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Author | Topic: the phylogeographic challenge to creationism | |||||||||||||||||||||||
NosyNed Member Posts: 9003 From: Canada Joined: |
If the scientists insist on being scientifically exact I will give up or take the discussion to the religion side of the board. Snowing nonscientists under with scientific technicalities, burying the forest in the trees, and berating them for their failure to use scientific concepts as scientists do IS belittling them. I have to break this to you. What you have been given is the simplified, digested, made-easy explanations for things. You are not being snowed under with technicalities. You level of misunderstanding is not at the technical details level. If you had the faintest idea of what the technical details (the "trees" ) were you wouldn't be saying the above. You are the one making firm statements about what is and isn't true. If anyone is belittling you it is for doing that when you know only very, very little about the subject and some of what you "know" is completely wrong.
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crashfrog Member (Idle past 1489 days) Posts: 19762 From: Silver Spring, MD Joined: |
Is this necessary? Ask her. Or did you not notice that I was repeating her remarks to me? If you're concerned about the direction the tone of the thread is taking, look to the one that instigated it, not me.
She wants to respond to several evo posters, and if crash or someone has to resort to cussing her out to make his point I didn't resort to it. Faith finally responded to many, many posts where I patiently explained her error by berating me and admonishing me to "make an effort", as though it's somehow my problem that she doesn't know how to use words in the English language.
My suggestion is to allow that discussion to take place among parties interested in doing so in a civil manner. I was so interested; right up to the point where Faith abandoned civil dialogue with me. Don't try to make this out to be my fault.
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AdminRandman Inactive Member |
I was addressing the tone of sections I quoted, not the content. I am not saying anything about the entire thread, or saying it's all your fault or anyone's fault. Just want to keep the dialogue civil.
I do think if there is substantial dialogue taking place in a civil manner between Faith and a few other posters, it would be gracious of you or anyone to let them go down that path, as I am sure some of the others are well-versed in the evo-side of things and can and will bring up points you would have as well. That goes for everyone, btw, not just you.
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crashfrog Member (Idle past 1489 days) Posts: 19762 From: Silver Spring, MD Joined: |
I do think if there is substantial dialogue taking place in a civil manner between Faith and a few other posters, it would be gracious of you or anyone to let them go down that path, as I am sure some of the others are well-versed in the evo-side of things and can and will bring up points you would have as well. Thank you, but I believe I'll continue to post my points as I concieve them, and not rely on others to communicate haphazardly the things I believe I'm best equipped to say. I've never expected Faith to reply, but despite continuous assertions that she "isn't interested in talking to me", she continues to address posts to me. And if she insists on lowering a previously-civil thread to a personal level as she did, I'll respond in kind, as I have. I've never demanded that Faith reply to my posts. She's never been forced to. If she doesn't want to talk to me, that's fine. But if she is going to reply its her obligation to be civil about it.
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DBlevins Member (Idle past 3798 days) Posts: 652 From: Puyallup, WA. Joined: |
I hope you don't feel like you are being piled upon by me. I just want you to understand that selection does not ALWAYS reduce variation. If you read through my post here and hopefully read the link I provided you would see what I am talking about.
Point is that when they are selected and reproductively isolated they generate a new race or breed or what evolutionists now call a species, and the very process of selection is the reduction of genetic diversity available to them. Natural selection does NOT ALWAYS cause a reduction in variation because hidden variation is ALWAYS present in continuously varrying traits. Natural selection can INCREASE variation. Here is example of how this can come about. Suppose you have an environment that favors larger beaks in birds. We'll let + equal the gene for large beaks and - as the gene for small beaks. Because deeper beaks is determined by genes at many loci, a population of even large beaked birds + have some small beak genes -. Now when the birds with the smallest beaks die, alleles for the small beaks are removed from the breeding popuation. This may increase the frequency of the + gene at every loci, but because even the larger beaked birds have some - alleles, variation still remains. Reproduction shuffles these genes within the population and because + genes are more common, individuals in future generations will have more + alleles. Because the more + genes you have the deeper your beak, the population will show a shift to larger beaks, and the new generations biggest beaks will be bigger than the previous generation. If this continues the same thing happens again. The individuals with the biggest beaks will have beaks even larger than the previous generation. As you can see you have MORE variation. This process can even be reversed. There is no genetic reduction, or reduced allotment of alleles, as if they are somehow reduced. Instead there is a shift in the frequency of alleles by selection working on the expressed alleles. This may or may not cause a reduction in the "FREQUENCY" of an allele, but that is because the frequency of a selected allele is increased. So if we see in our