The End of Evolution By Means of Natural Selection

Hi Faith, Hold that thought and savor it. Dominance of a neutral allele is unrelated to it's selection (because it is neutral).Perhaps then we can relate this to your concept of hidden alleles that emerge in small populations ... presumably because other alleles that have kept it hidden are lost.Enjoy.

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I don't see how if black is dominant to all the others, brown is dominant to grey and grey is dominant to tan. If there is no reproductive advantage operating at all then they should sort themselves into a descending order of proportions from black to tan more or less as Zen Monkey laid it out.But of course, as you said.Edited by Faith, : No reason given.

I don't believe I've made that mistake. RAZD. I described such a situation a few posts above, which I just sharpened up by edit based on this discussion -- bottom of Message 366.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

The black allele might be very rare. If only 1% of the alleles in the gene pool are for black, then you get about 1.75% of the population with a black trait.

Well, yes, of course, and I've been working with that kind of example myself in my argument, but in this case I was trying to stick with a "perfectly" proportioned population because I thought that was what Zen Monkey was doing.

Hi, Wounded King. Well, she did acknowledge that at least one of the mutations I presented did have a beneficial effect on the bacterium's phenotype. Of course, she found another philosophical viewpoint to preserve her original argument (at least in semantic form), which is a product of a larger issue than her denial of beneficial mutations.I realize that I made no ground in convincing her of the importance and logical power of scientific theories. Like so many creationists, she has concluded that the "ideal" version of science is a simple fact-gathering enterprise with no thinking involved beyond the planning needed to design experiments for the collection of data.As long as she holds to this opinion and refuses to accept that theories are not endpoints--but also sources---of knowledge, getting her to acknowledge one or two of our factoids is a only pyrrhic victory.I think you're right: her issues are deeper than just this specific argument.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

That makes sense to me. The frequency of the Black allele in one generation, no matter how dominant, would stay the same in the next generation because there are only so many rabbits to go around. If only one rabbit has it, whether heterozygote or homozygote, then he or she is still only going to be able to pass it on once in any single given mating.Thanks.

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I have no time for lies and fantasy, and neither should you. Enjoy or die.
-John LydonWhat's the difference between a conspiracy theorist and a new puppy? The puppy eventually grows up and quits whining.
-Steven Dutch

That was my assumption, trying to be as simple as possible while still being reality-based.

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I have no time for lies and fantasy, and neither should you. Enjoy or die.
-John LydonWhat's the difference between a conspiracy theorist and a new puppy? The puppy eventually grows up and quits whining.
-Steven Dutch

Hi Faith Except that your supposed hidden alleles were never seen in previous populations, and this does not fit with the patterns above. In every 16 rabbits (if the alleles are evenly spread). If we assume that 50% of the Black alleles are knocked out of the population by some stochastic event, then there are twice as many of the other alleles than the black alleles (to keep the math relatively simple), and then we get:

	Black	Brown	Brown	Gray	Gray	Tan	Tan
Black	Black Black	Black Brown	Black Brown	Black Gray	Black Gray	Black Tan	Black Tan
Brown	Brown Black	Brown Brown	Brown Brown	Brown Gray	Brown Gray	Brown Tan	Brown Tan
Brown	Brown Black	Brown Brown	Brown Brown	Brown Gray	Brown Gray	Brown Tan	Brown Tan
Gray	Gray Black	Gray Brown	Gray Brown	Gray Gray	Gray Gray	Gray Tan	Gray Tan
Gray	Gray Black	Gray Brown	Gray Brown	Gray Gray	Gray Gray	Gray Tan	Gray Tan
Tan	Tan Black	Tan Brown	Tan Brown	Tan Gray	Tan Gray	Tan Tan	Tan Tan
Tan	Tan Black	Tan Brown	Tan Brown	Tan Gray	Tan Gray	Tan Tan	Tan Tan

So all the possible pairings give us 13 Black rabbits, 20 Brown rabbits, 12 Grey rabbits, and 4 Tan rabbits in every 49 rabbits (if the alleles are evenly spread). Not really a significant change in proportions for an impact of 50% of the Black alleles being removed. The population as a whole will still be predominantly Black, Brown and Gray in appearance, while the rare Tan rabbit goes from 6% to 8%.The allele that benefits (increases in appearance of the phenotype) the most from this change is the Brown one, the second most dominant allele in the original population, as essentially Black and Brown exchange places.Somehow I don't think this validates your claim.EnjoyEdited by RAZD, : added endEdited by RAZD, : added carriers

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No, of course you don't see that. This is because you have never studied genetics even so far as to understand even the words that you are using.I may have said this before. And I am going to say it again.You are hopelessly ignorant about genetics, so what you need to do now is to get a basic textbook about genetics so that you at least know the meaning of the vocabulary that you are using.For pity's sake, Faith.

