complex systems pose no particular challege to evolution.
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