Evolution Requires Reduction in Genetic Diversity

Thank you. I was trying to figure out what you meant by, "You haven't described anything about evolution. You've argued that mutations increase genetic diversity. That's not evolution." I made a guess and asked if it was correct. You said no but nothing more, so I still have no idea what you were trying to say.

Uh, okay. So let me replace the word "evolution" with "microevolution" in one of your sentences: But alleles being passed on randomly within a population is most definitely part of microevolution, so I don't think you mean "microevolution" either. Thank you. That would be very welcome.

I'm not trying to debate you. I was only requesting clarification about what you meant by this from your Message 735: You declined to provide any clarification, so I made a ruling. But now you've provided some clarification, so let me try to rewrite your passage in light of the clarification: Do I have this correct now?

which is:

quote:

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Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of a species.

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It would be quite a feat to count the TOTAL number of genetic characteristics in an individual let alone an entire species. I also disagree that genetic diversity should refer to total characteristics of a species, it should be of a population. Not really. Genetic diversity is more of an abstract concept. We don't report that "genetic diversity of population A is "X value." It's not hard to define the concept of genetic diversity, but to actually report the "genetic diversity" of a species is not realistic. Well, you are wrong. Heterozygosity is a measure we use to estimate diversity, to have an idea how much variability there is within a population, but it is not synonymous with genetic diversity. Neither is alleles per locus. Think about it, we could have a population with 2 alleles at a given locus with each allele at a frequency of 0.50 which would mean the heterozygosity is 50%. Then we could have another population with 3 alleles that is highly inbreed where heterozygosity is <10%. Which one has higher genetic diversity? What is the value of genetic diversity (and units) for each population? What numerical value for genetic diversity would be considered low or high? Genetic variability is the tendency of the individuals in a population to vary or to be different from one another. The measure of variability is how much difference there is between individuals within a population. A highly homogeneous population will have little difference between individuals while a highly variable population will have a large number of differences between individuals.Whenever we are making comparisons of populations what we are actually analyzing is the amount of variability. Variability is ubiquitous in natural populations - it is how much variation that we are concerned with, thus the types of questions we usually ask are "How different are these two populations?" (genetically or phenotypically)Genetic diversity depends on genetic variability. Populations with high variability will have high diversity. Populations with low variability will have low diversity. Variability is what we measure (heterozygosity is a measure of variability) to make inferences about diversity; diversity is not measured directly - it is too abstract, too large of an umbrella term. Think about it, if we measure the heterozygosity and the number of alleles for 10 loci of 100 individuals randomly selected from a population of 10,000, what would that tell us about the overall TOTAL diversity in the entire population? What about diversity at the other 19,990 loci? Do we need to include them in the study as well? I only proposed that in order to discuss the chart and the processes involved we use the easier to understand term of genetic variation or genetic differences. It IS relevant because that is what happens, populations in isolation tend to become genetically different from each other. It is these differences in genetic makeup that drives phenotypic divergence. See, I don't want to just say this is wrong. I want to explain WHY it is wrong and WHY it doesn't work and that it simply doesn't match what we observe in nature. But it is not just a simple matter to explain, it takes working through a process. I even proposed that in working through that process you could better understand your own argument and possibly make some adjustments so it might be more convincing. It is doing no good to just keep restating your position. We get it and it's wrong. You keep thinking that if we understood your argument we would see that it is right, but it's not that we don't understand your argument as you keep claiming, it's that your argument doesn't match what we observe in nature. (Or at least that is our counter-argument). I could just point you to some studies that show you what we actually observe and that show your model to be wrong, but... I am only trying to explain what we actually examine and observe in studies on natural populations, which flies in the face of what you are proposing. If you only want to discuss hypothetical experiments and tell us what the hypothetical results should be, then this will never move forward. Unless, of course, you have some real data to support your position. It has not been forthcoming as of yet.HBD

That doesn't match any understanding of genetic drift I have ever heard of. It doesn't even make sense.You mentioned once that you thought of drift as random selection, and that is a better description of drift than the above. Drift removes individuals from a population by random events regardless of the individual's fitness. Drift happens within populations - all populations, not just daughter populations.The parent /daughter split would NOT be considered genetic drift. After separation, the two populations could experience genetic drift at different rates and to different effects, but the split itself is not drift.HBD

Separation need not occur immediately after a trait appears. Your scenario is artificial and designed to require a breeding like situation.You are definition of evolution is too limiting. Many other scenarios exist. Separation need not occur immediately even if some animals have traits that make them somewhat more fit than their peers. If for example, a single mutation causes a animal to develop a tusk that provides some advantage, exactly whom is that animal going to mate with? Obviously for some time, the only viable mates will be in the existing population.There is simply no reason that at separation the new population must be less diverse than was the original population at the time of its forming.There are lots of examples of extremely diverse animals wandering around together. Why is it necessary to have complete species isolation during the selection process? I wouldn't expect that situation to be the only possibility.

To be clear. I did not claim that you "thought" anything. I pointed out that your argument as well as your definition of genetic diversity ignored mutations that made new genes. I don't claim new alleles for a gene to be something inconsequential. What you think is contrary to the evidence. We know that mutations create genetic diversity, and you've been given examples, which in other discussions you've labelled as "flukes".Flukes are rare things that actually have happened. So even your statements about this issue contain self-contradictions.My contention is that if I gather up all of the admissions you've made in this thread and a couple of the others, I could put together a pretty convincing argument that your position is wrong.Edited by NoNukes, : No reason given.

