A test for claimed knowledge of how macroevolution occurs

Faith writes: You say you can demonstrate mutations. But you don't, and can't.

Why do you say blatantly wrong things that you must know are wrong and that contradict other things you've said? If this isn't what you meant then go back and edit it, maybe to say that your talking about beneficial mutations or whatever it is you actually meant, or maybe quote what you're responding to to set the context. We know you can't actually mean that we can't show mutations exist because you're on record in post after post as acknowledging that mutations exist.

Anyway, probably the best way to prove my contentions would be in the laboratory experiment I've often suggested. Mice are always a good choice for their size and habits but you want to start with a population that has a pretty high genetic diversity and I wonder how much diversity remains in the wild populations of mice. Maybe enough.

You're doubting the genetic diversity of wild mice? You don't say which mouse species, and population estimates vary. The most common species is the house mouse with a population often estimated to be roughly the same as people. Their genetic diversity must be enormous.

Continue until the latest daughter populations run out of genetic variability.

Unless the experimenters place the mice in environments that subject them to substantial selection pressures, or if the mice populations are small, reductions in genetic diversity would be unexpected. Though naturally a laboratory population could not have as much diversity as the hugely larger world-wide mouse population.

--Percy

Lengthy cut and paste warning. You can also read online and see the pictures that go with the text.

I copied them off the Google page on "processes of evolution." They are from the Cal Berkeley website on evolution.

Thanks. One of my favorite sites for teaching about evolution. The full listing is:

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Mechanisms: the processes of evolution

Evolution is the process by which modern organisms have descended from ancient ancestors. Evolution is responsible for both the remarkable similarities we see across all life and the amazing diversity of that life — but exactly how does it work?

Fundamental to the process is genetic variation upon which selective forces can act in order for evolution to occur. This section examines the mechanisms of evolution focusing on:

• Descent and the genetic differences that are heritable and passed on to the next generation;
  
• Mutation, migration (gene flow), genetic drift, and natural selection as mechanisms of change;
  
• The importance of genetic variation;
  
• The random nature of genetic drift and the effects of a reduction in genetic variation;
  
• How variation, differential reproduction, and heredity result in evolution by natural selection; and
  
• How different species can affect each other's evolution through coevolution.

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So you left off the part about genetic variation (Mendelian genetics plus mutations) being fundamental to evolution and how the ecology (different species affect each other's evolution) affects selection.

May I suggest that you continue on at least to the next two pages?

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Descent with modification

We've defined evolution as descent with modification from a common ancestor, but exactly what has been modified? Evolution only occurs when there is a change in gene frequency within a population over time. These genetic differences are heritable and can be passed on to the next generation — which is what really matters in evolution: long term change.

Compare these two examples of change in beetle populations. Which one is an example of evolution?

1. Beetles on a diet

   Imagine a year or two of drought in which there are few plants that these beetles can eat.

   All the beetles have the same chances of survival and reproduction, but because of food restrictions, the beetles in the population are a little smaller than the preceding generation of beetles.

2. Beetles of a different color

   Most of the beetles in the population (say 90%) have the genes for bright green coloration and a few of them (10%) have a gene that makes them more brown.

   Some number of generations later, things have changed: brown beetles are more common than they used to be and make up 70% of the population.

Which example illustrates descent with modification — a change in gene frequency over time?

The difference in weight in example 1 came about because of environmental influences — the low food supply — not because of a change in the frequency of genes. Therefore, example 1 is not evolution. Because the small body size in this population was not genetically determined, this generation of small-bodied beetles will produce beetles that will grow to normal size if they have a normal food supply.

The changing color in example 2 is definitely evolution: these two generations of the same population are genetically different. But how did it happen?

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Mechanisms of change

Each of these four processes is a basic mechanism of evolutionary change.

Mutation

A mutation could cause parents with genes for bright green coloration to have offspring with a gene for brown coloration. That would make genes for brown coloration more frequent in the population than they were before the mutation.

Migration

Some individuals from a population of brown beetles might have joined a population of green beetles. That would make genes for brown coloration more frequent in the green beetle population than they were before the brown beetles migrated into it.

