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Author Topic:   Does Neo-Darwinian evolution require change ?
slevesque
Member (Idle past 2813 days)
Posts: 1456
Joined: 05-14-2009


Message 46 of 114 (601079)
01-18-2011 4:26 PM
Reply to: Message 36 by AZPaul3
01-18-2011 11:27 AM


Re: The Dance of the Population Curves
See previous post since I think it adresses some of what you are saying here.

Stasis is not a period of no change either in the individual attributes' population curves or the central optimal line, but change slow enough to appear somewhat stable over geologic time frames.

But can change be slowed down that much ? The only force that can potentially work against change and for stasis is selection, and it seems not only that the higher the mutation rate, the higher selection pressures most be to maintain stasis, but also that as JonF said, that in the multi-dimensional landscape of things there are many potential for change, which would turn selection around to work against stasis.


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Dr Jack
Member (Idle past 278 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 47 of 114 (601081)
01-18-2011 4:35 PM
Reply to: Message 45 by slevesque
01-18-2011 4:17 PM


Microbes, evolution's cavalry
There's a really simple way to test your ideas: have viruses, within your lifetime, failed to demonstrate stasis? Viruses have mindboggling high error rates, and incredibly rapid generation times. If you're right, viruses should be fundamentally changing all around us.

Don't like viruses? How about E. coli? They can rock through a generation every 20 minutes under ideal conditions. If you're right, why haven't they succumb to your weight of mutations?


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slevesque
Member (Idle past 2813 days)
Posts: 1456
Joined: 05-14-2009


Message 48 of 114 (601082)
01-18-2011 4:38 PM
Reply to: Message 38 by PaulK
01-18-2011 12:36 PM


Re: Mutation rates
However, if I understand correctly this measures the whole genome, most of which appears to have no function. If I am correct, a large majority of these mutations will be truly neutral having absolutely no effect whatsoever. Slevesque's argument requires the majority to be detrimental, so he needs to use the far smaller number of mutations within functional regions of DNA (genes, regulatory sequences and the like).

And what % of the genome do you think has a function ? 5% ? 10% ? 30% ?

The truth is we don't really know, but this has been an ever increasing number in the past couple of years. I think most geneticists today would say at least 30%, but the ENCODE project has opened the possibility that the entire genome would be functional, and even that some times both sides of the DNA strand is useful, putting it's functionality at over 100%.


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slevesque
Member (Idle past 2813 days)
Posts: 1456
Joined: 05-14-2009


Message 49 of 114 (601083)
01-18-2011 4:51 PM
Reply to: Message 44 by Dr Jack
01-18-2011 4:16 PM


Re: Population size, and the incredible excess of fecundity
Yes, and some plants produce 100 offsprings each generation. And more offsprings does mean mor leverage for natural selection to work on.

But it also means a whole boatload of new mutations in the population. It means although the workforce of NS is bigger, the work to be done is also bigger. (all other things equal)

This is why the reproduction rate influences the potential for selection, but it is the mutation rate that effects the cost of selection. The higher the rate, the higher the cost, and vice versa

Think about it with a small rate. If 1 in 10 individuals inherits a mutation (o,1mpipg) then the cost is low, and selection can easily pay the bill to eliminate the mutation with any normal reproductive rate above 1,1.


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slevesque
Member (Idle past 2813 days)
Posts: 1456
Joined: 05-14-2009


Message 50 of 114 (601086)
01-18-2011 5:01 PM
Reply to: Message 47 by Dr Jack
01-18-2011 4:35 PM


Re: Microbes, evolution's cavalry
What are the mutation rates ? How much selective pressure can the species support ? etc. These are some of the question that you need to answer if you want to analyse the potential of any given species for stasis.

Turns out E.Coli has both right answers for it to be able to maintain stasis. It's mutations rate is under 1mpipg and it can withstand enormous selective pressures (you can rebuild the entire population even after having decimated it to a few individuals. genetic meltdown is not an option)

quote:
Since the overall mutation rate is lower than the size of the E. coli genome, on average there won’t be any mistakes made when the cell divides into two daughter cells. That is, the DNA will usually be replicated error free.

http://sandwalk.blogspot.com/2007/07/mutation-rates.html


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New Cat's Eye
Inactive Member


Message 51 of 114 (601088)
01-18-2011 5:07 PM
Reply to: Message 46 by slevesque
01-18-2011 4:26 PM


Re: The Dance of the Population Curves
But can change be slowed down that much ?

