The End of Evolution By Means of Natural Selection

No, you didn't.I am very sorry if anyone thought I was imputing any such thing. I edited the article myself --- after you quoted it. I had thought that that would have been obvious ...I was trying to make a point (which I thought was funny) about the use of Wikipedia as a gold standard.Once again, I apologize if this confused anyone.

Hi Percy, No, I meant alleles, as this is how you get variation in species, and varieties exhibit variation, but are still genetically compatible with other varieties. Varieties can - and frequently do - interbreed (see hybrid zones as one example).Varieties are cause by a shift in the frequency of alleles (hereditary traits) in populations in isolation from other populations, but can be reabsorbed into the parent population if conditions warrant.While this normally occurs, according to biological science and various field studies, with the modification of existing alleles by mutations, this is not necessary.The peppered moths (Peppered Moths and Natural Selection) are an excellent example of no genetic change, but a shift in the frequency distribution of alleles from one generation to the next, resulting in a shift between which variety of moth is most prevalent:

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Note first off that this article refers to the two varieties of the moth:

• Biston betularia typica (the light color version) and
• Biston betularia carbonaria (the dark color version)

In the scientific name structure (for those unfamiliar with it) we have family (Biston) species (betularia) and variety (typica or carbonaria) designations.

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An important distinction is made between 'species' and 'variety' and that is that 'varieties' can interbreed: when the genetic difference is great enough that no viable offspring are created then we would then have a different 'species' - this is the scientific distinction. As we are not talking about species differentiation at this point in this scenario, the speciation part of the theory of evolution is not tested, per se.

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From BIOLOGY by Miller & Levine, page 298:

"Kettlewell found that in unpolluted areas, more of his light-colored moths had survived. In soot-blacked areas, more of the dark-colored moths had survived. Thus Kettlewell showed that in each environment the moths that were better camoflaged had the higher survival rate. It was logical to conclude that when soot darkened the tree trunks in the area, natural selection caused the dark-colored moths to become more common. Today Kettlewell's work is considered to be a classic demonstration of natural selection in action."

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Sometimes classification is difficult if the populations are isolated. It is frustrating as a birder to see classifications change from different species to different varieties of the same species and back to different species, depending on the authorities and the latest cladistic information. I resolve this by tracking both species and variety when possible, in order to adjust as the new information comes out.Of course the bird species of special interest to me on this topic is the asian greenish warbler, Phylloscopus trochiloides, as noted in Message 260:

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The existence of the hybrid zones between each variety in the Greenish Warblers is evidence that hybrids only occur in these zones, AND that they can be (and are) identified as hybrids by having a mixture of traits\alleles present in one or the other neighboring variety population zone, but not common to both neighboring variety population zones. Instead we see:

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1. P.t.viridanus
   
2. a hybrid zone between P.t.viridanus & P.t.ludlowi
   
3. P.t.ludlowi
   
4. a hybrid zone between P.t.ludlowi & P.t.trochiloides
   
5. P.t.trochiloides
   
6. a hybrid zone between P.t.trochiloides & P.t.obscuratus
   
7. P.t.obscuratus
   
8. a hybrid zone between P.t.obscuratus & P.t.plumbeitarsus
   
9. P.t.plumbeitarsus

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This means we have a condition where there is sufficient reproductive isolation for the varieties to exist as independent populations, only mixing with other varieties through the hybrid zones, and that poorly at best.Of course evolution with natural selection, genetic drift AND mutation is fully capable of explaining these populations.It is Faiths hypothesis of allele loss with no new alleles that I have trouble with for explaining all the evidence.I have little doubt that once we get a formal formulation of the Faith Hypothesis, with an accurate description of how it operates within a population, a formulation succinct and explicit enough that predictions can be made, that there will be instances that fit the description. What I have trouble with is extending this to all populations all the time.Enjoy.

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Yes, I also thought that was funny. I guess my irony detector was functioning properly.I wasn't sure whether you had done the editing, or had noticed that it had been edited. Not that it much mattered which.

Thanks for the apology.I noticed the remark about the gold standard and that was a clue that you'd probably edited the page, but hey, everybody uses Wikipedia -- it's the easiest source of a ton of information about just about everything, and generally people who write there do know their subject or they wouldn't be doing it, AND if you have an objection to something said there how about just saying that and giving your view?

Hi RAZD,I appreciate that you must have taken a great deal of time and care to write such a detailed reply, but it's way too long. This is a minor misunderstanding at worst, it should take only a single paragraph at most to clarify.So I'm afraid I can't reply to what you said because I didn't read it. I'll just say that as long as both populations still have strict subsets of the alleles of the original parent population then they must, on a genetic basis, still be the same species. As I've said to Faith, there may arise physical or behavioral differences that prevent mating, but both populations would remain genetically compatible.--Percy