Genetic drift

Imagine that in one generation, two brown beetles happened to have four offspring survive to reproduce. Several green beetles were killed when someone stepped on them and had no offspring. The next generation would have a few more brown beetles than the previous generation — but just by chance. These chance changes from generation to generation are known as genetic drift.

Natural selection

Imagine that green beetles are easier for birds to spot (and hence, eat). Brown beetles are a little more likely to survive to produce offspring. They pass their genes for brown coloration on to their offspring. So in the next generation, brown beetles are more common than in the previous generation.

All of these mechanisms can cause changes in the frequencies of genes in populations, and so all of them are mechanisms of evolutionary change. However, natural selection and genetic drift cannot operate unless there is genetic variation — that is, unless some individuals are genetically different from others. If the population of beetles were 100% green, selection and drift would not have any effect because their genetic make-up could not change.

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Note each cause of changes to the gene pool are discussed in greater detail in following pages. I strongly recommend you take the time read them all. If you have any questions feel free to ask.

The better you understand the scientific model the better able you should be to discuss it versus your model.

Enjoy

Good grief, HBD

You could try actually reading posts before responding to them since I wasn't say in phenotypic diversity disproves your argument. I was only illustrating how important diversity is to biologists. The main point of my argument was genetic based.

HBD

Fine, I'll go back and read it again eventually, but why tell me about the importance of (phenotypic) diversity anyway, that's irrelevant to the whole discussion.

Reread the first part, then went on to this:

The short point here is that biologists have been studying diversity for a long time... and it is still a huge area of study. New genomic tools are allowing us to look at diversity on a whole genome level, not just at individual loci. If your model were correct, we would be finding that out. Instead, we are finding MORE and more diversity. We are discovering diversity we did not previously know existed (unculturable organisms for example) and how diversity looks at a genetic level - not just alleles, but whole genomes.

...have been studying DIVERSITY.. So? ...genomic tools are allowing us to look at DIVERSITY... So? YOU ARE STILL TALKING ABOUT PHENOTYPES. You are looking at the DIVERSITY on a whole genome level.... What ARE you talking about? You seem to be talking about looking at phenotypic diversity in the genome. Or I have no idea what you are talking about. And I really **** having to address bacteria, so I may not even read the rest of your post anyway. The first part doesn't give me any encouragement to think the rest will be any more illuminating.

Edited by Faith, : No reason given.

And now I've read through the rest of the post and it's incomprehensible to me sorry. You keep using the word "diversity" but you never say "GENETIC diversity" and I really have NO idea what you are talking about but I suspect you are still talking about phenotypes (eating leaves and waiting for opportunity to infect is on the level of phenotypes). Anyway I can't figure out what you are saying and that's the bottom llne.

Also, if you've read even a tenth of my argument you should know I'm talking about how populations develop into species by losing genetic diversity, and I don't focus on the genome level at all.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.

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...have been studying DIVERSITY.. So? ...genomic tools are allowing us to look at DIVERSITY... So? YOU ARE STILL TALKING ABOUT PHENOTYPES. You are looking at the DIVERSITY on a whole genome level.... What ARE you talking about?

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“Genomic tools” would be looking at the genome - the genes. Diversity on a whole genome level would be looking at the diversity of the genomes - comparing complete genomes, not, as HBD said, individual genes. It is all talking about genetic diversity.

Edited by Admin, : Minor punctuation fix.

Faith writes: I'm talking about their obvious appearance. I recall that in RAZD's Message 424 or the one before it, he describes the point at which a species becomes a species in terms that imply arrival at homogeneity, which has always been my criterion too.

Message 424 isn't from RAZD. I looked at the couple messages from RAZD before and after that one but couldn't tell which one you meant.

I'm not sure what you mean by "a species becomes a species." If you mean speciation then I don't think RAZD has ever said or implied that speciation involves homogeneity.

But maybe you're not talking about speciation. Had anyone else said "a species becomes a species" I would have assumed they really meant a species becoming a *new* species, but you don't believe speciation is possible, so I can't be certain what you mean.

The term homogeneous is ambiguous in this context. A better term would be diversity, or lack thereof.

Before that it starts with the founders all looking llke the homogeneous parent population.

