Random mutations shot down on this site.

If you look at if from a population dynamic point of view, "micro"evolution would involve all the mechanisms for genetic mixing and selection within a breeding population, and "macro"evolution would involve the mechanisms for change and selection between non-breeding populations.The former tends to keep populations fluctuating about a mean within any ecosystem (stasis), the later tends to force newly diverging populations apart via competition for the same resources and eco-niche - change or perish. Once two diverging populations have diversified sufficiently so that they don't compete directly for the same resources or eco-niche, then they can settle down to a more peaceful co-existence.Thus "micro" is change that occurs within breeding populations and "macro" is change that accumulates between non-breeding populations. Anything beyond that is subjective to classifications (which are arbitraty human inventions).Enjoy.

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The wiki article doesn't say that each tree has to have an equal chance at mating with any other tree.Random mating just means that it happens randomly rather than by any kind of design (selection). The wind blow, and pollen is released. The wind happens to blow the pollen onto the flowers that are downwind.

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But, doesn't that fall under this category:

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In other words, the mating between two organisms is not influenced by any environmental [...] interaction

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Edited by Doddy, : Fixed BBCode

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"Der Mensch kann was er will; er kann aber nicht wollen was er will." (Man can do what he wills but he cannot will what he wills.) - Arthur Schopenhauer

Yes, the obvious. Random mating does not mean equal opportunity to mate with all organisms in the population regardless of geographical distribution. Definitions of random mating do not usually mention the incredibly obvious effects of geographical distribution because they are so, uh, incredibly obvious.There's a question I've put to you several times, and I think that if you try to answer it that it will help you see where you're misunderstanding things. Name a species for which the opportunity for an individual to mate with all other individuals of the same species is equal. You won't be able to do it. No such species exists. Now ask yourself why random mating is described as if it were something that is actually observed? The answer is that it is observed. Random mating exists and has been observed. So since by your understanding of the definition of random mating it isn't possible and so shouldn't be observed, your understanding must be incorrect.Leaving out pieces of the definitions you gave doesn't help your cause. For example, this is the full text of your last definition: "In the ideal case, each individual in the population has the same probability of mating with every other individual. In practice, no selection influences the matings that occur."The Wikipedia definition is better (Panmixia - Wikipedia), as is the definition at this very site (http:///WebPages/Glossary.html#R).--Percy

Obviously Wounded King already has a copy of the article, for he provides far more information from it than appears in the abstract. Could you please provide excerpts of the sections of the article that you think support your position?--Percy

Sorry, I'm fairly sure that it does. All genetics simulations that I've encountered do this when set to random mating. As one of the assumptions of the HWP, random mating is described. Infinite population size can't be observed in any species either, but that doesn't mean it is a useless definition. I only left that out because I was referring to the ideal case, as is used in computer simulations of HWE, and not the approximate practical case. Just like in practice a population just has to be big for the HWP's assumption of infinite size to be a good approximation, it just has to be somewhat random (not too skewed) for it to work there too.But, it appears we are both using different definitions - I refer to the theoretical, and you to the real-world.Edited by Doddy, : Fixed a bit of spelling

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"Der Mensch kann was er will; er kann aber nicht wollen was er will." (Man can do what he wills but he cannot will what he wills.) - Arthur Schopenhauer

Other days the wind blows other directions. You can develop a topographic map of probability of pollen falling from a given source.Where the pollen actually falls is still a random distribution within that map.An environmental influence would be one that operates constantly to affect mating in one direction (adapting to the influence).All you need to do is watch a long-leaf pine in the south on a windy day and see the clouds of yellow pollen drifting away from the trees -- where it ends up is not directed, it's random. Longleaf Pine article

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Abstract:
A high ratio of pollen drift to deposition and the high level of pollen found in an open area suggest that Pinus palustris forests fill the air with pollen that travels for long distances, with density declining mostly through diffusion rather than fallout.

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My red truck turned orange when the pollen was flying in Pascagoula MS. And woe to anyone with allergies.Enjoy.

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I think you are wrong. I bothered to go get the whole article through my public library. Try it. You would be impressed with their drift v. selection model.

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I bothered to get the article as well (I can get it online, so I didn't exactly have to go out of my way). The article does NOT detail what forces cause speciation. The first sentence of the introduction says:

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Mutations can spread through a population either by random genetic drift or by the action of natural selection. The relative contributions of these two processes to evolution at the DNA level is one of the oldest and most keenly debated questions in molecular evolution1,2.

