Evolution Requires Reduction in Genetic Diversity

I think the problem here is that there is no term for one kind evolving into another kind. For a YEC, anything less than that is micro-evolution. So even if we produce two sheep that cannot mate with each other, those animals are still sheepy kind.Edited by NoNukes, : No reason given.

You are just trying to define yourself into being right. If a daughter population has lost the ability to interbreed with the parent population and is distinctly different from the parent population, then we would recognize it as a separate species. Calling it a subspecies that has lost its ability to interbreed is just word play.So this "end point" is the point where a fish would grow legs or a dinosaur would sprout wings right?Let's try this... Population A has the alleles R, Q and S. These alleles are co-dominant so that combinations produce intermediate phenotypes. The genotype combinations would be: RR, RQ, RS, QQ, QS, and SS. 6 combinations of alleles exist in this population.Now suppose that population B splits off of population A and is isolated. However, it is a small population so not all of the alleles are represented in the new population; only alleles R and Q are represented in the new population. So the combinations in population B are: RR, RQ and QQ - only 3 allele combinations are in the new population.So... a reduction in genetic diversity right? 6 combinations in the original and only 3 in the daughter. So far so good.Now these populations breed among themselves and their alleles get all mixed up and shuffled around. So now there is:population A: RR, RQ, RS, QQ, QS, and SSpopulation B: RR, RQ and QQWait... what has changed? The same allele combinations. Hmmm... Also note that the combinations in the daughter population already exist in the parent population. Kinda disappointing, but OK, still loss of genetic diversity.Now imagine there is a mutation in allele R in population B, lets call it r. There is a deletion of a small section of DNA, creating a stop codon and a truncated protein. This protein is non functional, but it is also recessive since the other alleles are dominant. So as long as it is paired with a dominant allele the organism is viable. Thus this recessive allele can "hide" in heterozygotes and spread through the population.So now we have alleles R, Q and r in the daughter population. So now the allele combinations in population B are:RR, RQ, Rr, QQ, Qr (we can assume that rr will be non-viable) - 5 allele combinations.Now what happens if there is another mutation? Let's say that allele Q has a substitution and this substitution changes the amino acid coded for but doesn't change the function of he protein. We can however detect this allele when we sequence it. Let's call it Q*. So now the combinations we have are:RR, RQ, Rr, RQ*, QQ, Qr, QQ*, Q*r, Q*Q* 9 allele combinations!We see no phenotypic change but there IS an increase in genetic diversity. At least I would call this:RR, RQ, Rr, RQ*, QQ, Qr, QQ*, Q*r, Q*Q*more genetically diverse than this:RR, RQ, RS, QQ, QS, and SSMaybe you say it doesn't constitute an increase in genetic diversity because it doesn't change the phenotype. Oh wait, you are talking ONLY about genetic diversity not phenotype diversity. Hmmm...I know, I know...HBD

No. Definitional word play is a lot of what evolution does. Call it a species, or call it macroevolution, which is another definition used for it, and you can deny its compromised genetic condition. If it's lost enough genetic diversity to be seriously compromised, it's the point where no further variation is possible. At the very least, LESS variation is possible. That's how it comes to the end of evolution.My eyes need a serious rest so I'll try to get back later to posts I'm just touching on now.

I guess it was more wishful thinking or hope for the cheetah. They look so powerful with their great speed. Poor babies, I don't want them to be having a hard time.No, we aren't in danger of dying yet though everything is tending in that direction. Humanity still has a very large genetic diversity.And there are still large stable populations of animals with high genetic diversity. Unless that's just more wishful thinking. I hope not.It's only where there is a serious reduction in numbers so you get seriously reduced genetic diversity that creatures become endangered. But conservationists apply themselves to that very problem. Edited by Faith, : No reason given.

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But if speciation is not really a new species but just a subspecies that has lost the ability to interbreed with other subspecies, and if as a matter of fact it possesses reduced genetic variability, then it is sheer illusion to call it speciation.

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Faith, I understand that it is important for you to refuse to accept that you believe in macroevolution - independent of the actual meaning of the word. But in doing so you only betray the fact that you are the one who believes in word magic.But saying that your irrational hate of a word dictates the correct usage of other words - even to call a correct usage "sheer illusion" is the height of arrogance. That is, even if your description was entirely correct for any single example it would still be a new species.And, of course, through genetic drift alone an isolated population will certainly accumulate genetic differences at the level of sequences. And, over time, it is very likely that it will acquire new traits through mutation too. It is even likely that these changes are the cause of the inability to interbreed with the parent population.