finches with small beaks that they are selected against, we still have a population of larger beaked birds that may have the small beak alleles. In the case of a drastic reduction, such as a bottleneck the allele frequency may shift so much that the allele for small beaks doesn't exist in the population, but the number of alleles for that trait are still there, they may all be large beak alleles. Now if some selection pressure caused the smallest beaked birds to die off you still have - genes in all but the largest beaked birds. There was no "reduction" in the alleles that affect beak size but a reduction in the FREQUENCY of the - allele. This I think is the misperception you have about some reduction. An example I have seen used is an experiment on oil content within seeds. The experiment conducted on corn showed that oil content could be increased, after 80 generations, beyond the initial oil content of 4-6%. The researchers were also able to reverse the process and select for low oil content instead. This showed that selection could INCREASE the initial range of variation.(From Boyd and Silk, ibid, p. 74 with the citing found in the url below) Evolution: Online course
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
And if she insists on lowering a previously-civil thread to a personal level as she did, I'll respond in kind, as I have. I've never demanded that Faith reply to my posts. She's never been forced to. If she doesn't want to talk to me, that's fine. But if she is going to reply its her obligation to be civil about it. = YOu keep saying this but I have no idea how I was uncivil. I asked you to make an effort to get what I'm saying as it seems to me all you were doing was objecting and objecting and correcting and correcting and taking the topic everywhere except what I was focused on, never made the slightest concession to anything I'd said, and that gets very wearing and I finally said so. The only incivility in the whole exchange came from you. This message has been edited by Faith, 11-29-2005 05:10 PM
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
Since the explanations are "simplified, digested and made easy" for my sake, yet are way too much for me to digest in a reading or in some cases ever, due to my ignorance, certainly; and since it is all so clear and simple to you, I wonder if you would be so kind as to explain to me briefly in your own words exactly what my opponents have collectively been saying to me over the last, oh, 60 to 70 posts. I'm sure it would be an immense help. Thanks Nosy. Appreciate it.
This message has been edited by Faith, 11-29-2005 05:20 PM
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
This stuff takes careful thinking and with twenty to thirty other posts that also take careful thinking I don't have time for it.
All I can say back to you at this point is that I haven't claimed that ALL the processes of evolution ALWAYS reduce genetic diversity. At least I've tried to remember to acknowledge that they don't. This message has been edited by Faith, 11-29-2005 05:32 PM
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crashfrog Member (Idle past 1489 days) Posts: 19762 From: Silver Spring, MD Joined: |
I asked you to make an effort to get what I'm saying And you consider that a feature of civil dialogue? You're hopeless. Almost every thread where I engage with you winds up in the same place - you're unable to defend your arguments, so you attack me personally. I keep your best example of your personal vitriol against me on a bookmark; it's hilarious.
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mark24 Member (Idle past 5217 days) Posts: 3857 From: UK Joined: |
Faith,
All I can say back to you at this point is that I haven't claimed that ALL the processes of evolution ALWAYS reduce genetic diversity. At least I've tried to remember to acknowledge that they don't. How could you, one of those processes does nothing but increase genetic diversity, & it happens with every individual with every generation. Mark There are 10 kinds of people in this world; those that understand binary, & those that don't
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
How could you, one of those processes does nothing but increase genetic diversity, & it happens with every individual with every generation. I've noted mutation as an exception in just about every post. But I haven't yet seen that mutation confers anything like a genuine useful trait.
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Mammuthus Member (Idle past 6497 days) Posts: 3085 From: Munich, Germany Joined: |
quote: These are not technicalities. Suppressed in terms of dominant and recessive traits is incorrect and completely confusing terminology when then applied to speciation. Suppression has its own definition. The point is, sometimes during the formation of populations there is a reduction in overall genetic diversity of the population. Sometimes there is an increase i.e. hybridization, sometimes there is no change, i.e. sympatric speciation. Sometimes there is isolation of populations and no speciation. It is also wrong to say it is a reduction in the variation available to them..once you are born, that is all the variation you personally are going to get. As soon as reproduction occurs, new variants are produced by mutation that happens every step of the way.
quote: I am sorry you feel that way. I have been reducing my explanations to a level I would use with high school students..and they usually get it. I am not trying to bury you in terms or technicalities. You might want to point out what it is you precisely don't understand from my posts. You have thus far made assertions about genetic diversity, genetics, and mutation that are false. When I explain it to you, you claim either that is over your head or I am burying you in technicalities but then proceed to claim you assertions are true. If I berated you (I don't believe I did) it is for making incorrect assertions and then claiming you are right while admitting you don't really understand the science.
