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Author | Topic: The End of Evolution By Means of Natural Selection | |||||||||||||||||||||||||||||||
Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
I want to have listened to the You Tube lectures before I go back there. I'm just taking a little break from my work now.
There's no rush is there? Cheers.
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misha Member (Idle past 4657 days) Posts: 69 From: Atlanta Joined: |
There is more than one way to skin a cat. . .
Along with the issues brought up by others concerning the frequency of mutations and their contributions to diversity, I find that Faith is oversimplifying possible solutions to selective pressures. A main crux of her argument is that natural selection will pare a population down to a single allele. This is not the case. Genes are not mutually exclusive, changes to one gene can result in changes to more than one trait. In order to see this more clearly we can look at the afformentioned frog tongues. Long tongues may be beneficial for catching some food sources but this does not mean that they are the best tongue type for catching all prey. A longer tongue would in turn result in more tongue weight. The increase in tongue weight without an equal increase in expellatory forces would result in a slower tongue. Although there will be an ideal tongue length vs tongue speed in this 2 variable set of equations, that ideal would be based on the frog's prey size, prey speed and average striking distange from prey. These factors could result in multiple solutions for the frog. A situation like this could easily result in speciation or just increased diversity.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
Can't see the relevance, don't see the relevance. Source of variations irrelevant to point.
Evidence that would convince me: evidence of an increase in genetic diversity AT speciation. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
The paring down to a single allele was strictly for purposes of illustration of the process I have in mind. I'm well aware that many genes are involved simultaneously in most changes in gene frequencies. The same processes I'm talking about would of course affect all genes at the same time, though at different rates, so it works fine to isolate a single allele just to describe what I'm talking about.
About the long tongue I was simply addressing that particular example as it was given by Pink Sasquatch on the original thread on this subject, as her example of natural selection working its way through a population over generations. There are always in nature lots of complicated things going on at one time, I'm just trying to single out one process among the many. There may be more than one gene involved in the tongue trait too, but for purposes of describing the particular process I have in mind a single evolving long tongue will do just fine. Edited by Faith, : comma
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Taq Member Posts: 10085 Joined: Member Rating: 5.1 |
From the opening post:
"My argument is that natural selection and genetic drift, all the processes that select or isolate a portion of a population, do bring about the change called evolution but also always reduce genetic variability, which is the opposite of what evolution needs." So you are arguing that evolution needs a source of new variation, a mechanism that introduces new alleles. Mutations do just that. Mutations refute your opening argument. Mechanisms which refute your claims would seem to be relevant.
Evidence that would convince me: evidence of an increase in genetic diversity at speciation. I thought we were talking about the evolutionary process as a whole, and how it could not increase variation over time? Speciation is just one step in the process.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
Well, maybe you'll get the point and maybe you won't. It isn't a simple additive process. The subtractions that lead to speciation lay waste to all the additions you can come up with. That's the idea anyway. Prove that there's an increase in genetic diversity AT speciation. Simply claiming that mutations are going to prevent the reduction I'm talking about doesn't cut it.
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Taq Member Posts: 10085 Joined: Member Rating: 5.1 |
It isn't a simple additive process. The subtractions that lead to speciation lay waste to all the additions you can come up with. That's completely wrong. A speciation event does not re-establish the genome of a distant ancestor, and it does not force the two new species to have the same mutations. If a mutation occurs in chimps it does not occur in humans just because it occurs in chimps. Furthermore, a mutation that is selected for in chimps may or may not be selected for in humans. The genomes of humans and chimps will continue to diverge over time just as evolution predicts. No future speciation event will cause the chimp or human genomes to become identical to the genome of their common ancestor. Those differences are there to stay. There is no way to reverse them.
Prove that there's an increase in genetic diversity AT speciation. Why should I prove something that I have never claimed? I fully agree that natural selection reduces the number of alleles, including speciation events. However, evolution is not just natural selection and speciation. There is a third mechanism: mutation. Over time these mutations are additive. There is nothing to stop it. Or perhaps you can tell us the mechanism that will rid you of the 100 to 200 mutations that you carry? How does evolution prevent you from passing on these 100-200 mutations to your offspring, and how does it stop an additional 100-200 mutations from occuring in your children? What is stopping this process in any human out there?
