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Author
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Topic: can some aspect of Darwinism be falsified?
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Zachriel
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Member # 1793
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posted 22. May 2006 21:02
Shi: "I just want to confirm with you guys the position of Darwinism in this respect. is it true that Darwinism says that a population become transformed into a new species together as a group?"
Darwin didn't propose a complete mechanism of speciation, but today there are several known mechanisms of speciation.
The most common is probably allopatric speciation. That occurs when a population is divided by geographical barriers. The separate populations tend to diverge stochastically, and even when reunited may not exchange genes due to biological or behavioral incompatibility.
Sympatric speciation can occur when populations diverge due to behavioral adaptations related to specialization. This type of divergence is often enhanced by reinforcement. Sometimes speciation can occur suddenly with polyploidalism, especially in plants. Not all polyploids are completely isolated from the parent strain, though.
Keep in mind that divergence leading to speciation is often an on-going or even an oscillating process. Populations may diverge for a while, then hybridization may reverse the process.
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John A. Davison
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Member # 1425
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posted 23. May 2006 02:06
I presume Zack can document these Darwinian claims?
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John A. Davison
Member
Member # 1425
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posted 23. May 2006 09:34
How about just one documented example?
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John A. Davison
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Member # 1425
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posted 23. May 2006 16:16
Here are a couple of other unanswered challenges that I have presented on internet forums like this one.
Name any two species fossil or extant and present any evidence from any source that one is ancestral to the other.
Name a mammalian species younger than Homo sapiens.
Present evidence that any new species has evolved in historical times. This is of course a variation of the first one. We see the products of a long past evolution and not evolution in progress as the Darwinians still blindly insist.
Since none of these challenges have been answered or even acknowledged, I have naturally drawn the only rational conclusion. Evolution is no longer in progress and Homo sapiens was the ultimate product of a planned sequence. In other words, evolution was "prescribed."
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Scott
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Member # 1222
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posted 23. May 2006 17:38
quote:
The confusion occurs because the molecular clock is not defined by the rate of mutation, but the rate of fixation which varies according to population size.
What is the relevance of neutral mutations to the "molecular clock?"
What is the difference between the rate of mutation and the rate of fixation for neutral mutations?
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Christopher D. Beling
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Member # 723
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posted 23. May 2006 17:57
I agree Scott; According to Kimura's neutral theory the rate of fixation is the same as the rate of mutation, and (amazingly) this is independent of population size.
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John A. Davison
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Member # 1425
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posted 23. May 2006 22:33
Population size never had anything to do with evolution either. Neither then did population genetics because that is nothing but the distribution if alleles in sexually reproducing populations. None of these ever had any role in a purely emergent, "prescribed" evolution, an evolution no longer in effect. Sorry about that, but prove I am wrong.
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Zachriel
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Member # 1793
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posted 23. May 2006 22:45
Scott: "What is the relevance of neutral mutations to the 'molecular clock'?"
Neutral mutations are fixed by stochastic processes. Mutations that are not neutral are subject to selection and possibly rapid change.
Scott: "What is the difference between the rate of mutation and the rate of fixation for neutral mutations?"
The rate of mutation is the rate by which a mutation occurs in a given replication. Fixation refers to the mutation becoming the predominant allele in the population at large. For a *specific* neutral mutation, fixation is heavily dependent on population size according to implications of a very simple mathematical relationship, the Hardy-Weinberg Equation (1908).
Christopher D. Beling: "According to Kimura's neutral theory the rate of fixation is the same as the rate of mutation, and (amazingly) this is independent of population size."
That is correct. Though a specific mutation is not likely to fix in a large population, there are mutations of some sort happening throughout the population. Hence, Kimura's original neutral theory hypothesized that neutral fixation would be related to generational time (as per the relevant mathematics).
Since then, advances in empirical observations has led to advances in theoretical understanding. It turns out that "neutral" is a relative term and has led to various "nearly neutral" hypotheses, such as by Ohta and Takahata.
Basically, in a small population, a slightly detrimental mutation may reach fixation before being deselected. These ideas are still being studied, but computer modeling and empirical predictions support the basic idea.
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Kimura M: The Neutral Theory of Molecular Evolution Cambridge: Cambridge University Press 1983.
Ohta T: Synonymous and non-synonymous substitutions in mammalian genes and the nearly neutral theory. J Mol Evol 1995
Takahata N: On the overdispersed molecular clock. Genetics 1987
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Scott
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Member # 1222
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posted 24. May 2006 11:38
quote:
I agree Scott; According to Kimura's neutral theory the rate of fixation is the same as the rate of mutation, and (amazingly) this is independent of population size.
