Freethought & Rationalism Archive

Doubting Didymus · 10-20-2002, 04:02 PM

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Frequency of alleles in populations just don't matter when you're interested in macroevolutionary differences between species or phyla.

Why not? What is molecular phylogeny?

I still require more clarification on your respective positions, Pz and Rufus. I hold that any factors that affect or otherwise 'drive' evolution must be effecting the heritable features of the population, otherwise the change is too temporary, and will revert. There are recognisable exeptions to only genes being heritable, such as endosmbiosis, but nonetheless heredity itself is the important factor.

RufusAtticus · 10-20-2002, 11:39 PM

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Originally posted by Doubting Didymus:

I hold that any factors that affect or otherwise 'drive' evolution must be effecting the heritable features of the population, otherwise the change is too temporary, and will revert. There are recognisable exeptions to only genes being heritable, such as endosmbiosis, but nonetheless heredity itself is the important factor.

Evolution still has happened even if the population "reverts." Even very heritable differences can "revert" after pertubation.

Peez · 10-21-2002, 02:09 PM

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pz:
I would suggest qualifying that as "as SOME biologists understand it". There's more to evolution than that, and many biologists approach it without ever even considering allele frequencies. Some are more interested in mechanisms of morphological change, or the history of change, or the geographic distribution of taxa...

I suppose that you are correct, in the same sense that SOME biologists accept that evolution has occurred. I don't know any biologist who thinks of evolution except in terms of changes in gene frequencies, but there may be such biologists.

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RufusAtticus:
Remember, I said I had a personal adversion to saying that I am "defining" evolution, when I feel I am describing it. If I were to define "evolution" it would go something like this.

Evolution (noun): A term used in the biological sciences that refers to the natural processes that account for the diversity of life.

Biologists define evolution as a change in allele frequency over time.

Some biologists do, and that is a good defination to use in High School textbooks. However, I it is plainly obvious that such a defination is very narrow and revisionistic. (In the history of science "evolution" preceeds "allele.")

How about this "High School textbook": Evolutionary Biology, Third Edition by Douglas J. Futuyma (Sinauer, 1998)

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evolution In a broad sense, the origin of entities possessing different character states of one or more characteristics, and changes in their proportion over time. Organic evolution, or biological evolution, is a change over time of the proportions of individual organisms differing genetically in one or more traits.

Certainly Darwin didn't know about alleles, he only thought in terms of inheritance. We now know that virtually all inheritance is by way of alleles.

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Sure, population geneticists, like me, work with evolution along those lines. However, other fields which study evolution, like paleontology, don't work with alleles.

Naturally, but that doesn't mean that they don't define evolution in terms of alleles. We often define a species in terms of ability to reproduce successfully, but we rarely determine a species in that way (and, obviously, paleontologists do not).

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Furthermore, change in allele frequency can't account for evolution by endosymbiosis.

I disagree. Just because you are harbouring an organism inside does not mean that you have evolved (at least, not by ther standard definition). Things like mitochondria have evolved from endosymbiotic bacteria by changes in alleles.

Peez

RufusAtticus · 10-21-2002, 03:11 PM

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Naturally, but that doesn't mean that they don't define evolution in terms of alleles. We often define a species in terms of ability to reproduce successfully, but we rarely determine a species in that way (and, obviously, paleontologists do not).

Remember, we define biological species in terms of ability to reproduce successfully. It along with morphological and folk concepts are helpful guides for choosing taxonomic species.

Yes many biologists do define evolution in terms of alleles, however many, like me, choose a more broad and classical defination/description.

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Just because you are harbouring an organism inside does not mean that you have evolved (at least, not by ther standard definition).

Which is a great example of why the standard defination is flawed and doesn't take account of the full range of biological phenomena covered by the concept of evolution.

Do you consider the change from sexual to asexual reproduction in insect populations by wolbachia infection to be evolution? That is one example not covered by allele-centric defination.

Doubting Didymus · 10-21-2002, 03:24 PM

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Do you consider the change from sexual to asexual reproduction in insect populations by wolbachia infection to be evolution? That is one example not covered by allele-centric defination.

Wait a minute, Although I am not certain of the specific case you cite (could you provide a link or reference?), is it not similar to a change from healthy human population to unhealty human populations due to staphlococcus infections? Is that evolution?

I would like the specifics of the wolbachia case you are talking about. Do the wolbachia benifit in some way from asexual hosts? If so, then are we not looking at an extended phenotype effect?

RBH · 10-21-2002, 06:21 PM

I'm finding this fascinating, especially pz's remarks. He is making pretty much the argument Paul Nelson (DI Senior Fellow) is making on ISCID at <a href="http://www.iscid.org/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=6&t=000197&p=1" target="_blank">http://www.iscid.org/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=6&t=000197&p=1</a>

RBH

Doubting Didymus · 10-21-2002, 06:35 PM

I do not see the resemblance.

pz · 10-21-2002, 06:40 PM

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Originally posted by RBH:
I'm finding this fascinating, especially pz's remarks. He is making pretty much the argument Paul Nelson (DI Senior Fellow) is making on ISCID at <a href="http://www.iscid.org/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=6&t=000197&p=1" target="_blank">http://www.iscid.org/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=6&t=000197&p=1</a>

Ick, no, pz certainly is not.

I am suggesting that there is more to biology and evolution than just DNA. However, that "more" is entirely natural and mechanistic, and no more proposes the hand of a designer than does the shape of a soap bubble.

Nelson is misusing those same ideas, which have been around since Goethe and D'Arcy Thompson (if not before) and are currently represented in the thinking of Lewontin and developmental systems theorists, to make a bizarre and unfounded claim about function preceding form as an argument for his goofy Designer.

Please do not confuse me with Nelson, ever. I find it very irritating.

Doubting Didymus · 10-21-2002, 06:46 PM

While you are here, pz, could you clarify your position in this thread a little for me? Are you proposing that some non-genetic factors are heritable, or that some non-heritable factors should be considered part of biological evolution?

pz · 10-21-2002, 07:04 PM

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Originally posted by Doubting Didymus:
While you are here, pz, could you clarify your position in this thread a little for me?Are you proposing that some non-genetic factors are heritable,

Yes. Of course they are.

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or that some non-heritable factors should be considered part of biological evolution?

Yes, that too.

There are factors other than the sequence of nucleotides in DNA that make substantial contributions to the form and function of organisms. They, too, are a part of our history and our makeup, and a theory that ignores them is deficient.

That does not mean that I think those other factors are green three-eyed aliens from the planet Xordax, or magical beings from outside the universe.

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10-21-2002, 06:21 PM	#56
RBH Contributor Join Date: Aug 2002 Location: Ohio Posts: 15,407	I'm finding this fascinating, especially pz's remarks. He is making pretty much the argument Paul Nelson (DI Senior Fellow) is making on ISCID at <a href="http://www.iscid.org/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=6&t=000197&p=1" target="_blank">http://www.iscid.org/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=6&t=000197&p=1</a> RBH

10-21-2002, 06:35 PM	#57
Doubting Didymus Veteran Member Join Date: Jul 2002 Location: East Coast. Australia. Posts: 5,455	I do not see the resemblance.

10-21-2002, 06:46 PM	#59
Doubting Didymus Veteran Member Join Date: Jul 2002 Location: East Coast. Australia. Posts: 5,455	While you are here, pz, could you clarify your position in this thread a little for me? Are you proposing that some non-genetic factors are heritable, or that some non-heritable factors should be considered part of biological evolution?

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