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Thread: MUTATIONS

  1. #1 MUTATIONS 
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    These mutations I keep hearing and reading about ? I keep thinking that a mutation is some kind of accident. Or a random change in biological makeup. And then somehow, this mutation keeps on popping up in further generations, the mutation itself mutating as it goes along, e.g. this rib/spine on the anglerfish getting longer and longer. And the few fish that do possess it out of the vast population, because as a mutation the whole of the population will not be developing it I assume, they are passing it on to further generations. Resulting in anglerfish with the mutation and anglerfish without. There's no reason or benefit for thousands of years.

    In the case of the anglerfish, it only becomes useful when it gets to a certain length and develops the ability to glow in the dark !

    So for the thousands of years the mutation is developing it serves no useful purpose what so ever, it's almost as if, hey, this long dangly thing came in useful after all to hang a light on because it's so damn dark down here.

    Is any of this correct or incorrect ?


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    Forum Freshman Samuel P's Avatar
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    I've been taught that a mutation is a genetic 'throw-up' e.g. a frog is born that has a longer tongue than others, it catches more food and lives to reproduce. It is naturally selected over the others in the species to pass on its genes to later generations. This means that more frogs are born with longer tongues, evolving the species over a long long period of time.

    In the case of the angler fish, I would believe that he was naturally selected (when I say he, I mean the one with the longer rib/spine) meaning that he passed on his genes.

    From all the information I have, you sound pretty correct.


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    As well as your frog example I think I have another but with a question thrown in at the end which I hope is relevent.

    I was watching a TV program showing how on this beach there were 3 types of birds. Short billed, long billed, and bills inbetween. According to the comentator, the 3 bill variation ensured there was food enough for the 3 types of birds. Apparently all these birds had short bills to begin with for surface feeding, but as the population grew the food became scarce.

    Some birds were born with slightly longer bills, mutations, such birds could dig a little bit deeper than there brothers and sisters and so they found food further down in the sand which meant they survived, and it also took the pressure off the surface feeders. Of course, the food just below the surface became scarce and so again, birds with longer bills still had a better chance of digging even deeper. They get food, and take the prssure off the middle and surface feeders and so on. So the 3 birds now live happily alongside each other, top feeders, middle feeders, and deep feeders.

    Over thousands of years I can see this happening. The variations in leg length and plummage also changed too.

    Now my question, are these birds still evolving due to mutational changes ? I ask because if we look at the animal/bird/fish/insect/ world, everything seems to have developed perfectly well for life on earth. Everything has a place and it seems there is a place for everything. Can biologists determine the answer to my question or would we have to be around in thousands of years to compare ??

    BARCUD
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  5. #4 Re: MUTATIONS 
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    Quote Originally Posted by BARCUD
    These mutations I keep hearing and reading about ? I keep thinking that a mutation is some kind of accident. Or a random change in biological makeup. And then somehow, this mutation keeps on popping up in further generations, the mutation itself mutating as it goes along, e.g. this rib/spine on the anglerfish getting longer and longer. And the few fish that do possess it out of the vast population, because as a mutation the whole of the population will not be developing it I assume, they are passing it on to further generations. Resulting in anglerfish with the mutation and anglerfish without. There's no reason or benefit for thousands of years.

    In the case of the anglerfish, it only becomes useful when it gets to a certain length and develops the ability to glow in the dark !

    So for the thousands of years the mutation is developing it serves no useful purpose what so ever, it's almost as if, hey, this long dangly thing came in useful after all to hang a light on because it's so damn dark down here.

    Is any of this correct or incorrect ?
    In most cases, changes such as the one you describe do need to confer some advantage in order to be passed on. That isn't an active process, it's just that the change makes the carrier more likely to survive long enough to reproduce.

    But the change doesn't have to be very beneficial to be passed on for a few generations. In fact, it could be entirely neutral to selection (no advantage or disadvantage) or could even be quite detrimental (hampers survival). In natural selection, survival is a probability- not a certainty either way. Let's imagine for a moment that the elongated spine is a disadvantage by itself. If, by chance, you survive long enough with the "bad mutation" to reproduce, then that bad mutation has another chance in a new generation to undergo a further mutation. And of course, with several offspring, the chance that the bad mutation will make it to generation three, four five... is slightly enhanced.