quote:I don't disagree with you. However, you then sometimes switch to making it a general case which is wrong. I was also trying to correct you more on your misconceptions about mutation and genetics as opposed to speciation. Your paragraph about a general trend of reduction DURING speciation often holds true...especially for domestic breeding where selection is very intense. My only point is that this is not the only situation found in nature and may not be the most common. quote:I'm sorry that you feel it is conjectural but it is all established fact from the discovery of the DNA, the double helix, DNA polymerases and the study of their mutation rates. The direct genetic analysis of mutation events and their spread from parents to offspring and the segregation of mutations in populations. None of this is conjectural but is mundane lab work. quote:My only arguement with you here is whether or not it is the majority of cases. I do not see evidence for this. quote: I can see why you would think this but bear with me, it is a bit complicated. In addition to base pair change mutations, during every meiosis (when you produce the half of the genes that you contribute to your offspring and your husband his half) recombination occurs and shuffles your chromosomes. Thus, if you have different alleles at a given gene on each chromosome, you randomize them somewhat in transferring them to your baby. If there is selection at one locus that prevents a certain allele from being passed on, it will have no affect at other loci farther away from it because they recombine and randomly transfer one or the other allele to the next generation. Thus, you could reduce diversity at one part of a chromosome (in a population) but still be overall more diverse everywhere else for the rest of the genome..so the trend would only apply to one locus but not overall. That was probably to complicated?
quote: I'll try to break it down. A single population over time produces more and more variants due to mutation. In effect, every individual born is a novel variant. However, if the the population remains a single population and genes flow freely across the population (meaning there is nothing stopping an individual in one part of the population from breeding with another) they will stay a single species. This rule is broken in what is called sympatric speciation. In a large population with a complex environment (that is where cichlids come in), some individuals may become specialized by chance for a certain part of the environment that others are not specialized for. If there is selection for this specialization, over time, they may stop breeding with the general population even though they are in contact. Over time they cannot breed with the rest of the population and have speciated. This happens a lot in cichlids and has been observed in other species as well. African elephants (another one of my examples) is slightly different. Forest elephants are just that, a group of elephants that live in the forests of several countries in Africa. They are morphologically slightly smaller than the savannah elephants. They can breed with each other (forest and savannah). But the populations are genetically distinct and the limited breeding happens only where the two groups occassionally meet at the periphery of forests. But it does not diffuse forest genes into savannah elephants or savannah genes into forest elephants. So, although they can breed, they don't and the gene pools are very distinct. There are examples of this in baboons, crickets and lots of other species. Asian elephants are very different from African elephants. I promise you that if you look at them together, you will in about 5 seconds be able to tell which is which. They can also produce offspring when mated (it happened once) in a zoo though the calve died after 10 days. The gene pools of African and Asian elephants are as distinct as human and chimpanzee. Manatees are the most similar living species genetically to elephants. They don't look grossly similar and they cannot produce offspring. They do not inhabit similar environments. In each one of the cases I outline above, you have constant production of variants i.e. after speciation, the species does not stand still..it continues to vary with the birth of each individual. At different levels of separation, you get more and more restriction of gene flow whether it be restriction between different cichlid specialists, different types of elephants or different species entirely. At some point, there is no possibility for two populations to interbreed because they have become (and continue to become) so different from each other i.e. a elephants and manatees. The process of mutation, selection, drift, migration, etc. is the same in EACH case. It does not matter if you are looking at a population, a sub-species, species, genus, phylum, kindgom...the underlying process is identical. This is mick's point.
quote: Not exactly correct. Think of it this way. You pack your suitcase with 1/10 of your clothes at random and fly to China. the other 9/10ths are not eliminated..but they are not in China. This has nothing to do with selection however. This would be called a founder event. Traits are not selected by population isolation. This is genetic drift. The random sub sampling of a larger population. If a small population moves into a new environment, they may come under new selection pressures. Take my forest elephant example. The Savannah elephants are enormous. They are bigger than woolly mammoths were. They are adapted to eating grass and living on open plains. Forest elephants are in a different environment entirely and due to selection, have some special adaptations for it. Most obvious, their size is greatly reduced compared to Savannah elephants since living in a forest restricts you overall size so the larger elephants of the original population would have been eliminated. Take it a step further out to mammoths. They lived on the arctic tundra. Their ears got small, so they would not lose heat, compared to African elephants that have huge ears. All newborn elephants are covered with hair..particularly Asian elephants...mammoths grew a thick covering of hair to protect them from the cold. All of this is because the new envirnoments they encountered would have applied very different selective pressures on the different populations once they separated. Over time, only the offspring that were best adapted would have survived to pass on their genes. Over time, this made the species very distinct from one another. Mick's chipmunks are showing the same thing. These are only a few examples out of thousands. The principles are always the same.
