The End of Evolution By Means of Natural Selection

Hello bluejay, thanks for the nice welcome. I have been giving oversimplified examples trying to make my point but then you all come back with the subtleties and exceptions and so on. I'm trying to talk about a trend that I think is observable if one focuses on it. When you say NS just has to smite SOME of the competition, fine, I don't want to argue about HOW MUCH of the competition has to be smitten, I just want to focus on the fact that SOME get smitten! That NS smites! It smites the competition. That's its JOB as it were. It gets drastic only at the extremes, fine, like when a snake eats up all the nonpoisonous newts in a population and the poisonous ones then multiply. They probably still have the alleles for the nonpoisonous type among them too as this isn't yet speciation, but those alleles have been "smitten" in the sense that they can't express their phenotype, right? How, I don't know, something to do with dominance and recessiveness? If the poisonous newt continues to be selected eventually it could become a species and then the alleles for the other type will finally have disappeared, no?All I meant by getting a trait "established" was that ... OK I'm thinking of a ring species. The salamanders in California that ring a desert area. Each population has a different "look" to it than each other population, its own peculiar look that identifies it. Maybe I don't have this quite right but I assume that to get this look peculiar to its population required the blending of its own collection of alleles for various traits which occur in different frequencies among them than in the original population. The original founders of the new population would have looked like the population from which they came, but due to their smaller numbers, their different proportions of alleles, perhaps even the absence of some alleles altogether, they mixed together through generations in the new setting to produce this new phenotype, this new look, this new color pattern that distinguishes them from the first population. This is what I think of as "established" -- when the whole population has this new characteristic. They had to have time for their genetics to blend together into a new phenotype characteristic of their new population. Is this what "fixed" means?They don't HAVE to completely lose alleles for this to happen, merely have them in new frequencies, but the TREND down the series of populations IS toward the loss of alleles simply because each new population starts from a small number relative to its parent population.Edited by Faith, : No reason given.Edited by Faith, : grammarEdited by Faith, : bolding

PaulK:
I don't know if increased variation in mitochondrial DNA and hypervariable minisatellite loci contribute to the genetic diversity needed by the cheetah to recover or not. It isn't the normal expected source of genetic diversity so you'd have to tell me what it means.

Phage, I still struggle to get what you are talking about, and on top of that it looks like I didn't express myself very clearly either. If I can I'll come back to your post later.

I'm trying to demonstrate what the selective/isolating processes that lead to speciation do -- they reduce genetic diversity which allows a new phenotype to become characteristic of a new subpopulation. Plenty of other things are also going on that may change that direction but the isolating-selecting processes always work in the direction of reducing genetic diversity. If all kinds of mutations and new traits are accumulating you aren't going to get to an actual new species while that is going on.

The kinds do branch, they evolve. Some creationists do have a wrong idea of fixed kinds but that's really a very old idea and it's very clear that they evolve into many different varieties. This should have been known to creationists all along too because domestic breeding is an ancient art.

This isn't GENETIC diversity you're talking about. You're talking about the proliferation of varieties or breeds. Lots and lots of those, yes. But EACH of the breeds has been able to form BECAUSE it has its own reduced complement of alleles compared to the parent population. Edited by Faith, : typo

This is a complete misreading of what I'm doing and I'm at a loss how to correct it since it keeps cropping up. I am NOT "assuming" this at all, and my argument is not "based on" it. It is an OBSERVATION that the selecting-isolating factors determine the phenotype of a new subpopulation by reducing its genetic diversity. The variation that everybody is talking about comes in at a different point in the life of the species. Oh I can't get this said in any way that you aren't going to continue to object to in the same old way so I have to find new waysto say it. The variation you keep wanting me to take into account simply does not enter into what I'm trying to get said. So go ahead and assert that I'm ignoring addition and I'll just grind my teeth again.Edited by Faith, : correct run on sentence

