the phylogeographic challenge to creationism

I agree Robin. I read through the OP, and it is impressively thorough and thoughtful, but I fail to grasp how it is in any way a challenge to creationism.I've avoided this thread because I'm afraid it would just bury me in a morass of semantic distinctions, but I guess I'll risk saying this much.

How does the OP demonstrate that micro and macro evolution are just gradations of the same process? It is merely a description of the effects of isolating portions of a population which is hardly unknown to creationists. It is what happens in the development of races of human beings too. That is, subgroups of a population take a portion of the gene pool with them, reducing their genetic variability in relation to the parent population, and this develops distinctions in the group from the parent group and from other isolated groups.This occurs in all the forms of "evolutionary processes." It occurs in natural selection and it occurs in artificial selection (breeding), it occurs for geographic reasons and it occurs for behavioral reasons etc. etc. etc. It occurs wherever a part of a gene pool is isolated reproductively from the larger gene pool, in any way whatever and for any reason whatever, by removing some genetic potentials and bringing new genetic combinations to phenotypic expression that were suppressed in the parent population with its greater genetic variability.This message has been edited by Faith, 11-25-2005 08:20 PM

Thanks, Mick, I appreciate very much that you didn't get hung up on my no doubt less than technically exact language, but simply understood what I was saying. I can't always get the right term matched with what I have in mind but I think I can make it reasonably clear if you can continue in this vein. Thank you. Quite clear. Again, nicely clear. Appreciate the description. Also nice to learn the terminology "migrant" and "ancestral" for these purposes. Thank you again. It helps to get the specifics laid out as you are doing. Yes, I often use untechnical language but yes indeed that is what I am thinking of. That's how you could get a blue-eyed migrant population of human beings out of a dark-eyed ancestral population.Overall a very informative post.This message has been edited by Faith, 12-01-2005 01:41 AM

Wonderful. I'm SO glad that was clear. Yes. But I have a problem with the term "species." But I know what you mean so I just want to mention it. Yes. Don't like that term "species" as I said. How about "subspecies" or "breeds" or "varieties?" Could, certainly. Problem with term "species." Diversification of varieties/breeds/subspecies certainly may be the result of all these processes. They are still Tamias. All species have always been known to vary. Domestic breeders have always produced varieties. The most striking variations are produced by the severest isolation and inbreeding, processes that involve less and less genetic diversity and hence less capacity to vary further without reintroducing the ancestral genes -- and in some cases extreme genetic specialization ("structure?") leads to inability to breed with other varieties of the species, leaving it even more out on a limb as far as future developments of the variety go. So as a principle or rule, overall the production of new phenotypes is accompanied by reduction in genetic diversity which is a trend away from evolutionary potential. I know there are exceptions.So in other words, the very genetic mechanisms that produce these variations in principle have a built-in limit. At its extreme that limit is reached in actuality by such a "species" as the cheetah whose genetic diversity is almost nil, and whose prospects of survival let alone capacity for further genetic diversity are severely compromised. To my mind this IS the natural barrier to evolution beyond the species. it is built in to the gene pool that it cannot vary beyond a certain point in any direction. I think there is a huge range of PHENOtypic change that can occur within one species and I don't think I could define it beyond saying that for instance among dogs you'd have to produce one that had none of the dogness of dogs left, and every breed of dog I know of is always characterized by dogness. Same with catness. To some extent I think these qualities can be specified objectively but I'm not sure how far.I think the evidence would have to be on the genetic level. I would have to see a genetic mechanism that truly and convincingly counteracts the above effect of the reduction of genetic diversity as a result of what is often considered to be "speciation." And not only counteracts but far outstrips it by multiplying genetic diversity to a luxuriant degree. Mutation is usually offered as this mechanism, but it looks to me to be a pretty anemic candidate.This message has been edited by Faith, 12-01-2005 01:47 AM

Well, I was giving the only criterion I could think of for a phenotypic change that would convince me of macroevolution, and if it's impossible it's impossible.Do we agree that most evolutionary processes (migration, bottleneck, founder effect, natural selection etc etc) do involve a reduction in population accompanied by a reduction in genetic diversity, to one degree or another? So we further agree that it is these processes that eventually produce the new "species" that are observed by biologists? If this is the case, it does seem to me that either these aren't evolutionary processes but devolutionary processes that define the limits of the Kind or Biblical version of a Species -- OR that evolutionists could demonstrate at the extremes of one of these trends a describable loss of the character of the species. Even dogness or catness as many times these animals have been bred out to a genetic limit or near limit which is where any such change according to evolutionary theory should begin to show up it seems to me. But selection if not always then usually leads to a reduction in genetic diversity despite any increase in information. How does this sort out in favor of macroevolution if each minuscule change through mutation only has a recognizable impact on the phenotype in a population with fewer genetic possibilities? You'd have to explain epigenetics to me.

Exactly what is it data-wise that is interpreted as a steady increase in genetic diversity for 10,000 years? I believe you told me once, sorry I have trouble keeping those things in mind. I have to comment, however, that if that is the case, poor cheetah. 10,000 years of an increasing chance at survival and its genetic situation is still about as severely limited as it ever gets. Well, I was answering the question if there is anything on the phenotypic level that I would take as evidence for macroevolution and that's all I could think of -- the loss of the recognizable character of the species. I said there may or may not be some objective way to define dogness or catness, that I wasn't sure how far that could go. It's just that it is very striking that no matter how bizarre and genetically compromised a breed of dogs you can get, and with dogs in particular they can get awfully far out, they all act like dogs. You can get types that look like anything from a small horse to a bear to a rodent to a muffin, but they all act like dogs. But that neat definition doesn't help me define what I'd regard as evidence for macroevolution. Inability to mate isn't that evidence for me.