Thanks Chris. The relevance of the questions seems to be completely lost on Zachriel.
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Melvin H. Fox
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Member # 1684
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posted 24. May 2006 15:24
Zach, I would be very much interested in any documentation you could provide to answer John. Is there none? Could it be that the hypothesis of speciation via natural selection has not been tested; or if tested, then it has failed?
You say the mechanisms for speciation are known [esp. allopatric speciation]. How are they known?
-Mel
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John A. Davison
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Member # 1425
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posted 24. May 2006 19:28
Melvin
The wonderful thing about natural selection is that it cannot be tested because nature is not a laboratory. Nevertheless, every concerted laboratory attempt has failed to transform any species into a new member of even the same genus. The last serious attempt was by Theodosius Dobzhansky with Drosophila and it is very much to his credit that he admitted failure. The bizarre thing is that he remained a devout Darwinian nevertheless, one of the great mysteries of the evolutionary literature.
Dobzhansky was a fine geneticist and I am convinced that if he had remained in Russia with his mentor, Leo Berg of all people, we would today be discussing Bergian rather that Darwinian evolution and natural selection would now be a thing of the distant past. Its only role now as always was and still is to maintain the status quo.
Leo Berg knew that. So did Reginald C. Punnett and Pierre Grasse and so do I. Neither allelic mutation nor sexual reproduction ever had anything whatsoever to do with creative evolution. The silence with which my several challenges has been met is testimony to that inescapable reality. Why others do not realize that remains one of the great mysterues of the evolutionary literature. My only explanation is:
"We seek and offer ourselves to be gulled."
Montaigne
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Christopher D. Beling
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Member # 723
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posted 24. May 2006 21:24
quote:
Darwin didn't propose a complete mechanism of speciation, but today there are several known mechanisms of speciation.
Zach, I must refer you to a review article by Sergey Gavrilets [Evolution 57 (2003) 2197-2215] where he says:
quote:
Instead of a sound mathematical theory of speciation, there is what I can only interpret as (justifiable) frustration among both empiricists and theoreticians with the theoretical speciation research ---Theoreticians Kirkpatrick and Ravigne (2002) talk about the “balkanization” of the theory of speciation and the absence of clear and general results worthy to be included in the textbooks - - What is missing in the theoretical speciation research are general and transparent analytical results comparable to those in other areas of theoretical population genetics and ecology.
Gavrilets tries in his paper to provide a way out, but I am far from convinced. He shows how under some rather contrived allelic conditions that populations can get reproductively isolated. This is not the same thing as speciation though – as today we have many examples of separated populations – but they are all the same species because they capable of interbreeding (example the Galapagos finches and the Seagulls also Fernando's thread). There is the built in assumption that populations once reproductively isolated will change into different species.
The empirical observation of "Punctuated equilibrium" is often put forward as a “theory” of speciation, but it is no such thing because it is quite at variance with what we know in population genetics (a theory known to be quite well validated). If a small group diverges from a main population (allopatric “speciation”?) then it will undergo a faster fixation of mutated genes. Some of these are assumed advantagous (although there is no evidence that such occur mutations occur) – but these positives (even if they did occur) would be totally swamped by the much larger number of deleterious mutations with this separated population becoming homozygous in lethal mutations. I don’t know how “punctuated equilibrium” can be taught as a theory? I am sorry to say that I think this is only wishful thinking. Chris
[ 24. May 2006, 21:42: Message edited by: Christopher D. Beling ]
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Bruce Fast
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Member # 924
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posted 24. May 2006 22:31
This thread has taken an intriguing new twist. However, PB, I am hoping that you will renew the discussion about the redundant H1s. I am quite convinced that you have an extremely valid case with the H1s.
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John A. Davison
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Member # 1425
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posted 25. May 2006 07:00
Here is an idea. Why not introduce a thread based on my May 23 16:16 post in which I issued some challenges to the Darwinian position? I have always been willing to defend everything I have either published or presented on internet forums like this one. Typically that opportunity has been denied me by the time honored ploy of changing the subject and pretending that I, like all my sources, simply do not exist. That seems to be happening again here. There was a time when that was not so at "brainstorms" as anyone knows who is familiar with my activity here in the past.
So I request that a thread be introduced enabling me to continue to present the evidence that chance, the cornerstone of the Darwinian paradigm, never had any role whatsoever in creative evolution, a phenomenon I am convinced is no longer in progress. Is anyone interested in introducing such a topic?
I would introduce such a thread myself but I don't know how and it would seem presumptuous of me if I did.
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John A. Davison
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Member # 1425
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posted 25. May 2006 10:23
The ball is now squarely in the court of the management of "brainstorms" and those who participate here.
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