    On average, if nothing improves, that bad mutation will either persist in the population at a very low frequency, or simply disappear because all carriers are selected against (they die before reproduction). These are the most common outcomes of a detrimental mutation. However, if one of the offspring in a following generation undergoes a mutation that changes that elongated spine into a benefit, then that individual will suddenly have a selective advantage, a better chance at survival and reproduction. The coupled "bad" and good mutations will increase in frequency in the population.

    The more complex structures and biochemical cascades seen in organisms are probably made up of of mutations that were a mixture of "good" (positively selected), neutral and bad (negatively selected). The role of chance in evolution is significant.
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    Forum Cosmic Wizard spuriousmonkey's Avatar
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    mutations are the norm. That is the biological copy machinery isn't perfect. Every time a cell divides it creates a series of mutations.

    Therefore it is good to view the concept of mutation as something basic and essential to the system of replicating life, and not as something weird, detrimental and nasty.
    "Kill them all and let God sort them out."

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    Forum Freshman Samuel P's Avatar
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    I believe mutations to be completely unpredictable. Over millions and millions of years the 'best' mutations have been chosen or naturally selected to be passed on, as they are the most beneficial.

    Things are still evolving, but comparing it to the actual time we live, I doubt we'll ever see it.

    I'm thinking anyway!
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  8. #7 Re: MUTATIONS 
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    Quote Originally Posted by BARCUD
    In the case of the anglerfish, it only becomes useful when it gets to a certain length and develops the ability to glow in the dark !
    No, that's not true. Any advantage whats so ever becomes selected, even the smallest advantage gets propagated through the gene pool, even ones we cannot detect or define as advantageous, just by sheer chance that 1 out of a thousand gets more food to eat or more mates, because of the small modification to an appendage. Now, that doesn't mean the lineage will survive and evolve; other factors are at work. And so if further genetic mutations in the successful lineage cause a larger appendage that makes it 2 or 3 out of a thousand, then there is a greater change the lineage contributes to the gene pool. Still other factors are at work. Some are catastrophic causing significant abrupt changes in relatively short time. We only see the end result and have difficulty understanding how the end product emerges from the individual changes.
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    Hi, I still find parts of this difficult to grasp.

    The giraffe, obviously the longer necked giraffes were able to reach food that was higher up trees, the ever evolving length of the neck served a purpose and so passed on. Those giraffes with longer necks survived and passed on this mutation to further generations. The elephants trunk - the lizards tongue - the sandpipers long bill - it is obvious how and why these characteristics developed through mutation. They benefitted the species and ensured survival.

    BUT, there is absolutley no reason why a small bump, perhaps the size of a pimple, on the back of an anglerfish should prove beneficial or ensure the survival of its owner. If it served no purpose then why would it be passed on from generation to generation increasing in length over thousands of years ?

    http://www.seasky.org/deep-sea/angler.html

    BARCUD
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  10. #9  
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    Quote Originally Posted by BARCUD
    Hi, I still find parts of this difficult to grasp.

    The giraffe, obviously the longer necked giraffes were able to reach food that was higher up trees, the ever evolving length of the neck served a purpose and so passed on. Those giraffes with longer necks survived and passed on this mutation to further generations. The elephants trunk - the lizards tongue - the sandpipers long bill - it is obvious how and why these characteristics developed through mutation. They benefitted the species and ensured survival.

    BUT, there is absolutley no reason why a small bump, perhaps the size of a pimple, on the back of an anglerfish should prove beneficial or ensure the survival of its owner. If it served no purpose then why would it be passed on from generation to generation increasing in length over thousands of years ?

    BARCUD
    I explained that to you already. Read my post above. It doesn't need to confer a strong advantage or even any advantage at all to be passed on at a low frequency, it need merely not be disadvantageous enough to cause the gene to be deleted by natural selection. A gene that is largely neutral with respect to selection will undergo what is called genetic drift, settling into an equilibrium in the population over time.
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    Quote Originally Posted by BARCUD
    Hi, I still find parts of this difficult to grasp.