I don't really think in terms of recovery, because bottleneck is just one way I see new species forming. I realize that at the level of genetic depletion we see in some species today, in this fallen world it's a hazardous condition to be in but I don't even think about the cheetah as some sort of deficient animal. I think of it as an elegant creature unfortunately born into a fallen world. The overhunted seals are thriving in great numbers despite their genetic depletion. Genetic depletion is a problem in this fallen world as it would not have been in the original created world, but even here animals in that state can sometimes do just fine. The process of genetic reduction is a way for wonderful new varieties to emerge, it's a very creative process, it is only unfortuantely deleterious in this death-ridden world.I assume enormous genetic diversity in the passengers on the ark, that has since played out in the many splittings and variations and speciations we see today. There would be no end to them if death had never entered the world.=========================================
I hope I will be forgiven for bringing any of my Bible-based beliefs onto a science thread, but clearly I'm simply responding to others who have brought up the subject and it may clarify some issues people have with my argument here. If anyone wants to pursue the topics raised it should be on another thread.Edited by Faith, : to add last paragraphEdited by Faith, : No reason given.

So natural selection doesn't enter into it with the finches? Or they aren't true species and could revert at any time?

Dear dear Dr. A. Yes I got annoyed at some way you expressed something and I apologize. I am now finally getting to your posts and it seems to me you are missing my point. My focus iIS on the individual evolving population, not the whole gene pool. I'm interested in how a subpopulation gets characterized by one single beak type -- because this is evolution is it not? -- and on the model of domestic selection I figured it could only occur if other beak types were eliminated from the population's own gene pool. Now Percy tells me beaks don't get selected like that but I'm sure there are plenty of other examples where what I'm describing is closer to what happens. I have no idea what you are talking about. I suppose I'm simply not doing a good enough job of making myself clear but believe me what I've been saying from the beginning is what I'm still trying to say. I'm also trying to learn from people's objections which I hope might improve my terminology and refine my argument but otherwise, no, same argument.

If you want to talk about what I believe about the ark please start another thread. I promised Percy I would not talk about Biblical subjects on a science thread.

Yes, I do keep forgetting the example of a selected allele working its way through a population generation by generation, and in that case you get the new trait without the loss of genetic diversity. Usually I'm thinking of the cases where a subpopulation of reduced numbers is created, which does eliminate alleles, does create a new population with its own identifying characteristics, and can lead to speciation. I'm thinking of the situation of reproductive isolation of a smaller number from a larger population, which is a main way new varieties develop, and even speciation. The process by which an allele becomes fixated seems to demonstrate the case I have in mind; it doesn't matter if it doesn't always happen that way, when it does it demonstrates what I'm trying to talk about -- if an allele DOES become fixated it happens according to the processes I'm describing does it not?Ring species keep coming to mind because they continue to form whole populations with strikingly unique characteristics by migration of small numbers from larger populations, a trend that has to involve progressively reducing genetic diversity from population to population as the new unique populations develop. OK, if you say so. I'm trying to talk about a trait that comes to represent an entire population, not just a trait that gets itself established as a variation within a population. I'm trying to talk about the evolution of whole populations, down to speciation. A bottleneck IS extreme genetic reduction. Which brought out a really great animal.

I'm not a uniformitarian. I believe things were very different 4500 years ago genetically speaking. And even MORE different before the Flood. When I'm talking about today's situation I don't bring that up. He brought it up. It's based on the Bible. It doesn't belong here.Edited by Faith, : No reason given.

I don't KNOW what people wrote two days ago. I don't have your perspicacity in knowing what's relevant and what isn't. And you can spare the insults if you want this thread to continue at all. Of course maybe you don't.

Can we please agree on a few things. Or not. Simple stuff.1) In domestic breeding -- let's stick to dogs -- do you agree that you get and maintain a breed by being sure you breed it with its own type?2) Do you agree that this is to protect the breed's particular allele complement from contamination from alleles of other dog types?3) Do you agree that any dog breed possesses a very limited genetic diversity with respect to the total dog population?4) Do you agree that it is its limited genetic diversity that is the basis for the characteristics of the breed itself and that if there is any increase in the genetic diversity the breed will lose its character at least to some extent?5) Do you agree that Darwin based his natural selection on domestic selection?6) Do you agree that natural selection is the "engine of evolution?"7) Do you agree that the end goal of evolution is speciation or is evolution simply any change at all whether it ever leads to speciation or not?Edited by Faith, : added two questionsEdited by Faith, : to add numbers for future reference if needed