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Author | Topic: Micro v. Macro Creationist Challenge | |||||||||||||||||||||||||||||||||||||||
Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
CRR writes: However if you go back to my past posts you will find that I disagree with equating macroevolution to speciation. I have said that speciation could be the result of either microevolution or macroevolution; where the critical difference is whether the mutation adds a significant amount of new genetic information. Fruitful discussion requires agreement on definitions. As a starting point, here's the definition of macroevolution from Wikipedia:
quote: In your view, what's wrong with that definition? --Percy
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
CRR writes: The issue remains unresolved. How can fruitful discussion about micro and macroevolution take place while disagreement about their definitions remains? --Percy
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9
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CRR writes: That would depend on what changes were required to produce the differences and how you define micro/macro evolution....... This is why I originally said that you had arranged a "no win" challenge since you can make any assumptions you want and your definition of "microevolution" is so broad that such a scenario is permissible. From Message 1: Taq writes: ...Just for clarity, I am defining a microevolutionary change as a single mutational event (e.g. base substitution, insertion, deletion, transposon insertion, retroviral insertion, or genetic recombination) that is passed on to descendants. From the above it can be seen that your statement that Taq defined microevolution broadly is contradicted by his very words that you quote, which describe a rather narrow definition. These are the definitions of micro and macroevolution you offered in Message 183:
microevolution = changes in gene frequencies and trait distributions that occur within populations and species macroevolution = large evolutionary change, usually in morphology, typically refers to evolution of differences among populations that would warrant their plaecment in different genera or higher-level taxa (from the flashcard website Evolution Flashcards - Cram.com) Yours and Taq's definitions seem well within the realm of reconciliation. I continue to encourage you to reach agreement on the definitions.
Taq writes: If humans did evolve from a common ancestor shared with chimps, would you accept that as an example of macroevolution? That would depend on what changes were required to produce the differences and how you define micro/macro evolution. As I've said before IF the common ancestor had all the human genes that chimps lack (and vice versa) and IF you define genetic loss as microevolution THEN it could be entirely microevolution. No one's defining microevolution as genetic loss, and no one's calling human/chimp evolution from a common ancestor microevolution. Chimps have genes humans don't have, and humans have genes chimps don't have. That would seem the very definition of the accumulation of microevolutionary changes into macroevolution. --Percy
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
CRR writes: What I was trying to point out is that there is no single agreed definition for micro/macroevolution. All you've done is demonstrated a fact of life, that different people use different words and ways to define the same things.
Both the definitions I gave disagreed with your quoted definition for macroevolution. Not in any substantive way. If you think there are meaningful disagreements then point them out.
In message 1 Taq is trying to define microevolution as a single mutation event including almost any possible change, including an insertion of any size. The de novo appearance of a fully functional orphan gene as a single insertion would therefore be counted as microevolution. Technically yes it would, but that's an impossibly unlikely event.
Basically Taq allows himself a magic wand to accomplish any imaginable change in an arbitrary time. Taq has never said anything like this. --Percy
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
CRR writes: I am defining macroevolution as a gain of a statistically significant amount of genetic information. Macroevolution should constitute gains, losses and changes of genetic information. What do you consider a "statistically significant amount of genetic information"? Chimp and human genomes are percentagely similar in the high 90's. --Percy
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
CRR writes: Microevolution: genetic variation that requires no statistically significant increase in functional information. This is just a bunch of weasel words. If a mutation causes a new allele to be added to the gene pool of a population, then that is an increase in information. If via selection an allele disappears from the gene pool of a population, then that is a decrease in information. --Percy Edited by Percy, : "a mutation" => "an allele" in last sentence.
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
CRR writes: Did this gene evolve independently in 4 species but not in the other; or is it a gene that comes from a common ancestor and was lost in the chimp species? The latter.
Similarly there are genes in the chimp that have no homologue in humans but does have homologues in Orangutan, Gorilla, and Macaque. How would you explain this? Same way.
It seems that you find many genes that appear to be shared across several species but are missing from some. What does this indicate for how you view primate evolution? Primate evolution is an unremarkable example of evolution in action. --Percy
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
CRR writes: So the hypothetical common ancestor of humans and chimps would have had a few hundred more genes that either humans or chimps. That's how you've decided to measure amount of information in a genome? By counting the genes? The more genes the more information? Probably not valid. Anyway, you've made the error of paying attention to only one side of ledger, namely losing genes. Humans and chips have also acquired genes. Here's a chart that provides some gains and losses in number of genes:
So the hypothetical common ancestor of humans and chimps would have had a few hundred more genes that either humans or chimps. The chart says the opposite, that the common ancestor had fewer genes.
So this would be clear evidence of devolution. More genes doesn't mean better. The amoeba genome is a hundred times larger than the human genome, though I don't know how many genes it has. And the water flea Daphnia has 31,000 genes, exceeding the human count of 19,000 by quite a bit. And does the Daphnia genome contain more information than the human genome? At the rate you're figuring out how to measure information, you'll never be able to answer that question.
Creationists have been saying for some time that devolution, rather than evolution, is what we observe in nature. What we observe in nature is the process of evolution, which includes gaining and losing chromosomes, genes and alleles. The term "devolution" has no defined meaning within biology. --Percy
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
Meddle writes: I would agree with Taq, Percy and others that these were examples of gene loss in the ancestors of Chimpanzees since they branched off from a common ancestor with Humans. Actually, I didn't say that. It seems to me that other things being equal that something more symmetric should have happened, that humans and chimps should both have acquired and lost alleles and genes since the common ancestor. Here's some information I thought significant from the paper Comparing the human and chimpanzee genomes: Searching for needles in a haystack says:
quote: In other words, chimps may have lost genes that humans did not; duplications were 10 times more common in the human genome; and gene regulation by non-coding regions is a large unexplored area. There's a lot more in the paper. --Percy
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
I've been trying to track down more details about this chart:
I originally assumed the obvious, that the number in the right hand column is the number of genes, and that the red/blue numbers are the number of genes added/subtracted from the common ancestor. But now I'm not sure I trust this chart, for these reasons:
For these reasons, I'm disavowing this chart. But the original point made back in my Message 223 still stands. It's not valid to pay attention to "only one side of the ledger, namely losing genes." --Percy
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Percy Member Posts: 22502 From: New Hampshire Joined: Member Rating: 4.9 |
CRR writes: I've already said I'm not interested in answering the original topic because it is set up as a no win proposition. It was not a "no win proposition." Message 1 posed a simple question: why aren't two SNPs just nothing more than two microevolutionary events? I don't know what you're afraid of. An SNP is the most basic of microevolutionary events. Two SNPs would be two basic microevolutionary events. What is the problem with simply acknowledging this? --Percy
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