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Author Topic:   Iconic Peppered Moth - gene mutation found
Taq
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Message 61 of 76 (785633)
06-08-2016 12:13 PM
Reply to: Message 60 by Faith
06-06-2016 11:26 PM


I kept thinking of the pocket mice through this whole discussion too. Same situation.
Indeed, it is. In both situations we have a long history of strong negative selection against a dominant allele. This means that any mutations leading to dark coloration would be almost immediately eliminated from the population in past environments. Therefore, the mutations had to occur after the negative selective pressure was removed.
Do you agree?
Edited by Taq, : No reason given.

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 Message 60 by Faith, posted 06-06-2016 11:26 PM Faith has replied

Replies to this message:
 Message 62 by jar, posted 06-08-2016 12:22 PM Taq has replied
 Message 67 by Faith, posted 06-08-2016 6:35 PM Taq has replied

  
jar
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Posts: 34058
From: Texas!!
Joined: 04-20-2004
Member Rating: 4.9


Message 62 of 76 (785638)
06-08-2016 12:22 PM
Reply to: Message 61 by Taq
06-08-2016 12:13 PM


This means that any mutations leading to dark coloration would be almost immediately eliminated from the population in past environments. Therefore, the mutations had to occur after the negative selective pressure was removed.
I think we need to repeat WHY that must be true.
If such a mutation happened before the soot(lava) filled world the moth (mouse) would get eaten and so the trait, even though a dominate one, would not get passed on to future generations. The gene that would get passed to future generations would be the recessive one.
In Faith's asserted world though both genes are in every critter since she is asserting that the potential for everything is built in in some original "kind" formula.
The problem is that ALL of the very detailed evidence shows that is simply not the case. All the genetic evidence from long before Adam would have existed shows that things were pretty much like they are today.
She simply does not believe the evidence.

Anyone so limited that they can only spell a word one way is severely handicapped!

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Taq
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Posts: 10158
Joined: 03-06-2009
Member Rating: 4.4


Message 63 of 76 (785639)
06-08-2016 12:27 PM
Reply to: Message 62 by jar
06-08-2016 12:22 PM


jar writes:
If such a mutation happened before the soot(lava) filled world the moth (mouse) would get eaten and so the trait, even though a dominate one, would not get passed on to future generations. The gene that would get passed to future generations would be the recessive one.
This is especially true of a dominant allele. Every individual carrying a single allele for dark coloration would experience negative selection. For a recessive gene, only individuals carrying two copies of the allele will experience negative selection. Recessive alleles will not be eliminated as quickly from a population, but given strong enough selective pressures they will be removed. As examples, there are many lethal recessive genetic diseases that are still circulating in the human population (e.g. Tay-Sachs disease).
Edited by Taq, : No reason given.

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Dr Adequate
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Posts: 16113
Joined: 07-20-2006


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Message 64 of 76 (785649)
06-08-2016 2:02 PM
Reply to: Message 59 by Taq
06-06-2016 6:00 PM


It is interesting to note from the paper that different populations of black mice have different genetic bases for their color.

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Taq
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Posts: 10158
Joined: 03-06-2009
Member Rating: 4.4


(1)
Message 65 of 76 (785658)
06-08-2016 2:49 PM
Reply to: Message 64 by Dr Adequate
06-08-2016 2:02 PM


It is interesting to note from the paper that different populations of black mice have different genetic bases for their color.
Just as there is more than one way to skin a cat, there is more than one way to produce dark coloration. There are several different proteins and genes involved in the timing and extent of melanin production. Any one of those genes is a target for mutations that can change fur and skin coloration.
The fact that you have islands of black lava each with their population of mice with unique alleles is an indication that they evolved independently of one another and did not originate from a common mutation found in an ancestral population.

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Dr Adequate
Member (Idle past 368 days)
Posts: 16113
Joined: 07-20-2006


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Message 66 of 76 (785661)
06-08-2016 3:12 PM
Reply to: Message 65 by Taq
06-08-2016 2:49 PM


Yes, that's what makes it interesting.

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Faith 
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Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 67 of 76 (785673)
06-08-2016 6:35 PM
Reply to: Message 61 by Taq
06-08-2016 12:13 PM


I kept thinking of the pocket mice through this whole discussion too. Same situation.
Indeed, it is. In both situations we have a long history of strong negative selection against a dominant allele. This means that any mutations leading to dark coloration would be almost immediately eliminated from the population in past environments. Therefore, the mutations had to occur after the negative selective pressure was removed.
Do you agree?
I don't think this situation proves either the usual idea about mutations or the built-in allleles idea. Mutations are not supposed to come along on cue to meet a need, so there is something different going on here that has not been explained yet.
The built-in -- or pre-existing allele (or mutation) -- idea would mean that, yes, every time a black version popped up, as it would quite regularly, being dominant, MOST of them would be picked off but a few would survive so that allele would continue in the population -- even under severe negative selection until it was positively selected.
That seems unlikely but so does the other scenario.
Edited by Faith, : No reason given.

