Unclear. Alleles don't contribute something to a gene so that it is functional; the alleles ARE the gene. I assume you realize this, but the way you word these statements at times makes it seems like you think alleles and genes are different things. Alleles are different FORMS of a gene. If a gene is functional then there must be at lest one allele; if there is at least one allele, the gene is functional. Losing alleles in and of itself does not affect gene function.
Yes I do know that, but in practice I think I tend to identify the gene itself with its location and its forms as something separate because they are interchangeable. If it's confusing I should word it more clearly.
The bottlenecked population's genes aren't changed, it's only as they inbreed for a few generations that the loss of alleles becomes apparent and we find many fixed loci developing for lack of alternative alleles.
Just a clarification. Inbreeding itself does NOT change the proportion of alleles (ie. it does not eliminate alleles), it only shuffles them into homozygotes. An extreme inbreeding event (such as selfing which humans are not very good at) would result in 1/2 the population homozygous for allele A and 1/2 homozygous for allele B. Unless there is now some barrier generated, these populations will eventually begin to outcross and will restore the heterozygous proportion rather quickly. A change in allele frequency requires drift or selection, both of which can result from inbreeding, but are not necessarily a consequence. So, diversity is reduced by the bottleneck but would then remain stable unless acted on by drift or selection.
Inbreeding doesn't change the proportion of alleles, but it can mix a new set of gene frequencies in ways that appreciably change a subpopulation. I think inbreeding of a new set of gene frequencies in a new subpopulation alone can make a change in the genetic substrate over time, though I can't say I know how it works well enough to lay it out. The new gene frequencies alone constitute a "selection" event that over time changes the character of the new population, or both populations that formed from the original population, if both have significantly changed gene frequencies. If some traits are governed by more than one gene and all the frequencies are different then the new combinations occurring in reproductive isolation could be pretty complicated, and traits that never appeared in the original population could now start showing up, even possibly in the first reproductive season. Mostly due to dominant-recessive changes I'd suppose. There may be other selecting factors too such as drift, in fact there probably are, until after how ever many generations it takes for all possible new recombinations to occur (it probably doesn't have to be "all possible" of course) the subpopulation(s) should look appreciably different from one another. And if reproductive isolation continues through more generations the rarest alleles (which could be different alleles from those earlier) should stop being passed on altogether and eventually just from the inbreeding of this new mix there could be enough of a genetic mismatch to prevent interbreeding with the original population and other subpopulations. COULD be. Without any further genetic input such as mutations or anything else. So when two highly inbred isolated populations do happen to meet, you'll have well developed traits from the same set of genes that are different enough, based on different enough allelic mixes for those same genes either to make interbreeding impossible or to come up with such an entirely new combination the hybrid will be dramatically different itself. This is what I'm thinking, but again spelling out how all the different combinations could occur is beyond me. The point, however, is that I think you don't appreciate the many new effects possible from simple new frequencies of genes that inbreed in reproductive isolation over many generations. All because the frequencies are different between the daughter and parent populations -- more of some alleles, fewer of others, so inbreeding alone will change the recombinations you get.
In the case of cheetahs and elephant seals it is mostly selection that is causing a lack of recovery.
How would that work? Both populations have such a high number of fixed (homozygous) loci brought about by the "selection" event of the bottleneck that brought about their current genetic condition there are no alternate alleles to be selected for those particular traits.
In the case of humans after the flood, it doesn't seem to me that the population had any difficulty recovering.
Well neither did the cheetahs or elephant seals, despite their genetic depletion. The population of seals recovered enormously and the cheetahs seem to be doing OK too. All the original ark species should not have been genetic depleted anyway, that being something that only happens now after millennia of population splits, and humans still have a great deal of genetic diversity anyway.
Do you have an argument as to why selection was acting on the post-flood population and it was unable to recover rapidly?
I don't know what you mean by "selection" in this context. And all the species recovered just fine, except maybe the dinosaur clans, and went on to propagate a huge variety of subspecies just from whatever genetic diversity they possessed even in their small numbers at the time of the Flood.
Then in the formation ... small subpopulations in the wild which we've been discussing, the reduced genetic diversity should also trend to an increase in fixed loci due to its loss of alleles that remain in the larger general population.
This is a statement that you should be able to back up with evidence. Show us some subpopulations where it has been demonstrated that the subpopulation has increased in the number of fixed alleles.