Have to say I disagree with you here Percy. Within a normal breeding population you are likely to have a spectrum of genetic reproductive compatibility. Given such a situation I can quite readily see a situation where you could produce two daughter populations with distinct strict subsets of the alleles from the parent population but which are not genetically compatible. The loss of alleles or genotypes from the parent population that allowed gene flow between these sub-populations could effectively ensure their reproductive isolation.Suppose there is a gene Fertile with alleles Fertile^a and Fertile^A in the original population. Homozygotes of either allele can breed with each other and with heterozygotes but neither can produce viable fertile offspring with each other. If this population is split and due to drift the Fertile^a and Fertile^A alleles are fixed in respective populations then we will have established 2 genetically incompatible populations without any further mutations, only through loss of one allele from each population. If we reintroduce the 2 new populations to each other they would not be able to breed.Off the top of my head I don't know of any examples such as this, but I don't see why it couldn't happen, or how we would not have to consider the resulting sub-populations distinct species.Given a wide enough panel of genes with alleles giving rise to hybrid inviability we might even see a situation like the Greenish Warbler ring species arising through such a reductive form of speciation.I think RAZD's distinction was that you can't get a genetically reproductively isolated population if another population still exists which retains all the parent populations allelic diversity. In other words, if either of my two Fertile^a/a and Fertile^A/A sub populations were reintroduced to the parent population which still had Fertile^A/a individuals and those of their own genotype in it then they could introgress.TTFN,WK

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So I'm afraid I can't reply to what you said because I didn't read it. I'll just say that as long as both populations still have strict subsets of the alleles of the original parent population then they must, on a genetic basis, still be the same species. As I've said to Faith, there may arise physical or behavioral differences that prevent mating, but both populations would remain genetically compatible.

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Percy,physical and behavioural differences that prevent reproduction of one group with another are sufficient to make them into different species, aren't they?I've been thinking about this in the context of dogs. I suspect (though I don't know) that the massive size variation in dogs is brought about by assortment of alleles rather than mutations. The biggest dogs and the smallest dogs are reproductively isolated from each other - they cannot mate and the small dogs could not bring a mixed puppy to term. Something similar in the wild would generate multiple species.Now, if there were a population with a continuum of sizes, then this issue wouldn't arise. But if the 'middle size' population were to disappear, it definitely would.Edited by Peepul, : No reason given.

I've said the same thing myself, but in terms I thought Faith could understand. General principles first, less common cases next, rare cases after that, unusual exceptions last. Precision and completeness are not compatible with simplicity, and I think simplicity must take precedence with Faith because every detail is another detour of distraction.I agree that there must be cases out there of breeding populations with individuals that are infertile with one another, but I think carefully crossing t's and dotting i's at this level of detail can only be confusing at this point. Faith throws in terminology that would normally be indicative of a person who can handle the detail, but she's just throwing around words she doesn't understand. She doesn't understand much of what reads both here and elsewhere. A great recent example is when she stated that she thought we'd been saying that mutations don't change the basic genomic structure of species. How basic a misunderstanding is that!Science proponents often bemoan science writing that simplifies for the layperson to the point of being wrong, so I'm aware of the dangers. So when you say this: I have no argument with it, but I don't believe it is possible to have a successful discussion with Faith at this level of detail before getting across the simple principles. Getting into the details of uncommon ways that reproductive isolation can happen works against this.--Percy

It depends upon how you define species. I defined it genetically at the same time that I noted the potentially isolating effects of physical and behavioral differences.--Percy

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It depends upon how you define species. I defined it genetically at the same time that I noted the potentially isolating effects of physical and behavioral differences.

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If you define it genetically, then you are right apart from the kind of genetic incompatibility WK was talking about. But I think that makes the problem easier! It would be better to refute Faith's argument using the 'interbreeding populations' definition of species. Although there is no formal agreement to it, that's the most commonly used definition.Edited by Peepul, : No reason given.

This is the definition Faith is using, and if you don't peer under the hood at the genetic underpinning of the phenotypes then you'd might conclude she's right. But closely related populations differ not only in the alleles for each gene, but also in terms of which genes they have and even which chromosomes they have. I think examples of closely related populations where the differences are in allele subsets only are rare. Even WK couldn't think of any examples.--Percy

Hmm, the problem here is that Faith's initial assumption mean we should treat all alleles/ gene variants as if they were part of the hypothetical parental populations complement, unless we can definitively demonstrate a mutational origin for the allele. In most cases we don't have an original parental population to compare to, only two daughter populations. If we accept Faith's framework all of these differences are only those of allele subsets of the original parental population.There are many examples of genes that have been identified as the bases of hybrid sterility and inviability but showing that the origin of those genes was mutational is not possible in the absence of an original parent population, and even with one would require exhaustive genotyping to be certain that the allele was not present anywhere in the original population.TTFN,WK

Granted that Faith's view is theoretically possible it still seems unlikely to me to be the case every time. And don't her Flood beliefs make it even more unlikely ? If you take the standard YEC view of the Ark carrying representatives of Creationist "kinds", each of which produced a number of species, all these alleles must be carried in a single breeding pair, in many cases. Obviously that pair must successfully interbreed, and it wouldn't be good if their offspring suffered interfertility problems. And yet, somehow we must get - from a single pair - multiple populations incapable of interbreeding. Without mutation playing a role at all ? Does this sound plausible to anyone ?

Hi Percy,The first paragraph was your answer, the rest is just explanation for it.Essentially, I see no reason that some cases exist where separate varieties become isolated with different sets of alleles through loss.The problem is that they were interfertile before and that if they have no had any mutations, changes to the genetics, that there is no reason for interfertility to be lost. The only possibility is graded fertility originally, possibly hidden due to the number of other mating possibilities, as Wounded King suggests, however the lack of evidence for\against this as a pre-existing condition in original populations is a problem either way.PaulK has his finger on another problem with the Faith Hypothesis: it is not possible for a single organism to carry all the alleles in existence today, they can only carry two at a time. You need an original population to carry all the alleles.Enjoy.

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I am speechless, but fortunately it is not necessary for me to say anything in order to mock you. Your own statements are quite sufficient.