This message is a reply to:
 Message 61 by Taq, posted 06-08-2016 12:13 PM Taq has replied

Replies to this message:
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Dr Adequate
Member (Idle past 368 days)
Posts: 16113
Joined: 07-20-2006


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Message 68 of 76 (785676)
06-08-2016 8:24 PM
Reply to: Message 67 by Faith
06-08-2016 6:35 PM


I don't think this situation proves either the usual idea about mutations or the built-in allleles idea. Mutations are not supposed to come along on cue to meet a need ...
And they didn't. Mutations arise randomly. We have explained this to you.
The built-in -- or pre-existing allele (or mutation) -- idea would mean that, yes, every time a black version popped up, as it would quite regularly, being dominant, MOST of them would be picked off but a few would survive so that allele would continue in the population -- even under severe negative selection until it was positively selected.
How would a black version "pop up" if it was "pre-existing"?

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 Message 67 by Faith, posted 06-08-2016 6:35 PM Faith has replied

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Faith 
Suspended Member (Idle past 1528 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 69 of 76 (785714)
06-09-2016 12:07 PM
Reply to: Message 68 by Dr Adequate
06-08-2016 8:24 PM


I don't think this situation proves either the usual idea about mutations or the built-in allleles idea. Mutations are not supposed to come along on cue to meet a need ...
And they didn't. Mutations arise randomly. We have explained this to you.
You are invited to do the probability calculations, but my rough guess is that to get a specific adaptive trait like a color that matches the background, you'd need something in the thousands or maybe millions of tries before it would show up.
How would a black version "pop up" if it was "pre-existing"?
I did explain though perhaps not clearly enough. It would be heterozygous in a very small number of individuals and would get expressed (pop up) in the population in every generation, and MOST of them would be eaten but a few would manage to survive and the same gene would show up in the next generation in extremely small numbers.
As I said, it's improbable. And so is the mutation explanation improbable.

This message is a reply to:
 Message 68 by Dr Adequate, posted 06-08-2016 8:24 PM Dr Adequate has replied

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14174dm
Member (Idle past 1192 days)
Posts: 161
From: Cincinnati OH
Joined: 10-12-2015


Message 70 of 76 (785720)
06-09-2016 1:03 PM
Reply to: Message 69 by Faith
06-09-2016 12:07 PM


It would be heterozygous in a very small number of individuals and would get expressed (pop up) in the population in every generation
I don't think that would work in your idea of super gene. Since black is dominate, all the mice be black until the black gene was mutated to junk dna. So in order for there to be light mice to survive on the desert sand, they would have already lost the black gene.
Then there would not have been a black gene for the lava mice to use.

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JonF
Member (Idle past 251 days)
Posts: 6174
Joined: 06-23-2003


(3)
Message 71 of 76 (785729)
06-09-2016 1:57 PM
Reply to: Message 69 by Faith
06-09-2016 12:07 PM


You are invited to do the probability calculations, but my rough guess is that to get a specific adaptive trait like a color that matches the background, you'd need something in the thousands or maybe millions of tries before it would show up.
Probably a reasonable guess.
13.5 million humans born each year, each with something on the order of 100 mutations.
16.5 million dogs born each year in the US alone.
Variation, Selection and Time: A Recipe for Biodiversity:
quote:
Many varieties of mice are used as model organisms in laboratory experiments all over the world. As a result mice have been extensively studied, including their mutation rates. Mice have 5 billion DNA bases in their genome and mutation at any one base occurs in about 2 out of every billion bases. There are about 1000 bases in an average gene that can be mutated. Multiply 1000 bases per gene times 2 mutations per billion bases and we get that mutation occurs in a specific gene in about 500,000 individuals. Mice breeding labs have found several mice mutants involving fur color traced a gene called MC1R. There are 10 sites within this gene that if mutated cause the mice’s coat color to be black even if they carry only one copy of the gene (all mice have 2 copies of every gene just as human have 2 copies of every gene — 1 from your mother and 1 from your father).
Table 3. Mice Mutation Rates
s
Mutation Rate2 per 1,000,000,000 bases
Number of sites in MC1R that can be mutated to make a mouse black10
Number of copies of MC1R gene 2
On your answer sheet, calculate the number of mutant mice having a black causing mutation in the MC1R gene that you would expect in 1 billion mice. What are the odds of just one mouse having a black causing mutation in the MC1R gene? [Answer question 7]
Now let’s look at mice population size and birth rates — factors that play a role in the determining how long it takes for one mutation to arise. Pocket mice live in population sizes that range from 10,000 to 100,000 individuals. These mice also have a high reproductive rate — on average 5 babies are born to every female per year. Calculate the number of babies born in a population of 10,000 individuals each year. [Answer question 8]
Multiply answer 8 by answer 7 [Answer question 9]
Your calculations should reveal that in 1,000,000 years, a black-causing mutation will occur independently 1000 times. Every 1000 years you could say that our population of 10,000 pocket mice {i.e. a small population - JonF}hit the black mutation jackpot! How often would a larger population, say 100,000 individuals hit the jackpot? Show your calculations on your answer sheet. [Answer question 10]