Well, it's never my intention to talk complete rubbish, but it does happen from time to time.As PaulK points out above, I was, however much I tried not to, confusing the allele with the trait. I believe that given the somewhat artificial constraints of the problem - no mutation, a single trait being determined by a single gene, random mating, and a trait with no reproductive advantage or disadvantage - that this should end up being mostly about math. Thus I turn to you, Dr.The pairings that I did were inadequate, as I now see. If I start with a standard Mendelian square, this is more like it. I think.Here's what happens when I do the math by brute force. I'll start out as simply as I can: just two alleles with Black (B) dominant and Brown (r) recessive to respect to each other. If a homozygous (BB) black rabbit mates with a homozygous brown (rr) rabbit, then I believe we have 100% probability of black offspring, as all four possibile outcomes will be heterozygous Br, and thus an even distribution of alleles. Breed any two of those heterozygous Br rabbits, and we have a 75% possibility of a black pup and 25% possibility of a brown one: BB, Br, rB, rr. If I then look at all the possible combinations of any two of that generation of rabbits mating at random, we'll have 16 potential pairings, which can happen in six different ways. (For the sake of my own sanity, I'm going to represent both Br and rB as Br.)1. BB + BB = BB, BB, BB, BB
2. BB + Br = BB, BB, Br, Br
3. Br + Br = BB, Br, Br, and rr
4. BB + rr = Br, Br, Br, Br
5. Br + rr = Br,, Br, rr, rr
6. rr + rr = rr, rr, rr, rrOut of the 16 possible pairings, I see that combination 1 can happen only once, combination 2 can happen four times, combination 3 can happen four times, combination 4 can happen two times, combination 5 can happen four times, and combination 6 can happen only once. So out of the sixteen possible pairings, we'll have 64 possible outcomes:BB x 16 (25%), Br x 32 (50%), and rr x 16 (25%)So it looks like once again we'll have 75% probibility of black offspring and 25% probibility of brown offspring.I hope that I'm still doing ok.So the question comes down to this. Given a situation in which we don't allow our rabbits to breed exponentially, however much they might want to, but stay at a simple replacement rate of one pair producing two offspring per generation, will this ratio of distribution of alleles and traits remain constant from generation to generation? (I assume that a steady replacement rate would represent a static environment and a stable population.) I get completely lost in trying to work with more than two alleles - dealing with two for just three generations was hard enough. But can I assume that the same concept of a consistant probability for the distribution of alleles across the generations would hold?I brought this question over here since it's actually somewhat peripheral to my train of thought over on the Great Debate thread, but I wanted to clear it up for myself. Obviously I did indeed need quite a bit of clearing up.Also, I think that my second question is the more interesting one. Is it possible, in the above scenario, for a recessive allele to remain unexpressed as a trait entirely, or is the probability for that too slim?

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I have no time for lies and fantasy, and neither should you. Enjoy or die.
-John LydonWhat's the difference between a conspiracy theorist and a new puppy? The puppy eventually grows up and quits whining.
-Steven Dutch

The ratio will drift a little due to randomness. If there is a selective advantage for some combinations, then it will change more than just random drift. Yes, still the same with multiple generations. The ratio remains nearly constant, except for a little drift due to randomness. If the population size is very small, that could happen. With any significant population size, the probability is so low that you would not expect it. If it was observed that the recessive trait never appeared, that would probably be taken as evidence that it is fatal.

RAZD, you seem to be making up my side of the argument for me.I've given many different examples over the thread. The example I was giving above, using Zen Monkey's hierarchy of fur colors, was of a population in which black had come to so completely dominate through drift or some kind of selection process that the expression of a homozygous recessive just about never happened because it would be that rare in a very large population of predominantly BBs for the pairings to occur -- and the BBs are so prevalent BECAUSE black has been severely selected. The others might of course still occur. But the point is that in a migration to start a smaller daughter population it could happen that you'd get enough of the heterozygous blacks to increase their frequencies relative to the BBs and that would allow the other colors to be expressed far more than in the parent population. It's a really simple example, simply another example how it IS the change in gene frequencies alone that changes the phenotype for the new population without any addition of mutations.Whatever happened to the definition of evolution as change in gene frequencies anyway? This supposedly describes what happens through selection or drift or migration -- you shouldn't need mutations to get a new character to a new population.{ABE: My argument, just for a reminder, is that it is the SELECTION processes -- including drift and migration and so on -- that change the frequencies, and dominant and recessive alleles come into play as a way of explaining how under selection some traits could completely disappear from a population or at least become extremely rare and then start showing up in greater numbers in a daughter population. Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

Only if the population is infinitely large.If it isn't, and if no new mutations occur, then given enough time one of the variant alleles must become fixed in the population. And the question of which allele is "dominant" has nothing to do with which one will become fixed.If new mutations do arise, which they will, then the question becomes moot.

What "happened" to it? It's still there (pace your slight misstatement) and one day we hope that you'll understand it.Again I would urge you to get your hands on some basic text about genetics and read it.