    The giraffe, obviously the longer necked giraffes were able to reach food that was higher up trees, the ever evolving length of the neck served a purpose and so passed on. Those giraffes with longer necks survived and passed on this mutation to further generations. The elephants trunk - the lizards tongue - the sandpipers long bill - it is obvious how and why these characteristics developed through mutation. They benefitted the species and ensured survival.

    BUT, there is absolutley no reason why a small bump, perhaps the size of a pimple, on the back of an anglerfish should prove beneficial or ensure the survival of its owner. If it served no purpose then why would it be passed on from generation to generation increasing in length over thousands of years ?

    BARCUD
    Sometimes a relatively small genetic change can have very pronounced effects, as can readily be seen with deformed children born of parents that were victims of Chernobyl for example. Similarly, one mutation could have been enough to at least extend the spine by quite a margin, if not all the way. The chemical light producing organ might have been utilised somewhere else on the body and migrated over time onto the tip, or again, in one generation.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

    "Gullibility kills" - Carl Sagan
    "All people know the same truth. Our lives consist of how we chose to distort it." - Harry Block
    "It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle
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  12. #11  
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    Quote Originally Posted by BARCUD
    BUT, there is absolutley no reason why a small bump, perhaps the size of a pimple, on the back of an anglerfish should prove beneficial or ensure the survival of its owner. If it served no purpose then why would it be passed on from generation to generation increasing in length over thousands of years ?
    BARCUD
    also, remember that an organ in an earlier state does not necessarily ahve to be used for the same function as it is now

    e.g. one of the theories about the development of insect wings is that originally they may have acted as solar panels to help the insect warm up in the sun; this function was later on overtaken by the flight function

    so if you're going to ask "what good is a smidgen of a wing?" then the answer has to be "for flying, not much, but for the overall survival capability of the insect, a lot"

    likewise, angler fish may not initially have used the spine as a lure, but if decorated in some fashion might have attracted the attention of a passing fish which could then be surprised and swallowed in one gulp - remember also that not all angler fish are denizens of the deep : some lay in waiting in shallow waters with very little visible but the spine (remember also that they have very wide mouths, and it only takes a fish to come relatively nearby for it to be swallowed)
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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    [quote="BARCUD"]
    I was watching a TV program showing how on this beach there were 3 types of birds. Short billed, long billed, and bills inbetween. According to the comentator, the 3 bill variation ensured there was food enough for the 3 types of birds. Apparently all these birds had short bills to begin with for surface feeding, but as the population grew the food became scarce.
    [quote="BARCUD"]

    In ecology,every species have one kind of niche in nature to avoid the competent of the similar species.

    Quote Originally Posted by BARCUD
    Now my question, are these birds still evolving due to mutational changes ? I ask because if we look at the animal/bird/fish/insect/ world, everything seems to have developed perfectly well for life on earth. Everything has a place and it seems there is a place for everything. Can biologists determine the answer to my question or would we have to be around in thousands of years to compare ??
    BARCUD
    My major is fishery science but not a biologists.I think,every species semms evolving to adapt to the selection of nature.Nature as the outer pulse,also play an important role in mutational changes of species.If we enlarge our eye board to human society,for thousands of year our ancients also evolved into the phase of learning or micicing(?) the other specing behavior,such as the schooling behavior of bee,and we called it knowledge which is now hamorized the relationship each other in our society.Take another example,China had opened the door to the world for 30 years.In the past 30 years,we children were asked to learn English from 10 years old in order to keep the path with the science advance of English-speaking country.Although I am not English speaker,I still have to learn speaking in the Chinese speaking country.Is it social selection decided by our country leader for our society?Sometimes I keep feeling inferior to TaiWan Chinese in traditional culture.
    Regards
    Min Xu
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    I also struggle to understand this issue.

    Random mutation with continual copying is understandable.

    However, take the example of the giraffe - if the female giraffe's genes mutate to randomly produce a very slightly longer neck, the female may have an advantage - to live long enough to mate - but the offspring would inherit both (non-mutated) male and (mutated) female genes - the advantageous mutated gene may not be dominant to the male's standard genetics and the chances of the offspring gaining the advantage must be miniscule.