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Dr Adequate
Member (Idle past 368 days)
Posts: 16113
Joined: 07-20-2006


(3)
Message 72 of 76 (785730)
06-09-2016 2:54 PM
Reply to: Message 69 by Faith
06-09-2016 12:07 PM


You are invited to do the probability calculations, but my rough guess is that to get a specific adaptive trait like a color that matches the background, you'd need something in the thousands or maybe millions of tries before it would show up.
I'd think closer to millions than thousands. Now, since there are lots of moths, and since there's a new generation every year, it's not going to take at all long for a one-in-a-million mutation to crop up, is it?
I did explain though perhaps not clearly enough. It would be heterozygous in a very small number of individuals and would get expressed (pop up) in the population in every generation, and MOST of them would be eaten but a few would manage to survive and the same gene would show up in the next generation in extremely small numbers.
As I said, it's improbable.
Indeed, since it requires thousands of years of this gene going unnoticed by entomologists and natural selection alike. Meanwhile the probability of it arising by mutation is so large as to amount to a crushing inevitability.

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Taq
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Posts: 10158
Joined: 03-06-2009
Member Rating: 4.4


Message 73 of 76 (785937)
06-13-2016 3:22 PM
Reply to: Message 67 by Faith
06-08-2016 6:35 PM


I don't think this situation proves either the usual idea about mutations or the built-in allleles idea. Mutations are not supposed to come along on cue to meet a need, so there is something different going on here that has not been explained yet.
First, the idea of a pre-existing dark allele is thoroughly disproven. The allele would have been removed from the population in the absence of these lava fields due to negative selection. Therefore, it had to come about through mutation after the lava fields were produced by relatively recent volcanic eruptions.
Second, you haven't shown that it showed up on cue. There could have been hundreds of thousands of years between the volcanic eruptions and the occurrence of the mutation. You also haven't shown the rate at which the mutation appears in the absence of the black lava fields. What we do know is that the reason for the difference in fur color is mutations.

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 Message 67 by Faith, posted 06-08-2016 6:35 PM Faith has not replied

  
Taq
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Posts: 10158
Joined: 03-06-2009
Member Rating: 4.4


Message 74 of 76 (785939)
06-13-2016 3:25 PM
Reply to: Message 69 by Faith
06-09-2016 12:07 PM


You are invited to do the probability calculations, but my rough guess is that to get a specific adaptive trait like a color that matches the background, you'd need something in the thousands or maybe millions of tries before it would show up.
As shown above, that is easily done in a mouse population. Even using your number of a million births in order to get one black mouse, that is easily done with even a small population of 10,000 mice. That is just 100 generations for a species with a 3 month generation time. That would be about once every 30 years, by my calculations.

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 Message 69 by Faith, posted 06-09-2016 12:07 PM Faith has not replied

  
jar
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Posts: 34058
From: Texas!!
Joined: 04-20-2004
Member Rating: 4.9


Message 75 of 76 (785962)
06-13-2016 8:34 PM
Reply to: Message 69 by Faith
06-09-2016 12:07 PM


Faith writes:
I did explain though perhaps not clearly enough. It would be heterozygous in a very small number of individuals and would get expressed (pop up) in the population in every generation, and MOST of them would be eaten but a few would manage to survive and the same gene would show up in the next generation in extremely small numbers.
As I said, it's improbable. And so is the mutation explanation improbable.
There is one thing that you need to learn about probabilities Faith. The probability that some specific thing will happen after it is known that it DID happen is 100%.
In the case of the peppered moth being discussed in this thread the probability is 100%.
In the case of the mice, the probability that each of the DIFFERENT mutations happened is still 100%.
The probability that humans descended from Chimpanzees is 100%
Improbable things happen.
When dealing with large populations and large numbers of events over long periods of time the probability of almost anything happening always approaches 100%

Anyone so limited that they can only spell a word one way is severely handicapped!

This message is a reply to:
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