DOGness.I don't know. I just know it when I see it. They all wag their tails, how about that for a start. But I don't CARE about this, so let's not get off on it. It was the only answer I could think of that could possibly convince me of macroevolution on the phenotypic level. But as I said, I don't think anything on that level would convince me as there is an enormous range possible.This message has been edited by Faith, 11-27-2005 02:28 PM

But only through mutation and I'm not at all convinced that confers any truly beneficial effect overall, certainly that it could do so at any rate that would produce macroevolution. Filling a niche does not affect the genetic picture, it merely expresses it, and selection is not ALWAYS coupled with mutation, and mutation is hardly a convincing mechanism for the kinds of change needed to overcome the effects of the selection processes that fitted the species to the niche, the reduction in genetic diversity that always defines that condition, let alone provide opportunities for further change beyond the niche. That's OK. In other words there is nothing at all that can be demonstrated phenotypically that would truly demonstrate macroevolution. I'm happy to drop the idea. It is simply the only thing that occurred to me that I would consider proof of macroevolution on the phenotypic level. Fecundity does not increase genetic diversity. You can have enormous numbers of a particular breed but the same reduced genetic potentials. Again, mutation appears to be the only hope for macroevolution.I think epigenetics is going to get me too far afield so I'll leave it alone for now, but thanks for the link.This message has been edited by Faith, 11-27-2005 02:41 PMThis message has been edited by Faith, 11-27-2005 02:45 PM

I don't know, jar. Haven't yet worked out the definition you know. It's obviously a dog on all the other characteristics one might think of for dogness. Perhaps we need a checklist. But its not having a tail doesn't mean it doesn't retain the behavioral component in some way. Does it wag its butt?

I'm not following you at all, I'm afraid, [AbE or perhaps I just can't entertain your evolutionist assumptions very far] and yes the dogness/catness idea was a throwaway I don't care to pursue.And I just about never use the term "macroevolution" as I think the whole idea is wrong, only use it when I'm afraid more confusion would result if I didn't.There is only built-in variation according to the genetic mechanisms within the Kind (a term that is used by creationists to avoid as much as possible the connotations evolutionists attach to the term "species").To restate it, this variation is limited, I've come to believe, by the observable fact that the more striking the phenotypic variation from the ancestral type, the more limited the genetic potentials and the genetic diversity in the new population, and therefore the less able to produce new types for further selection. And all this adds up to a REDUCTION in evolutionary potential rather than anything that could possibly further it.The only thing that is ever proposed to counter this trend is mutation, and I have yet to see anything about mutation that suggests it has even the remotest potential to produce enough viable genetic material to support much "micro" evolution against the de-volutionary trends I'm talking about, let alone "macro."What are called Evolutionary Processes in most intros to population genetics are in fact DEvolutionary Processes, as their trend is ultimately always toward less genetic potential, less genetic diversity, and at the extremes great vulnerability to various diseases and deformities and ultimately extinction.This message has been edited by Faith, 11-27-2005 07:14 PM

The reduction in genetic diversity that accompanies phenotypic variation is OBSERVED. It is KNOWN. The fact that migrated populations vary from the ancestral population via the reduction of genetic possibilities is KNOWN. Ordinary dominance-recessive patterns are OBSERVED to explain a great deal of it.You'd have to prove that all those mutations have the effects that are much more easily and naturally accounted for by these known mechanisms I am talking about. You'd have to prove they have always occurred at that rate also, and that they do produce beneficial results. In other words, referring to numbers of mutations and the mechanisms of forming proteins does not prove that any of it has anything to do with what Mick originally described on this thread, and he did not appeal to any of those processes either but described it all in terms of population genetics I could easily grasp. Your information simply adds obfuscation whether that is your intention or not.This message has been edited by Faith, 11-27-2005 08:15 PM

That helps. I guess I'd agree, if we had arrived at a good definition of the unique features of Catness and Dogness and a convincing combination could be demonstrated. But the two species don't go back to a common ancestor according to evolutionism in any case. The mechanism is the Evolutionary Processes themselves, the very processes that sort and select. The predictable reduction in genetic diversity is the mechanism. Not at all. The greater number of variations are due to the shuffling of ordinary Mendelian factors such as dominance and recessiveness. It's not hard at all. It's a very easy kind of idea. But genetics really doesn't support it. Variations don't exactly "build up." Whenever there is a variation in the phenotype there is a corresponding reduction in genetic diversity that allowed it to come to expression. They go together hand in hand, the reduction of genetic diversity and the production of a new phenotype. You don't get fancy breeds without the aggressive elimination of lots of genetic potentials, and the same thing happens in nature when you get a new type that is tightly designed to fit a niche and so on. It is only by eliminating other genetic possibilities that you get the new "species" and this being the case variation or "evolution" beyond the given genetic potentials of the original ancestral species is impossible. Darwin didn't know anything about genetic potential did he?Seems to me the more that is known about genetic variability the clearer this pattern is, that the reduction of variability corresponds with phenotypic change, and there has to be a natural limit to this process.This message has been edited by Faith, 11-27-2005 08:34 PM

Two.Nope, you didn't understand his question at all. He put it better himself.

There are Two. You have no notion of what a Kind is.

Mick understood and agreed. I think I'll stick to discussing it with him.