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Author | Topic: the phylogeographic challenge to creationism | |||||||||||||||||||
crashfrog Member (Idle past 1495 days) Posts: 19762 From: Silver Spring, MD Joined: |
Come on, crashie, you simply need to REALLY prove it SO carefully to li'l 'ol ignorant me. Surely you know that it takes much repetition and careful explanation and many different approaches to educate a person in the complexities of genetics. If it ever seemed like you were capable of absorbing the information, or were interested in doing so, I might. As it is it's not so much a matter of "patience" as it is me getting tired of bashing my head against the same brick wall. Some people are too old to be taught, I suspect.
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crashfrog Member (Idle past 1495 days) Posts: 19762 From: Silver Spring, MD Joined: |
It's when there is very little diversity left that the phenomenon I'm talking about is on display as it were. At this point we have speciation to the max. I don't understand what you mean here. "Speciation to the max"? Doesn't make any sense. If you have a population with no diversity, then you have one species. Not speciation to the max, which would be every individual in the population being their own species. "Speciation" is when a population gives rise to a subpopulation of a new species. It's not a condition of genetic diversity, and a lack of genetic diversity doesn't cause it. It's a condition of gene flow that, often, results in decreased genetic diversity for both populations, because they each lose access to the distant genes of the other population. For instance, if you were to take the state of Alabama and send all the white people here and all the black people there, each of those new populations would be less diverse than the population they were when they were joined; but if you were to populate a new state with nothing but identical clones of a single individual (no genetic diversity at all), that would not be "speciation" of any kind.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
"Speciation" is when a population gives rise to a subpopulation of a new species. It's not a condition of genetic diversity, and a lack of genetic diversity doesn't cause it. The same factors that lead to speciation lead to the lack of genetic diversity. These are the processes that divide populations and aplit them apart. If there is a causal relationship it is in the other direction - a reduction in genetic diversity is usually what has to happen to develop a new trait in a population.
It's a condition of gene flow that, often, results in decreased genetic diversity for both populations, because they each lose access to the distant genes of the other population. Which is exactly what I've been talking about for months, exactly the result of all the processes that divide populations. They all lead to a reduction in genetic diversity for the reasons you are talking about. If you didn't get that this is what I was talking about, no wonder nothing you've been saying has made any sense.
For instance, if you were to take the state of Alabama and send all the white people here and all the black people there, each of those new populations would be less diverse than the population they were when they were joined; Gee, he finally gets it.
but if you were to populate a new state with nothing but identical clones of a single individual (no genetic diversity at all), that would not be "speciation" of any kind. Depends. Often something similar is exactly what gets called speciation, only less dramatic than the extreme of a clone.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
Here's a question for the expert as this thread winds to an end.
So in the case of say the cheetah, or any creature which has been reduced to homozygosity at many loci, this has come about through the removal of alleles from the population by one process or event or another such as migration or natural selection or the like, right? The cheetah's having suffered the severest kind of bottleneck, even reduction to a single female, is the usual explanation in that case I believe. But there may be many degrees of removal of alleles from a population by these same processes, depending on the genetic potentials in the original or any given parent population, and the severity of the population reduction, so that it could take many such processes to affect the genetic diversity appreciably, so that a state of stability or equilibrium could be the case for many generations. Or on the contrary only one migration, certainly a bottleneck, could even remove half a dozen possibilities for one loci from the population, or more or less, but that in any case through many splittings over many years or centuries, and leaving mutation aside for the moment, we are talking about a progressive reduction in genetic diversity in each of the new populations from the old. And this may at times involve such changes as amount to speciation, so that a new population may in fact diverge so appreciably from the original or even the previous parent population that we have what is called a new species. Isn't this what Mick was describing in his OP? Am I also right that simple death of individual immature (nonreproducing) organisms over long periods of time would also contribute to the overall reduction of genetic diversity in ALL populations as surely alleles are removed from the population by this means too, though much more gradually than population splits or massive numbers of deaths would bring it about of course. Further, doesn't this progressive gradual depletion imply a previously much much greater genetic diversity in an original population back oh a few thousand years or so? And, what kind of further change may occur at a particular locus after it has been reduced to homozygosity in a given population? What if a bad mutation simply wipes out that allele in an individual rather than producing a viable chemical alternative? I assume this could happen and if it is not lethal to the creature it would be passed on, this complete absence of an allele or a whole locus, no? If other factors favored this particular strain, even perhaps by some toxic agent's being foiled by the absence itself, this complete absence of a gene could even come to dominate in a population, couldn't it? What would this dead locus look like in the genome? Might it look like junk DNA? Yes, I understand that mutation supposedly counteracts the processes of reduction and removal of alleles from populations, but as usual I would like to focus on these processes apart from it if you would. This message has been edited by Faith, 12-20-2005 03:44 AM
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crashfrog Member (Idle past 1495 days) Posts: 19762 From: Silver Spring, MD Joined: |
If there is a causal relationship it is in the other direction - a reduction in genetic diversity is usually what has to happen to develop a new trait in a population. No, mutation - increase in diversity - is the source of new traits. We've already established that your position is nonsense; it's ridiculous to assert that new traits in a population connote reduced diversity, since diversity by definition is a measure of how many different kinds of traits exist in a population. New ones mean, by definition, that diversity has increased. Speciation is not the same as new traits. You conflate the two but you do so in error. Speciation means new species, not new traits. New species tend to develop new traits, of course, but that's a function of rebounding diversity after the speciation event. As I said, this is going to be very difficult indeed if you're completely unwilling to correct your mistakes. By definition, new traits cannot connote a reduction in diversity. Since they are new, diversity must have increased.