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Which is not based on any kind of evidence of relatedness between the different groups but is only an appealing mental construct imposed on the facts.

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The nested hierarchies ARE facts. Facts you don't like. But simply making assertions will not overcome facts.

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And they do, through normal microevolution as I've been laboriously describing it, which reaches a natural end point where macroevolution should begin but can't because of genetic depletion.

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I think you've repeated your assertions often enough. But that is hardly a convincing argument. You need evidence. You need to deal with the objections. You need alternative explanations for the evidence for large-scale evolution rather than trying to pretend that the evidence doesn't exist. If all you can do is to keep repeating your assertions then you don't have a case.

Probably sheepish.

I read this and can't help but think of the insect world. Genetic changes have created such a vast array of insects, many of which are (in many cases) MUCH more complicated than mammals and other vertebrates. A good example is the lightning bug. No mammal has developed bio luminescent capabilities.
But the VAST number of insect species within a family, like the beetles, proves that different species can, and do, arise from parent populations. Not only arise, but thrive, adapt and modify into even more offspring populations that become unrecognizable from the ""grandparent" populations.

Please see my Message 795 where I already ruled on this point. "Speciation" already has a definition, please do not attempt to redefine it. You can argue that speciation never happens, even that it is impossible, but you cannot redefine it. I will always rule against the redefinition of existing terms. If you would like to discuss the terminology of evolution please propose a new thread over at Proposed New Topics. This thread will be using existing terminology. New terms can be introduced as long as they are clearly defined.

Losing the ability to interbreed is the definition of speciation, and this is why people are complaining that you are trying to redefine the terms.Personally I don't see what the problem with new species is for creationist\creationism, as no-one claims that "kinds" are species as far as I know. We have discussed this before, and I have brought up cladistics before. At it's most simplest level, Cladistics is defined as:

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noun, Biology, (used with a plural verb)
1. classification of organisms based on the branchings of descendant lineages from a common ancestor.

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You can start with the "original" common ancestor from the day of creation, or from the "kinds" preserved on the ark, as a creationist, or you can start with species alive today and work your way back to see how far it goes (does it go all the way to "original" breeding populations of archaic bacteria?), as a biologist. The process is the same -- microevolution and speciation. For example:

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... The organisms are placed into charts called cladograms that are divided into clades, groups that share an ancestor.

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An example of a cladogram

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This could be the "bear kind" clade for a creationist, or part of the overall tree of life for a biologist. Whether or not it possesses reduced genetic variability, speciation is defined by the loss of ability to interbreed. Complaining about a word being used in a science the way scientists defined it is sheer pointless madness -- all you will do is cause misunderstanding when you use words to mean different things than the say other people are using them.This is why Percy is asking you to clarify your position.Consider how many times you complain about people not understanding your position, and then consider that it is because of the way you have said things and the words you use. Again, speciation (the loss of ability for two subpopulations to interbreed) has been observed and the formation of a clade at its most simplest level is

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                         ^ speciation
                        / \
                       /   \

This clade includes the parent population and the two genetically incompatible daughter populations. But it doesn't matter whether you call them species, subspecies, subsubspecies or whatever -- it is a fact that this occurs, as it has been observed. They are actual factual daughter populations that have actual factual evolved from a parent species and are actual factual genetically incompatible. Does that meet the scientific definition\usage of speciation? Yes: ergo speciation has occurred, no interpretation needed. Again, why? This says nothing about whether genetic diversity increases, decreases or stays the same. This is the way scienced defines (micro)evolution - which you accept occurs.Whether or not it possesses reduced genetic variability afterwards, evolution is defined by the changes in the composition of hereditary traits, and changes to the frequency of their distributions. Complaining about a word being used in a science the way scientists defined it is sheer pointless madness -- all you will do is cause misunderstanding when you use words to mean different things than the say other people are using them.This is why Percy is asking you to clarify your position. Exactly. Microevolution is the only evolution that occurs. It is how species change over time and it is how speciation occurs when daughter populations lose the ability to interbreed when microevolution in isolation from each other results in genetic incompatibility. And this is where you run into trouble using words to mean something else than the way it is defined in science: the formation of genetically incompatible daughter populations IS macroevolution to scientists, so we know that macroevolution occurs because this has been observed.Can you tell me what you mean by "macroevolution" (presumably something different from the scientific usage\definition)? Yes, Faith -- reading it and disagreeing with it does not mean I haven't read or understood it, just that I don't agree.And when you say things that are contradicted by facts I will continue to point that out.