Perhaps its not as much as you think?

How unchanging do you think stasis is? How much do you think change has to be slowed down to in order to be stasis?


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Taq
Member
Posts: 7934
Joined: 03-06-2009
Member Rating: 3.8


Message 52 of 114 (601090)
01-18-2011 5:13 PM
Reply to: Message 41 by slevesque
01-18-2011 3:43 PM


Of course this is all probabilities talk, since obviously population size goes up and down. But it cannot for too long downwards, because genetic meltdown is never far away.

You have yet to show this. Also, as a population dwindles over a few generations this can reduce the deleterious mutation load far easier than in a growing or stable population. You can have a cycle of booms and busts that negate genetic meltdown.


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Taq
Member
Posts: 7934
Joined: 03-06-2009
Member Rating: 3.8


Message 53 of 114 (601091)
01-18-2011 5:15 PM
Reply to: Message 50 by slevesque
01-18-2011 5:01 PM


Re: Microbes, evolution's cavalry
Turns out E.Coli has both right answers for it to be able to maintain stasis. It's mutations rate is under 1mpipg and it can withstand enormous selective pressures (you can rebuild the entire population even after having decimated it to a few individuals. genetic meltdown is not an option)

You can also reduce a mammalian population from millions to a few thousand and re-establish the species.


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AZPaul3
Member
Posts: 4140
From: Phoenix
Joined: 11-06-2006
Member Rating: 3.5


(1)
Message 54 of 114 (601099)
01-18-2011 5:55 PM
Reply to: Message 46 by slevesque
01-18-2011 4:26 PM


Re: The Dance of the Population Curves
But can change be slowed down that much ?

Doesn't have to be. Remember what Natural Selection actually is.

Yes, in the most egregious cases it kills the individual. But in the majority of instances Natural Selection simply means reduced or enhanced reproductive success.

In the case of the dancing population curves any changes or group of changes that move the apex of the curve away from the optimum (which is set by the present environment) will correct itself by those in the population closer to that optimum having more babies and moving the curve over time back toward that optimum. And this is done for each of the thousands of attributes. It is a self-correcting mechanism.

Remember, also, that this is based upon the fossil record which can only preserve the most gross phenotypic structures. Most mutations in a population affect the soft(er) parts (since there are so many more of them) and the type of gross morphological structure changes you may be thinking of are rare to begin with in stable populations. In the case of PE, which involves sexual species, sexual selection in the base population would tend to preclude the type of "hopeful monster" you may envision from becoming a part of the population.

Major changes by mutation may indeed enter the population and become fixed for a specific attribute. It may even re-mix this idealistic optimum. But the designation of "species" from the fossil record is based on the gross phenotype which, as the evidence shows, can vary little to none at all over geologic timescales. By definition this is stasis.

{abe} And just to be pointed about it... Nothing can ever overwhelm Natural Selection (selection pressures) regardless of perceived cost. It is a nonsensical notion. Any change, rate of change, high or low that has any effect on reproductive success is part of the Natural Selection phenomenon. If the changes enhance reproductive success then these are said to be "selected for" while any that reduce reproductive success are deemed "selected against" regardless of how many there may be or how fast the come.

Edited by AZPaul3, : No reason given.


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PaulK
Member
Posts: 15085
Joined: 01-10-2003
Member Rating: 3.3


Message 55 of 114 (601102)
01-18-2011 6:17 PM
Reply to: Message 48 by slevesque
01-18-2011 4:38 PM


Re: Mutation rates
quote:

And what % of the genome do you think has a function ? 5% ? 10% ? 30% ?

The truth is we don't really know, but this has been an ever increasing number in the past couple of years. I think most geneticists today would say at least 30%, but the ENCODE project has opened the possibility that the entire genome would be functional, and even that some times both sides of the DNA strand is useful, putting it's functionality at over 100%.


It doesn't matter what MY opinion is. The point is that you are assuming 100% (which even ENCODE did not show). And last I heard ENCODE was coming under heavy criticism for misinterpreting the data and badly overestimating the amount of DNA transcribed (not used - just transcribed).

Another study using a more accurate methodology found:


...most of the genome is not appreciably transcribed.

Most “Dark Matter” Transcripts Are Associated With Known Genes


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Percy
Member
Posts: 18498
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.9


Message 56 of 114 (601105)
01-18-2011 6:20 PM
Reply to: Message 43 by slevesque
01-18-2011 3:58 PM


Re: How much does a selection cost?
slevesque writes:

What you are fogetting is that we aren't just bacteria, where each generation is a single cell division.