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
The point is, sometimes during the formation of populations there is a reduction in overall genetic diversity of the population. Sometimes there is an increase i.e. hybridization, sometimes there is no change, i.e. sympatric speciation. Sometimes there is isolation of populations and no speciation. It is also wrong to say it is a reduction in the variation available to them. I'm thinking along lines of a TREND, an overall reduction of genetic diversity throughout all populations or all life forms over all time. I know that in any particular formation of one population from another this may not occur, but the idea is to see if overall it occurs, as it seems to me it does. These processes either reduce genetic diversity or they more or less maintain the status quo, they don't increase it. Seems to me that the ONLY thing that increases genetic diversity is mutation. In the creationist way of thinking, hybridization doesn't add anything, it merely recombines parts of what is already the genetic allotment of a Kind. Thinking evolutionistically, mutation is continually adding genetic material -- but not everybody talks about it as a normal predictably beneficial process as you do. Your high school students are just trying to absorb what you are teaching. I am trying to find out what's wrong with it. That is, I'm trying to think through things that you already have answers for, and think about them from a creationist point of view which contradicts your point of view. I think that may make it a bit more difficult for me to learn the official terms. Or it is a personal flaw, as it seems I learn them only to lose them. Something to do with my age perhaps. In any case, correct term or not, Mick knew what I meant by the word "suppression" and I'm sorry I can't communicate with you that easily. I have had less time to think about all this in the last few days, a situation which will continue for a few more days, and what there is to think about is more than usual, so I'm lagging behind, but I wanted to answer that much of your post.
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Mammuthus Member (Idle past 6497 days) Posts: 3085 From: Munich, Germany Joined: |
quote: In the interest of time, I will keep this response short. There is certainly not a trend of overall reduced genetic diversity. In some species there is..especially those that are threatened with extinction. In humans, our diversity is increasing and their are lots of studies that show this. In many other species this is also the case. There is simply no "genetic allotment". That concept can be easily refuted, and has. In fact, you and I probably have entire pieces of DNA that differ from each other and are entirely new due to a phenomenon known as retrotransposition. However, I will point out one thing that may not have been clear, I don't mean to indicate that every mutation is successful. There are mutants that are born sterile or otherwise unable to reproduce that basically become extinct. Mutation is countered by selection. The vast majority of mutations wind up as miscarriages. I was not trying to insult you with the high school comment. I am just indicating I am watering down the technical jargon a great deal. My only way to know what you do understand or don't is by you pointing it out specifically. You will have to keep in mind that I am not used to talking about genetics with non-biologists. I am used to talking about it with other molecular biologists...so we basically have to teach each other how to communicate with each other
quote: Take all the time you need Faith. The advantage of a forum like this is that the post won't disappear and you don't need to answer in haste. Cheers,M
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Faith  Suspended Member (Idle past 1466 days) Posts: 35298 From: Nevada, USA Joined: |
In the interest of time, I will keep this response short. There is certainly not a trend of overall reduced genetic diversity. In some species there is..especially those that are threatened with extinction. In humans, our diversity is increasing and their are lots of studies that show this. Hybridization, sexual recombination etc. Not a genuine increase according to a creationist, simply a way the trend to reduction is masked in a large gene pool. According to my conjectures, it is in species that are threatened with extinction where this trend of genetic reduction reaches its final extreme, that's why it is noted at that point, and those extremes do tend to be where "speciation" has recently occurred, no? In any case, I am convinced those extremes prove the overall trend, "the way of all flesh" as it were. I am certain there is a genetic allotment so your flat assertion that it's been disproved doesn't deter me. It is a terrible handicap to have no experience of talking biology with a nonbiologist. I don't know if it's possible to overcome that. I don't know if I could anticipate a communication problem soon enough to correct it, but maybe you could have in mind that if I'm using a scientific-sounding term that doesn't sound right to you, perhaps I'm using it in a nonscientific way. That might help. Thanks for the acknowledgment that most mutations are unsuccessful. How sure are you that that leaves enough useful ones to counteract the genetic reduction effects of selection, migration, bottleneck and so on? What kind of data/statistics could even be available about this? Thanks for keeping your post short. This message has been edited by Faith, 11-30-2005 11:26 AM This message has been edited by Faith, 11-30-2005 11:29 AM
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