Which is exactly what I've been talking about for months, exactly the result of all the processes that divide populations. They all lead to a reduction in genetic diversity for the reasons you are talking about. No one's challenged this. I'm agreeing with you. It's you who doesn't seem to understand that.
If you didn't get that this is what I was talking about, no wonder nothing you've been saying has made any sense. What hasn't made sense? Did it occur to you that you could ask me questions, ask me to clarify? It would certainly be much more prudent if you actually made an effort to comprehend the information I'm presenting to you, before you summarily dismiss it.
Often something similar is exactly what gets called speciation, only less dramatic than the extreme of a clone. Right, but it wouldn't be "speciation to the max", it would be one single instance of speciation. I don't consider "one" to be "the max", so it's still not clear to me what you meant by "speciation to the max." Somehow I doubt it's even clear to you.
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crashfrog Member (Idle past 1495 days) Posts: 19762 From: Silver Spring, MD Joined: |
What would this dead locus look like in the genome? Might it look like junk DNA? We call them "pseudogenes", actually. For instance, the broken gene in primates, including humans, for the synthesis of ascorbic acid (Vitamin C).
Yes, I understand that mutation supposedly counteracts the processes of reduction and removal of alleles from populations, but as usual I would like to focus on these processes apart from it if you would. I don't see that that's necessary, since you already seem to have a handle on these population-level processes. It's the genetic-level processes of mutation and heredity that you need help on. And considering them apart from each other doesn't give you the whole picture. It's like saying "I know that a house has walls and a roof, but I want to consider houses seperate from roofs for a moment. Wouldn't you say that, when it rains, the walls of your house aren't going to keep you from getting wet? And aren't houses therefore useless in the rain?" Well, yes. If houses didn't have roofs, your conclusion would be correct. The same with your conclusions about reducing genetic diversity in populations. But houses generally do have roofs, and mutation is a universal condition in genetics. Your conclusions would be just about accurate, but only if you ignore about half of the picture. It's not clear to me why you think that's useful.
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nwr Member Posts: 6412 From: Geneva, Illinois Joined: Member Rating: 4.5 |
I said I would respond in detail to your post. However, I see that others have, and that this thread is fast approaching the 300 mark that will end it.
Sometime in the next few days I may try opening a new thread where I can comment on some of the issues you raise. It won't be a continuation of the current thread, but it will address questions of biological diversity.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
Crash, I'm sure you've said some useful things somewhere in all your attempts to educate me, but I don't relate to your way of expressing youself or relating to me and it ends up being counterproductive, so until further notice I will refrain from addressing your posts, and please don't answer my posts on this subject. I would really appreciate it. Thanks.
This message has been edited by Faith, 12-20-2005 11:26 AM
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crashfrog Member (Idle past 1495 days) Posts: 19762 From: Silver Spring, MD Joined: |
so until further notice I will refrain from addressing your posts, and please don't answer my posts on this subject. Mmm... no. You're under no obligation to answer, of course, but I believe that I will continue to reply to any post of yours that I see fit. If you truly wish to be untroubled by reading what I have to say, then by all means, restrict yourself to the Faith and Belief forum. Trust me, it's rare that I get into that snoozefest.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
I said I would respond in detail to your post. However, I see that others have, and that this thread is fast approaching the 300 mark that will end it. Sometime in the next few days I may try opening a new thread where I can comment on some of the issues you raise. It won't be a continuation of the current thread, but it will address questions of biological diversity. It won't interest me if it doesn't acknowledge the point I've been trying to make here. If it does, and you want to discuss how mutation alters that picture, that could be interesting.
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REALIST Inactive Member |
edit//.com is a good place to start for the non-believers in here.
make the right choice in this life, as there are no second chances in the next. even if you don't choose, the default is still hell, as the evidence of God is glaringly obvious everywhere we look. This message has been edited by AdminPhat, 12-21-2005 02:03 AM
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arachnophilia Member (Idle past 1372 days) Posts: 9069 From: god's waiting room Joined: |
well, you're off to a good start. bare link, spamming, preaching, judgement, fire and brimstone, off-topicness and bare assertions, all in the span of two sentances of a first post!
what would jesus say? "welcome to evc." This message has been edited by arachnophilia, 12-21-2005 03:45 AM
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AdminPhat Inactive Member |
REALIST, Welcome to EvC. We DO have certain rules around here, one of which is that you cannot simply join a topic and begin spamming your beliefs.
Please read our forum guidelines, rules, and procedures.
Comments on moderation procedures (or wish to respond to admin messages)? - Go to: New Members: to get an understanding of what makes great posts, check out: This message has been edited by AdminPhat, 12-21-2005 02:08 AM
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