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Taq Member Posts: 10085 Joined: Member Rating: 5.1
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A challenge for Faith:
Please explain why it hasn't stopped raining in human history given the limited amount of water that the atmosphere can hold. Also remember that evaporation of surface water is irrelevant to this argument.
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nwr Member Posts: 6412 From: Geneva, Illinois Joined: Member Rating: 4.5 |
Faith writes:
You are not going to find much evidence of that. Generally speaking, the increase in genetic diversity precedes the speciation, and is part of what makes speciation possible. If you are looking for the increase in diversity to happen at the time of a speciation event, then you are looking in the wrong place.Evidence that would convince me: evidence of an increase in genetic diversity AT speciation. Increase in genetic diversity is mainly a gradual process that is always going on. Speciation occurs as speciation events that depend on contingencies in environment that alter the selection forces. Evolution, itself, includes both processes that increase diversity and speciation events.
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PaulK Member Posts: 17828 Joined: Member Rating: 2.3 |
quote: Simply claiming that the reductions of diversity involved in speciation - to the extent there are any - MUST outweigh the additions from mutations doesn't cut it either. You need the numbers. Which is exactly the problem your last argument ran into. And no, we don't need to show that there is an increase of diversity at speciation. Because speciation events don't happen that frequently. If it happens that a new species should happen to have a slightly reduced genetic diversity compared to the parent population it doesn't matter, so long as diversity recovers in a reasonable period. Again, the evidence doesn't show that there is any serious problem with a loss of variation. Your favourite example, the domestic dog, shows plenty of variety. So do pigeons, an example used by Darwin. So, do you have a GOOD reason for discounting mutations ? Because you haven't come up with one in this thread, even though it is the major issue from the last thread.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
When I said that an increase in genetic diversity at speciation would convince me I'm wrong
I was answering the simple question, What would convince me I'm wrong? That would.
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subbie Member (Idle past 1283 days) Posts: 3509 Joined: |
In other words, you'd be convinced of the truth of the ToE if we show you something that is the exact opposite of what the ToE predicts.
Curiouser and curiouser. Ridicule is the only weapon which can be used against unintelligible propositions. Ideas must be distinct before reason can act upon them; and no man ever had a distinct idea of the trinity. It is the mere Abracadabra of the mountebanks calling themselves the priests of Jesus. -- Thomas Jefferson For we know that our patchwork heritage is a strength, not a weakness. We are a nation of Christians and Muslims, Jews and Hindus -- and non-believers. -- Barack Obama We see monsters where science shows us windmills. -- Phat
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CosmicChimp Member Posts: 311 From: Muenchen Bayern Deutschland Joined: |
Prove that there's an increase in genetic diversity AT speciation. But is it not already sufficient to show that diversity can increase, under any circumstance? Furthermore, speciation is a net increase in diversity. Daughter populations taken as a whole, show more diversity than parent populations. Take for instance how the tree of life has diverged. Edited by CosmicChimp, : example added
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
But is it not already sufficient to show that diversity can increase, under any circumstance? It depends. I'll have to ponder this more. First I have to be sure it's an increase in GENETIC diversity, since increase in diversity of traits wouldn't prove anything, and I have to know for certain that the cause is mutation and not some untrackable source of increased gene flow with other populations, or that sort of thing. Beyond that, I have been thinking that even if there are mutations the selective processes will cut them down too, and I need to follow this through before I can answer yes to to your question. But if there is an increase in diversity that doesn't interfere with speciation -- or vice versa -- that would be the clincher for me. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1473 days) Posts: 35298 From: Nevada, USA Joined: |
Furthermore, speciation is a net increase in diversity. Daughter populations taken as a whole, show more diversity than parent populations. Take for instance how the tree of life has diverged. Aha, but you see, here you are talking about the PHENOTYPE, and that I fully recognize increases in diversity. My argument is that when this occurs, the GENETIC diversity decreases correspondingly. (Overall the NUMBER of traits also decreases -- with respect to the former population -- since of course the traits express the alleles, but the appearance of new traits increases.) Edited by Faith, : No reason given. Edited by Faith, : No reason given. Edited by Faith, : No reason given. Edited by Faith, : No reason given. Edited by Faith, : one annoying typo or other error after another Edited by Faith, : No reason given.
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