the phylogeographic challenge to creationism

Since you've used this example before, you should know that the genetic diversity of cheetah populations has been steadily increasing for about 10,000 years. That is, until recently, as they've been experiencing a marked reduction in population as a result of expanding human encroachment. I don't understand what "dogness" is. And species Platonism - the concept that you invoke in this paragraph - has been discredited for hundreds of years. An individual is not in a certain species because it has the "essence" or "nature" of that species; it's in that species because that's the population with which it can mate.This message has been edited by crashfrog, 11-27-2005 01:44 PM

Fossils, phylogenics, the like. The usual sources, basically. Well, that's the destructive power of humanity for you. Honestly, what can stand in our way? Well, what makes you think that such a thing as "species character" actually exists? What does it mean to "act like a dog"? And did it escape your notice that drastically different breeds have drastically different temperments and character? Maybe you're not much of a dog lover.It seems to me that you're setting up a fairly circular argument: "How do I know that they're still dogs? Because they act like dogs. Why do I conclude that, even though these examples all act differently, they all 'act like dogs'? Because they're all still dogs." Well, I don't know what to tell you. If your definition of "macroevolution" relies on models of biology that don't match reality, how are we going to meet it? Our responsibility is not to meet your own personal definition of macroevolution; it's to demonstrate that the predictions and explanations of the theory of evolution are accurate, true, and match the observed reality. And they do. The fact that evolution doesn't match the biological fantasy that exists in your mind is not evidence that the theory is wrong.

Two facts should change your mind:The average rate of mutation for mammalian nuclear DNA is roughly 3.1 mutations per billion base pairs (roughly about the same for other classes of organism); andAll functional protein sequences are separated by only one single amino acid change.In other words, there's no functional genetic sequence that you can't arrive at by just one change to another functional sequence; there's no path from one protein to another where you have to go through an intermediate, non-functional stage. The barrier to change you propose simply doesn't exist; it's a mathematical impossibility. Let me leave you with the words of Denton:

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One of the most surprising discoveries which has arisen from DNA sequencing has been the remarkable finding that the genomes of all organisms are clustered very close together in a tiny region of DNA sequence space forming a tree of related sequences that can all be interconverted via a series of tiny incremental natural steps.

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No, it's not. I mean, you're making this up. How can a variation represent a loss of diversity?If you meant that selection results in a loss of diversity, well, yes, we've all already agreed with that. But either you have no idea what you're talking about, or you're getting really sloppy with the terms. Possibly, you never understood the terms in the first place.Loss of diversity does not accompany phenotypic variation. Phenotypic variation, by definition, is a result of increasing genetic diversity, as well as a result of regular sexual reproduction (which is not the norm among organisms.) Well, you've just done that for me - you've asserted that the mechanisms you refer to can't result in increasing genetic variation. Mutations do, by definition. Thus, the effects of mutation can't be explained by the mechanisms you've just outlined.Like I said, you just proved it for me. I just did. If you don't understand that then you're not familiar enough with molecular biology to intelligently critique evolutionary theory. If you found my information obfuscatory, that's simply because you lack the familiarity with molecular biology required to intelligently assess arguments and evidence from it.

If a kind is everything that is decended from an original ancestor, then there's only one kind in that picture.

No, he agreed that selection represents a loss of diversity. You just said that variation represents a loss of diversity, and that's incoherent - diversity is the number of variants in a group, so more variations means more diversity.You're contradicting yourself, and it's probably because you're playing fast and loose with terms.

But that's not the trend. The trend is that mutation overcomes the elimination of diversity over time. This is borne out by observation, and in the fossil record.Diversity increases over time, due to mutation. Even though selection reduces diversity, it doesn't reduce as much diversity as mutation puts in. The faucet is bigger than the drain, so the tub fills.To say anything else, to say that the opposite occurs, is make-believe. It's fiction. It's you just making things up. What you say happens, doesn't.

Mick gets exactly what I get. If you think he's agreed with your entirely counterfactual statements about genetic diversity, then you've completely misunderstood his post.To say that variation means less diversity is to say that up is down, or black is white. It's nonsense. Why can't you see that?

That doesn't make any sense. Species are populations. A variation is an individual. Like I said, you're playing fast and loose with terms that aren't synonymous. No, it doesn't. If you have a population with three races, let's say; and later that population has four identifiable races, then diversity has increased. You can't have greater variation from less genetic diversity; it doesn't make any sense.What Mick is telling you is that the reproductive separation of a migrant group from a ancestor group connotes a loss of genetic diversity for the ancestor group. But that has nothing to do with phenotype or variation. It's about interrupting gene flow.You're conflating two entirely different concepts: phenotypic variation of individuals and reproductive separation of populations. They're not the same, and it's your sloppy thinking here that prevents you from understanding Mick's point and seeing the flaws in your own. It's not a sematic problem but a meaning problem - you're using terms without understanding what they mean.

Well, in this thread, I think she's arguing from the evolutionary premise. Seems to be, anyway.