And then there is the issue of cryptic species -- populations that look alike but can't interbreed. The malaria carrying mosquito is an example: when they were looking for biological control methods they discovered that one kind did not carry the bug and the other did, even though they looked the same. One population bred at dawn and the other at dusk, and a slight variation in the genitalia prevented interbreeding.Species complex - Wikipedia

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... terms sometimes used synonymously but with more precise meanings are: cryptic species for two or more species hidden under one species name, sibling species for two cryptic species that are each others' closest relative, and species flock for a group of closely related species living in the same habitat. ...

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... . It may represent an early stage after speciation, but may also have been separated for a long time period without evolving morphological differences. Hybrid speciation can be a component in the evolution of a species complex.

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Enjoy

So you've added a couple of neutral or nonfunctioning mutations and get greater genetic diversity. So what else is new? If it doesn't change the phenotype you think you've proved something?For one thing the scenario is totally hypothetical. It may never have happened and never will happen.And if it doesn't change the phenotype how is it contributing to the formation of the new species? I'm arguing that the processes that bring about the new phenotypes are what reduce genetic diversity. If genetic diversity or variability or whatever you want to call it does increase, unless it becomes subject to the processes that bring out the new phenotypes it's not part of my scenario anyway. Presumably you want increased genetic diversity as a basis for further evolution/change in the population. What good is increased genetic diversity that does nothing? Are you going to defeat my argument that way?Isn't the point to prove that it contributes to the evolution that's bringing out the new traits, since my argument is that this is what reduces genetic diversity? And I also argue that increased gene flow or genetic diversity that DOES contribute new traits nevertheless then becomes subject to those processes that decrease it in order to make a sibspecies from them. Edited by Faith, : No reason given.

I don't know yet if I need to continue to argue against the definition of speciation, but I'm leaving it for now. So inability to interbreed just IS the definition of speciation.I still have the question, What if speciation brings about new species that are always genetically less diverse or variable than the populations that preceded them? Doesn't that imply LESS ability to evolve and doesn't that imply that it doesn't really fulfill the evolutionary requirement assigned to it in its official definition: That is, if new biological species CAN'T arise from this point due to genetic impoverishment, what then? Sure, but if it has less genetic variability with which to evolve beyond this point, how is it "the evolutionary process by which new biological species arise?" You know you have a new population that can no longer interbreed with others and you are calling that macroevolution, which implies the ability to continue to evolve beyond that point. I think evolution comes to a natural stopping point with the loss of genetic diversity brought about by the very processes that produce new species. I think of this as the outer limit of the Kind beyond which no further change/variation/ evolution is possible for sheer lack of the genetic stuff needed for it. It's more of a functional definition than a category definition. If there is a natural ending point then you can never get a new "species" or the species you do get is a dead end in itself and not a platform for further evolution.

I'm trying not to redefine it but to discuss it in relation to my argument, such as to answer RAZD, involves describing what I think really happens at that point. If that's redefining it then I guess I'll have to think about a new thread.

You keep speaking of this lack of genetic material, or running out of alleles. But you're dealing with a set of combinations that is virtually limitless. The combination of different genes from two parents give rise to an offspring with a "new" set of genes. It renews the possible alleles combinations. True, some carry on, those that reinforce positive reactions to current environments, but the genome is capable of renewed changes.
Every succeeding generation has as many possibilities for change as the parents did ... diversity continues.

HBD:I've briefly breviewed a bunch of your posts and tried to do what you asked with messages 723 and 754, despite your barrage of accusations, and I just can't make enough sense of your examples to respond to them. I'm sure as you say it seems to you it shouldn't be a problem but it is.And I do think that if you can't respond to my argument on MY level, the fur and tails level, and formulate your objections to my argument on that level, which is the only kind of example I've used throughout the thread, and which everybody else was addressing too, it's way too soon to expect me to switch gears and try to deal with your charts and fungi. It's too foreign to my thought processes. I CAN'T make sense of your chart and I can't make ANY sense of your fungus example. I really can't.