This would be the case with any "purebred" domestic breed, which is said to be characteristic of pure breeds. Otherwise you'd find it in conservationist's concerns about genetically depleted species in the wild. I have suggested that you could sequence the DNA of the series of populations in ring series, avoiding hybrid zones, to find this out. And this is also what my laboratory experiment would be designed to demonstrate, by artificially creating random reproductively isolated subpopulations and allowing them to inbreed for some number of generations and then creating new random subpopulations from those groups and so on, noting changes in traits and doing DNA readings from population to population and even generation to generation, the expectation being that you should be getting identifiably reduced genetic diversity from subpopulation to subpopulation, with fixed loci increasing and eventually dominating. I don't know of any evidence of this at this point, though you seem to think it should be available.
In the case of domestic breeding the more fixed loci the more "pure" the breed.
A more accurate way of saying this is that to ensure that a trait always breeds true then the trait needs to be homozygous in both breeding individuals. You want the traits you are selecting for to be homozygous, but traits not being selected for you want to have variability.
The descriptions I've read sound more like what I said, although it's basically the same thing you're saying. But also, just as a side note, while controlling for homozygosity of the characteristic (selected) traits you usually can't guarantee that others will remain variable.
Many genes would eventually be reduced to fixed loci and come to characterize the subpopulations that migrated to different parts of the planet.
Another statement you should be able to provide some evidence for. What "fixed loci" characterizes human populations today? There has been quite a bit of work done looking at the diversity of human populations and "races."
I'm not thinking of human populations because we retain so much genetic diversity, but if you want to look for fixed loci I'd say you need to look at subraces of subraces, such perhaps as the Pygmies who are known to have descended from the larger African population but aren't as dark and of course are smaller. Perhaps Mongolians and Inuit would show fixed loci at some genes too, having migrated from the larger Asian population and inbred over generations. Wherever you find smaller tribal groups I guess would be the place to look. Icelanders were an isolated inbreeding group that migrated from Ireland. Or how about the Amish?
I did have in mind that simply the existence of many fixed loci could result eventually in the loss of function of many of those genes, but right now I'm thinking there is no real reason why that would be so: destructive mutations would have to occur for that to happen, and destructive mutations should have been on the rise after the Flood too.
Also, if you have a population of say 1000 individuals, all homozygous at a particular loci, how many destructive mutations (mutations that deactivate a gene) would there need to be for that deactivated gene to propagate throughout the population - that is, until the entire population lost function of that gene? Or another way to phase the question, what would have to happen for that deactivated gene to become fixed in the population?
I suppose it depends on the size of the breeding population plus possible selection factors.
It is enormous, for sure, but it does seem to be what happened. To my mind it speaks to the far more enormous original genetic diversity all species had. The loss is incalculable, but here we are.
Yes, here we are... Faith's assertion of what happened without evidence. You have described your observations but have not provided empirical support that your conclusions about those observations are valid.
I don't think there IS evidence for most of these guesses, it would take a project to gather it, or set up my laboratory experiment. But your questions are good for helping clarify what I have in mind.
If some junk DNA isn't just disabled genes it would be much less of an effect but the vast majority do seem to be formerly functioning genes.
Case in point! What percentage of the human genome is "disabled genes?" How would you detect a "disabled gene," what would it look like. What are some examples of "disabled genes" from the literature. What is your estimate of the number of "disabled genes" and how do you arrive at that estimate?
I'd direct you to those who call disabled genes junk DNA, which is how I'm using the terms.
Unless you provide answers to questions like these, all you have is an observation from which you have drawn an unsupported conclusion.
It's either an interesting direction for creationists to take in looking for evidence, or it needs refinement or it's not a good direction. I think Darwin was wrong about natural selection being a significant cause of microevolutionary changes, but evolutionists aren't looking for evidence that Darwin was wrong, or anything that would question the basic tenets of evolution, they mostly take them for granted and add further assumptions according to their support of the theory. He didn't have genetic evidence available anyway, he just figured the changes in the finches' beaks were a response to the environment and that became the engine that drives the ToE; but what if the changes came about randomly through changes in gene frequency due to migration of a subpopulation of finches? I can propose the idea but I don't have any more evidence than Darwin had and it's not something mainstream science has any motivation to test.
Edited by Faith, : No reason given.
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