Homogeneous is still ambiguous in this context, but if you mean parent populations must have low diversity, either genetically or physically, then that is incorrect.

Then there is a phase where there is a motley collection of different phenotypes scattered through the population, being brought out by the new set of gene frequencies.

Why do you think this?

After a few more generations they form their own new overall homogeneous appearance distinct from the original parent population.

Homogeneous is still not a good term in this context, and phenotypes can vary in ways that do not affect appearance (like the digestive tract differences in the Pod Mrcaru lizards), but you are correct that distinctly different phenotypes can emerge over the course of some generations.

Each individual has its own unique genome nevertheless, so that if some of them eventually form a new isolated population themselves they will contribute a unique set of gene frequencies to it that when reproductively blended together over some generations will produce yet another homogeneous population with characteristics distinct from all the others.

Isolated populations whose allele frequencies come to vary greatly from the parent population could result in very different phenotypes, but they would remain the same species, and RAZD was likely talking about speciation.

--Percy

Faith writes: Also, if you've read even a tenth of my argument you should know I'm talking about how populations develop into species by losing genetic diversity, and I don't focus on the genome level at all.

Why do you say this, since you don't believe speciation is possible?

Also, reducing allelic diversity cannot by itself create genetically distinct species. That would require mutation.

--Percy

No, it's the new gene frequencies that produce new species, and this entails losing the genetic material for the phenotypes that don't show up in the new population. THINK DOMESTIC BREEDING: how do you get a new breed? By getting rid of all the genetic stuff for other breeds. It's the same process in the wild, but the traits being developed into the new population are randomly selected. It's elementary if you'd bother to think at all. "Speciation" has nothing to do with any of this.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.

Faith writes: No, it's the new gene frequencies that produce new species,...

Why do you think this? Can you name any two species that cannot interbreed even though they have the same genes and chromosomes, the only difference being allele frequencies?

...and this entails losing the genetic material for the phenotypes that don't show up in the new population.

But you're not talking about creating new species by losing genes and chromosomes, which are the genetic material. You're talking about keeping all the genetic material and just changing the allele frequencies.

THINK DOMESTIC BREEDING: how do you get a new breed? By getting rid of all the genetic stuff for other breeds.

Have you ever heard of a breeder producing a new species?

It's the same process in the wild, but the traits being developed into the new population are randomly selected.

Traits in breeding are selected by the breeder while traits in the wild are selected by environmental selection pressures, not randomly.

"Speciation" has nothing to do with any of this.

Why is speciation in quotes? Are you using your own made-up definition?

--Percy

You obviously have no idea what I'm arguing but whatever.

Unless the experimenters place the mice in environments that subject them to substantial selection pressures, or if the mice populations are small, reductions in genetic diversity would be unexpected.

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The more individuals the better. But do your own lab experiment, you obviously haven't a clue to mine. Predict all you want based on your erroneous ToE beliefs, I intend to prove that you'll get genetic decrease with this method.

No selection pressures needed, and of course I want to start with as large a population as can be managed in a laboratory, and after its numbers increase quite a bit just letting them breed for a while, then I want to remove a smallish number of individuals to start the experiment proper.

I know what I'm doing although it's very clear you don't.

Though naturally a laboratory population could not have as much diversity as the hugely larger world-wide mouse population.

Certainly, we aim for the greatest genetic diversity we can get, that's all, the best we can do given the limitations of the lab setting. We might have to wait through some number of breeding generations to get a homogeneous appearance before the experiment proper can even begin. But I know you haven't a clue what I'm talking about so I guess I can't expect you to raise money to finance my project.

Edited by Faith, : No reason given.

I read the whole thing when I started out on the path I'm on. However, there's no harm in reading it again only it will have to wait.

Edited by Faith, : No reason given.

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You obviously have no idea what I'm arguing but whatever.

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It seems obvious that Percy has more of an idea than you do.

If closely related species differ in chromosomal arrangements and in which genes they have (i.e. one or both species have genes that the other does not) then it is clear that something more than differing allele frequencies is involved.

For instance even though horses and donkeys are close enough to produce (infertile) offspring, horses have one more chromosome pair than donkeys.