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and that is, in essence, what the paper is about. It compares the proportion of substituting mutations that are thought to be due to drift versus those thought to be due to selection. I think you might be arguing that just because two species are compared then it somehow follows that any differences found was the cause of speciation. This is not true, and the authors certainly never argue it. The closest they come to saying anything about speciation is when stating:

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We assume that advantageous mutations contribute little to polymorphism, although they may contribute substantially to the divergence between species.

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Divergence between species does not necessarily lead to speciation (although it most likely is a requirement) and moreover they are not talking about drift.

Surely until they actually have undergone speciation what you have is simply divergence between two sub-populations of one species, it is illogical to talk about a divergence between species being required to lead to speciation, though clearly genetic divergence between sub-populations or sub-species is required.TTFN,WK

On this site what you think doesn't hold much sway, what you can back up is considerably stronger. Yeah I did that a lot at university, I'd go and spend an afternoon looking up references and photocopying articles, it sure beat reading them. Or did you mean that you got the article and read it? I did, how else did you think I was quoting from the body of the text? Not hugely no, it takes a little bit of massaging of the data before they actually get a significant result. Its probably a good enough model for what they are doing, but I was much more impressed when I first came across Kimura's neutral theory which this is really just supporting evidence for.If you look at the beginning of their explanation of the model you will see. So one of the key elements in the model is the time since the species diverged. Now I will grant that if these were two geographically isolated populations then there is scope for plenty of genetic divergence prior to the establishment of reproductive isolation between the two species, what we might call the definitive point of speciation, but this paper doesn't look for this point at all. This paper simply looks for the genetic differences that have accumulated in the time since the two populations stopped sharing a gene pool.It doesn't ascribe any proportions of drift or adaptive selection to the actual speciation event. If you think it does then show where it does, don't just go 'nuh-uh'. You moan that we are trying to hold you up to the standards of scholarship and peer review but you seem to want to drag the level of debate down to that of the playground.TTFN,WKEdited by Wounded King, : No reason given.Edited by Wounded King, : Because I don't know how to type.

Okay. For the purposes of this discussion then, although I hold that the terms "micro-" and "macroevolution" are meaningless outside the narrow original usage defined by paleontologists, you are defining "microevolution" as "adaptation", and "macroevolution" as "evolution between taxa". Is this correct? If so, to move the conversation forward, at what level does speciation occur by your definition - micro or macro?Before you respond, you should probably consider some of the implications of the above. For instance, the way you have defined adaptation, "microevolution" cannot occur through drift, as drift is non-adaptive. In fact, you can't have microevolution/adaptation without selection under your schema.Secondly, I think you're going to find it difficult to justify microevolution=adaptation in the first place. WK gave you a hint when he mentioned in passing Kimura's neutral selection theory. In other words, if Kimura was right (and there seems to be mounting evidence that he was - including the very paper you referenced), you can have "evolution" (writ small as "change in allele frequencies in a population over time") - or as you define it: microevolution - without adaptation. The effect of drift is one example. In fact, as I pointed out earlier, drift in the absence of countervailing selection can actually have the opposite effect to adaptation - rendering a population less fit. I don't think you can call microevolution "adaptation" and leave it go at that. I don't want to get too far off topic with a discussion of the Cambrian so-called "explosion", so I'll be brief. In the first place, with the exception of the proliferation of life-forms who "learned" (apologies in advance for any deliberate or inadvertent anthropomorphisms) to incorporate calcium carbonate or other minerals into their bodies, the radiation in the Cambrian wasn't really any more impressive than the radiation of mammaliforms following the Cretaceous extinction event. Sure, there was a whole bunch of different adaptations occurring during the Lower Cambrian leading to different body plans (that today taxonomists call "phyla"), but to be honest there were sufficient precursors in the Pre-Cambrian (especially the really interesting Vendian assemblies) that whereas we might not have specific "ancestral" organisms for each new body plan, there are enough possibilities for enough of the "new" phyla to infer that it was adaptive radiation rather than something wholly unknown that led to the Cambrian diversity.To try and put the Cambrian radiation into perspective: looking at the modern diversity of species which we place into a hierarchical taxonomic classification culminating in the phyla whose first examples occur in the Cambrian, we are talking in some cases of literally hundreds of thousands if not millions of species. In the Cambrian, however, these crowded phyla were represented by one or at most a handful of species. Given what we know about how speciation occurs today, it doesn't take a genius to see that the limited biodiversity - hyperbole aside - of the Cambrian is relatively easily explained by radiation from a few ancestral types. In short, there was no "evolution between taxa". After all, some organism had to be the first...