Ask yourself, how many cell divisions, each with 75 mutations, happens between the time of the first cell division of a newly fertilized ovum, and the time that cell has become a man and himself procreates.

The ~2.5x10-8 value is for the human intergenerational mutation rate, not the rate for the division of individual human cells, here's the reference to the 2000 paper that finds a lower rate:

Estimate of the Mutation Rate per Nucleotide in Humans, M. W. Nachman, S. L. Crowell, Genetics 156, 297-304, 2000

I also expressed my opinion that the value was probably open to revision, and here's the reference that WK just provided to a 2010 paper:

Analysis of Genetic Inheritance in a Family Quartet by Whole-Genome Sequencing, Roach et. al. Science Vol 328 no. 5978 pp. 636-639

Relevant excerpt from the abstract:

Roach et. al. writes:

We also directly estimated a human intergeneration mutation rate of ~1.1 × 10−8 per position per haploid genome.

So we see two estimates from the technical literature that are not too far apart from one another. If you prefer other estimates then you need some references, and in your concluding paragraph about Sanford's figures you say:

I'll try finding the rates he cites...

Good idea. Once we have mutation rate figures we agree on we can plug them in and see what happens.

--Percy

PS - If you click on the "Peek Mode" radio button before cut-n-pasting you'll get 10-8 instead of 10-8 in the text you quote.


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Wounded King
Member (Idle past 2267 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 57 of 114 (601114)
01-18-2011 7:31 PM
Reply to: Message 48 by slevesque
01-18-2011 4:38 PM


Re: Mutation rates
the ENCODE project has opened the possibility that the entire genome would be functional, and even that some times both sides of the DNA strand is useful, putting it's functionality at over 100%.

I know that talking nonsense about the ENCODE data is the latest thing in ID/creationism but can't you at least try to make it sound a bit less insane. Being rarely transcribed does not confer meaningful functionality on a genetic sequence. As deep sequencing technologies improve it is unsurprising that we see an increase both in the signal and the noise of the bioinformatic data sets we have.

To leap from discovering a few transcripts of unannotated genetic regions to assuming that the whole genome is more than 100% functional shows a complete disconnection not just from molecular genetics but from reality itself.

You were wrong when you were spouting this rubbish in March (Message 24) and you haven't got any righter since.

TTFN,

WK

Edited by Wounded King, : No reason given.

Edited by Wounded King, : No reason given.


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Taq
Member
Posts: 7934
Joined: 03-06-2009
Member Rating: 3.8


Message 58 of 114 (601119)
01-18-2011 8:03 PM
Reply to: Message 48 by slevesque
01-18-2011 4:38 PM


Re: Mutation rates
but the ENCODE project has opened the possibility that the entire genome would be functional, and even that some times both sides of the DNA strand is useful, putting it's functionality at over 100%.

Just in case the horse isn't dead . . .

You have made the mistake of conflating functional with transcribed. Even taking the kindest view of the ENCODE results, the best one can say is that nearly all of the genome is transcribed at some point. However, just because an mRNA is produced does not indicate that it has function. Even more, the number of transcripts per cell is so low for most of these mRNA's that function is doubtful. To use an analogy, you are looking for a signal in the static that doesn't exist. Sometimes you just have to admit that it just is random noise.


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Coyote
Member (Idle past 279 days)
Posts: 6117
Joined: 01-12-2008


Message 59 of 114 (601125)
01-18-2011 8:50 PM
Reply to: Message 40 by slevesque
01-18-2011 3:32 PM


Re: Eldredge & Gould -- stasis is stasis because ...
Since I do think the ratio is not so good, and that the high mutation rates should be leading all species towards extinction, and that this fits right in with my YEC position.

YEC. There is the problem.

The empirical evidence overwhelmingly supports an old earth, with life starting some billions of years ago.

That evidence is absolutely incompatible with the idea of this genetic meltdown in a few hundred generations.

Put simply, if the genome hasn't melted down in 3+ billion years, we don't need to worry about it.


Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
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jar
Member
Posts: 30997
From: Texas!!
Joined: 04-20-2004
Member Rating: 4.2


Message 60 of 114 (601127)
01-18-2011 8:53 PM
Reply to: Message 59 by Coyote
01-18-2011 8:50 PM


Re: Eldredge & Gould -- stasis is stasis because ...
There has not even been much change in the Genome of most anything since the time of Adam.


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