    The odds of ending up with the modern giraffe (and any defined species), from a common anscestor must be minute!
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    Mutation - is it not also the case that mutation can only occur when genetic information is lost - new genetic information cannot be gained ??
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    On issues of genetic mutation,I also struggle to understand what they said above.
    In cod fisheries, in 1600s, the total length of cod catched by men is more long than in 1990s.Owing to overfishing, cod fisheries is collapsed by 1990,so countries around Atlantic Ocean decide to ban any forms of cod fisheries.However,although ten years passed away,cod resource still unrecover.Scienties said, total length,breed capability of cod genes had been changed by cod fisheries for more than 500 years.Mature adult could not arrive at the fork length of cod in 1600s,so they breed small eggs, offspring be low survivities.I think maybe this is good example to explain animal mutation in case of men power.
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  17. #16  
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    Quote Originally Posted by suziwong
    I also struggle to understand this issue.

    Random mutation with continual copying is understandable.

    However, take the example of the giraffe - if the female giraffe's genes mutate to randomly produce a very slightly longer neck, the female may have an advantage - to live long enough to mate - but the offspring would inherit both (non-mutated) male and (mutated) female genes - the advantageous mutated gene may not be dominant to the male's standard genetics and the chances of the offspring gaining the advantage must be miniscule.
    You should think about this topic in terms of population dynamics.

    There is always a distribution of variation within a population, with many traits following something like a bell curve.

    This curve can shift either way, for example on average a longer neck, or shorter neck depending on the entire distribution of the genetic trait in the population.

    It doesn't even matter whether a genetic trait is dominant or not.


    Imagine the following experiment: take a population of fruit flies and kill all the small ones. The curve has now shifted towards the 'large' phenotype (in fact it got narrower also).

    Do not change anything to the environment, and what will probably happen is that over a few generations the curve will start expanding towards the 'small' phenotype.

    Assuming of course there is some restriction that prevents the curve going towards 'larger'. That could also happen of course. It could be the push that was needed to get the entire population going towards a larger phenotype.

    confusing isn't it.
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  18. #17  
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    Quote Originally Posted by suziwong
    I also struggle to understand this issue.

    Random mutation with continual copying is understandable.

    However, take the example of the giraffe - if the female giraffe's genes mutate to randomly produce a very slightly longer neck, the female may have an advantage - to live long enough to mate - but the offspring would inherit both (non-mutated) male and (mutated) female genes - the advantageous mutated gene may not be dominant to the male's standard genetics and the chances of the offspring gaining the advantage must be miniscule.
    genetics is not like mixing paint, as Mendel's original experiment already proved : he mixed yellow and green peas and ended up with all yellow in the first generation and a 1-to-3 ratio of green and yellow in subsequent generations
    + you forget that natural selection weeds out the less successful from your varied sample and directs it to a population where the more successful predominate

    Quote Originally Posted by suziwong
    The odds of ending up with the modern giraffe (and any defined species), from a common anscestor must be minute!
    the odds of any creature evolving from an ancestor is minute, but then again so is the chance of winning the lottery, and still some people do

    Quote Originally Posted by suziwong
    Mutation - is it not also the case that mutation can only occur when genetic information is lost - new genetic information cannot be gained ??
    no - mutation is just a mistake in the copying process
    this mistake may be a deletion, but can also be a substitution or even a duplication or an insertion
    it does not necessarily follow that information is lost
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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  19. #18  
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    In the event that a new beneficial mutation is recessive then it won't be expressed in the first generation. The gene will absolutely be inherited, but if entirely recessive, will not be subject to selection until such time as the gene is common enough in the population to be inherited homozygously and thus expressed.

    Quote Originally Posted by suziwong
    Mutation - is it not also the case that mutation can only occur when genetic information is lost - new genetic information cannot be gained ??
    No, it is not the case. Genes do not have an inherent "information" property. Their information content is determined by expression and selection. In that respect, it is entirely possible for a mutation to confer "new information". This has even been directly observed by experimentation. Check out Lenski's 2008 paper on the emergence of new metabolic pathways in E.coli.

    The "no new information" argument was cooked up by creationists like William Dembski. He essentially hijacked elements of information theory and tried to apply them to genetics in such a manner as to suggest that the information complexity was too great to emerge by random mutation and selection. This is has been trashed not just by biologists but by information theorists also.
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