Do you understand what the word "phenotype" means? Why don't you define it for me. What is a phenotype? Because you don't seem to be using it correctly if you think that an increasing number of phenotypic variations represents a loss of genetic diversity. We can't understand what you're saying because you appear to be using words you don't understand. It's gibberish.

So, you don't know.Let me tell you. Individuals possess both "genotype" and "phenotype"; genotype is their specific set of genetic characteristics, and phenotype is their specific set of physical characteristics. Whether they have green eyes or blue. Whether they're tall or short. Those things constitute an individual's phenotype.Phenotypes vary between individuals because individuals have varying genetics (genotypes.) Absolutely none of those processes will result in phenotypic variation. Rather, those processes contract and reduce phenotypic variation by contracting genetic diversity. Phenotype is the physical expression of genes. Any contraction in genetic diversity must result in a contraction of phenotypic diversity.Genetic diversity expands as a result of mutation. Also, sexual recombination is a source of additional phenotypic variation, but the effect is more relevant to selection than to mutation. We're having a problem because you're using the word "phenotype" without actually knowing what it means.

Well, I'll tell you what happened to Mendelian genetics - the model of dominance/recession is largely inapplicable to the majority of genetic interactions. A high school biology education will give you the impression that all or even most genes have only two alleles, where one is dominant and the other recessive, but they only do this because it's the simplest genetic model they can teach.The majority of genes are expressed either via incomplete dominance or codominance. The simple dominance that you're familiar with is more appropriate as a teaching tool, as a simple genetic model, than as a guide to the majority of genetic interactions.Of course, dominance itself only applies to diploid organisms. Asexual organisms have no dominance scheme because they have only one copy of each allele. The Mendelian model doesn't explain why a given gene has a dominant allele and a recessive one in the first place. You assert, I presume, that those alternate alleles were built in during the Creation week, or whatever; but the scientific observation is that mutation is responsible for these alternate alleles, and this explanation only contradicts Mendelian genetics in your mind. Certainly it doesn't in reality. Again you're using the word "phenotype" incorrectly. Phenotypic diversity is always indicative of genetic diversity. The word you're looking for is "species"; you're conflating isolated populations with individual morphological variation.

I don't understand where you think anyone here has proposed that. Let me see if I can lay it out for you how it works under a Mendelian model where mutation occurs.Sexual organisms still inherit half of their chromosomes from one parent and half from another. They still inherit two copies of each gene, one from each parent (with the exception of certain genes on the Y chromosome). Sexual reproduction still results in recombination of these different alleles, and some of them are expressed acccording to a scheme of simple dominance, some according to a scheme of imperfect dominance, and some according to a scheme of codominance. Sexual recombination alone accounts for a fair bit of individual physical (or phenotypic) variation.But...Individuals also inherit genetic sequences from their parents that their parents did not themselves inherit; these new sequences are unique additions to the population's gene pool. Mutation is the source of these new alleles. Allow me to reiterate that this is proven scientific fact.Mutations aren't "tossing anything together." They're a source of new alleles in the population, and a source of variation among individuals. They're the reason that you look like the people in your family, but you don't look like the people in mine. No, they don't. New phenotypes emerge as a result of new geneotypes, which themselves result from sexual recombination and random mutation. New species result from reproductive isolation, and that does generally result in a loss of genetic diversity in the ancestor population, when the speciation is allopatric. Mutation is the built-in genetic component. It's built into our genetics that mutations will occur.

How about you make a fucking effort? You're not going to be able to understand my posts if you don't understand my terms; and if you insist that "reproductive isolation leads to phenotypic diversity" then you don't understand the terms you're employing.We're not going to play a game where I speak one language, and you speak your own. That's not how this works. You need to make the effort to employ your terms correctly. Otherwise what you're saying is just gibberish. Nobody knows what the fuck you mean, because you insist on speaking gibberish. Use the terms correctly, or don't use them. You don't get to simply substitute your own ideosyncratic definitions and then complain when we refuse to play along.It's time for you to grow up about this. Start using the terms correctly, or don't use them at all. Oh? "Stupid" is exactly how I would describe someone who, after being shown error, refuses to correct their behavior. Grow up about it, already. No, you don't. And this gets back to how you refuse to abandon the decades-discredited concept of species essentiallism. Species are not characterized as species because of physical characters; it's reproductive isolation that defines species. You can have two seperate species that are physically identical, with the exception of a genetic incompatibility that prevents interfertile hybridization. Over time, they develop morphological distinction, because of the interruption of gene flow between them; but that distinction is not an immediate result of reproductive isolation. Absolutely impossible, according to the Hardy-Weinburg model. If you have a situation of simple dominance, and the presence of recessive genes, you'll always have individuals who are homozygous recessive.Always. The original population will always have included these individuals, for as long as the recessive gene has been present. And where did the gene come from, originally? Mutation. And neither do I. I've been telling you this, now, for most of this thread. Is it just that you aren't paying attention, or what?This message has been edited by crashfrog, 11-28-2005 02:52 PM