I think you're right. No one expects Hardy-Weinberg to apply to the real world. It's a nice approximation and useful for the study of population genetics - especially for modeling theoretical frequency shifts, but it really isn't all that close to what happens "in the wild". One of its key assumptions, in fact, is that sexual selection doesn't exist (or rather can be ignored). I don't believe there IS a sexually reproducing non-plant species where this doesn't happen to one extent or another. The plant kingdom gets a little odd, of course. Sexual selection really DOESN'T apply to plants. And plants - at least the ones that don't forego the whole problem by self-fertilizing - are about as close to "random mating" that you can get. However, the wiki article you cited eliminates plants (real ones, anyway) from consideration as well - there are a number of biotic and abiotic factors that constrain "random" fertilization in almost every plant that doesn't self. And even there...

Any simulation that does this is only making an approximation of the real world. And it can be especially helpful to ignore considerations of geographical distribution when that is not a factor under study. Ah, okay, I see what has happened. You're interpreting what I'm saying in terms of idealized models, while I'm talking about the real world. But it was clear from the beginning that I was talking about the real world, because so were you. You were talking about trees in a forest in your Message 35. I quoted what you said about trees just above my response in my Message 40, and here it is again: I don't know where you got the idea that my comments had somehow shifted focus from your concrete example of trees in a forest to the other discussion concerning idealized models, but no such shift ever occurred.--Percy

Yes, I will. Firstly, let me say that my interest here is to find ways to differentiate natural selection from random genetic drift. I originally brought this us to explain to DigDug Master that mutations fixed by natural selection is not the only way that evolution happens. From there we may have strayed off topic, which is my fault.However, responding to your request, I'll say this: Smith and Erye-Walker attempted to differentiate amino-acid substitutions attributable to “positive selection” in Drosophila species from those substitutions that may be attributable (at least partly) to drift, which is NOT considered to be "selective." In this regard they wrote:

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Mutations can spread through a population either by random genetic drift or by the action of natural selection. The relative contributions of these two processes to evolution at the DNA level is one of the oldest and most keenly debated questions in molecular evolution. Yet despite extensive analysis, no consensus has been reached. With the great increase in single nucleotide polymorphism data, however, we are now in a position to tackle this question.

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They use good methods, IMO, to estimate that 45% of all amino-acid substitutions have been fixed by natural selection, leaving 55% attributable to non-selective substitions, such as by random genetic drift.

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We have estimated that approximately 45% of all amino-acid substitutions between D. simulans and D. yakuba have been adaptive. There are about 13,600 genes in the Drosophila genome, of average length of 590 codons, and the average number of amino-acid substitutions separating D. simulans and D. yakuba is 0.074 per codon (calculated from our data); we therefore estimate that there have been approximately 270,000 positively selected amino-acids substitutions in the evolution of D. simulans and D. yaluba. Given that D. simulans and D, melanogaster are thought, on the bais of biogeographical data, to have diverged 2.5 Myr ago, we estimate from the data in Table 2 that D. simulans and D, yakuba diverged ~6Myr ago. This implies that these two species have undergone one adaptive change every 45 years, or one substitution every 450 generations if Drosopjila undersgoes the generation a year. This is consistent with Haldane’s cost of natural selection, the problem which motivated Kimura to propose the neutral theory of molecular evolution.

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To me, this is a credible attempt to differentiate, as casual factors attending microevolution, the actions of natural selection from those of drift. Others may disagree for their own reasons, but I don't think anybody knows for sure or for certain how to measure or model a clear distinction between evolutionary causes. Smith and Erye-Walker make a fair shot at it, I think.”Hoot Mon

I don't know about 'darging down the standards of scholarship.' You're just angle-biting, like crashfrog. Please tell me what is wrong with what I said to Percy in Message 59. And, btw, why haven't YOU posted some relevant literature to defend your position on drift v. selection?”Hoot Mon