Again you have only increase in genetic diversity in mind, which would be reduced by microevolution by population splits anyway, if getting a new speciies is still the goal of evolution; so as I keep saying it doesn't really matter if mutations do what you say they do or not.Or let me just ask:So here you've got new genetic diversity. Tell me how you are going to get that new diversity to a new species? Edited by Faith, : No reason given.

Multiple points of new diversity.Surely, anyone with a shred of imagination can figure out how to do selection on one point of diversity without losing all of the new points of diversity.Further, even after the species is created, mutations can add more diversity. You are focusing strictly on the event that isolates mating partners and ignoring what can happen before and after.Edited by NoNukes, : No reason given.Edited by NoNukes, : No reason given.

I have to post separately to complain about this. Evolution does not have a goal. Evolution is a result of natural processes that do not have a mind, intentions, or arms and legs.Speciation is one important outcome of evolution.

Your scenario is possible, but is not a required outcome.Multiple individuals may inherit the trait in combination with various other traits. We don't have to throw out the individuals that don't look like a poodle as we would do when breeding. There is no real reason for their to be a limit on how diverse you can be with the new trait until there is no mixing of old types with new types. After gene flow between groups stops, new diversity can still be added by new mutations in each group.

One cannot get a pure bred line of dog and maintain diversity ... this is true. If you keep breeding for a specific trait, you will eventually destroy the genetic line through inevitable inbreeding.
But you also cannot equate evolution with the breeding of dogs for specific traits. Although it shows how selection proves evolution, it's not how things happen in the "real world".
Selective breeding of dogs or other domestic animals is not "survival of the fittest". It is unnatural selection of traits desired by the owners. Most modern dogs would not survive in the wild, and would not be able to pass on their genes.Evolution DOES cause diversity, due to the environmental conditions that cause different survival traits to surface and be passed on. Only when on group evolves too far to "mingle" with other offshoots of teh parent species does a "new" species develop.

How does evolution arrive at what is called a new species? I know only one way: by forming daughter populations that bring out new traits or phenotypes because of their different allele frequencies, and a series of such population splits would get there sooner. And this process requires reduction in genetic diversity, variation or whatever the proper term is.Nothing has been said to indicate that there is any other way for speciation to occur.And the official definition to be found at Wikipedia is' Adding genetic diversity to a population by any means at all, migration or mutation or whatever, adds new phenotypes but doesn't do anything to make a new species out of them. That takes reproductive isolation of a particular set of those traits breeding together over some generations. It doesn't matter if the diversity is added to a large population that subsequently splits, or if it is added at the end of a series of populations, to a subspecies or new species, the same process has to occur for the formation of further species: reproductive isolation of new traits breeding together, and that will reduce genetic diversity (the number of allelic possibilities)which makes further evolution impossible. So you get new diversity and the same thing has to happen and around we go. Evolution, meaning macroevolution, meaning evolution as understood by the Theory of Evolution, really is impossible.I do think that is obvious if you just think it through.Whatever the proper term is for what I've been calling genetic diversity, what I have in mind is the number of allelic possibilities for further variation in the population, variation which is microevolution. I don't care what you call it.There are only two measures I can think of that should indicate increase or decrease in the number of allelic possibilities from parent to daughter population, and those are alleles per locus and heterozygosity. I am thinking only of measuring these at the loci for the characteristic tratis of each population and not the entire genome. If even this much is logistically impossible, then I can't see any way to prove my claim one way or the other. End of experimental project.So: I'm using the term evolution to describe active microevolution which as far as I can see only occurs in a subpopulation created by some kind of selection, either adaptive or random, which would have new allele frequencies which would form new traits with some degree of reproductive isolation. (I've thought of the random selection of genetic drift as a version of this which occurs completely within the parent population, but HBD says no. It might be good to have a discussion about genetic drift then.)Evolution in action is therefore ONLY microevolution, and it has a natural end point brought about by the loss of genetic diversity (or allelic possibilities) necessary to the creation of new phenotypes. If this leads to "speciation" it also leads to genetic depletion, which makes further evolution impossible.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

When I use the term evolution I'm talking about the processes that bring about new phenotypes, I am not talking about the Theory of Evolution.Actual evolution brings about phenotypic diversity, but I'm talking about genetic diversity which does NOT increase, it decreases. --In reality, though not according to the ToE.Edited by Faith, : No reason given.

Okay, maybe I am out of my depth. I am not a genetic scientist. So, the following flight of thought is based on what I've read and how I processed it.
A parent gives it's offspring a genetic advantage, and that offspring becomes a parent. It produces offspring of it's own that strengthen the trait. which continues until a new genetic advantage arises. However, the offspring have separated and there are now several offspring spread over a greater area. The genetic advantages given to successive generations will differ from one area to the next, creating greater variation. The more variation in environment, the more variation will arise in genetic advantage.
Generations later, offspring cross paths. If they have not genetically changed enough, they will still be able to breed, refreshing the gene pool. If they've changed too much, they are now separate and "new" species that cannot breed across the genetic gap.
If you continue to expand this ... genetic diversity grows, it doesn't shrink.Where does this logic fail?