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 Posted: Thu Mar 20, 2008 5:19 pm Post subject: Role of yunk-DNA |
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A lot of evolution can be described as continuous, gradual change of
pre-existing structures. The change from a dinosaur front limb to a
bird wing can be described as gradual changes in arm proportions,
muscle strengths etc.
It is also true that the factors that control these properties can
also be expressed as variables: the timing of gene-expression (earlier-
later), the quantity of a certain gene-product (more-less),
concentration-gradients that control phenotypic traits (steeper-
shallower).
A trait (and gene-expression) can only vary in a continuous, gradual
way, if something in the genome varies in a continuous, gradual way.
For DNA, being digital code, this is not obvious. Digital code is
sensitive to change. A change in the coding region of a gene will
likely result in a non-functional gene-product. There is no clear
correlation between genetic change and phenotype change.
However, what can vary in a continuous, gradual way? DNA-length.
That>s the role of yunk-DNA. It allows for the controlled and measured
introduction of variation in a population, making continuous, gradual
evolutionary change possible. |
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Tim Tyler
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| Posted: Sat Mar 22, 2008 5:19 am Post subject: Re: Role of yunk-DNA |
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br.hessels@planet.nl wrote:
[quote]A trait (and gene-expression) can only vary in a continuous, gradual
way, if something in the genome varies in a continuous, gradual way.
For DNA, being digital code, this is not obvious. Digital code is
sensitive to change. A change in the coding region of a gene will
likely result in a non-functional gene-product. There is no clear
correlation between genetic change and phenotype change.
[/quote]
Measure the magnitude of such changes and a correlation would
be pretty clear.
[quote]However, what can vary in a continuous, gradual way? DNA-length.
[/quote]
Strictly speaking, that>s just as digital as other aspects of DNA.
[quote]That>s the role of yunk-DNA. It allows for the controlled
and measured introduction of variation in a population,
making continuous, gradual evolutionary change possible.
[/quote]
Um, that>s not right :-(
--
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Guest
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| Posted: Sat Mar 22, 2008 5:57 pm Post subject: Re: Role of yunk-DNA |
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[quote]For DNA, being digital code, this is not obvious. Digital code is
sensitive to change. A change in the coding region of a gene will
likely result in a non-functional gene-product. There is no clear
correlation between genetic change and phenotype change.
Measure the magnitude of such changes and a correlation would
be pretty clear.
[/quote]
I>m sure there>s a correlation between the amount of genetic change
and phenotypic change, but it>s not obvious that the genetic code can
change in that way.
There is something inherently discrete in digital code. Take language
for example. A change of a letter in a word will likely either a)
destroy the meaning completely or b) change the meaning entirely.
There is no clear relation in the sense that a slight amount of change
in spelling changes the meaning of the word slightly. (Of course it is
true that an addition of a letter changes the the number of letters in
a correlated way.)
The same applies to genetic code.
[quote]However, what can vary in a continuous, gradual way? DNA-length.
Strictly speaking, that>s just as digital as other aspects of DNA.
[/quote]
It seems to me that the genetic code, the particular order of
nucleotides, that is, let>s say, implemented onto the DNA molecule is
digital, whereas the length of the DNA molecule is, well, just the
length of a molecule, analog.
[quote] > That>s the role of yunk-DNA. It allows for the controlled
> and measured introduction of variation in a population,
> making continuous, gradual evolutionary change possible.
Um, that>s not right :-(
[/quote]
Well, it should be right, I predict it to be right... :-)
(Also: yunk-DNA should be spelled junk-DNA) |
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Graham Jones
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| Posted: Mon Mar 24, 2008 5:57 pm Post subject: Re: Role of yunk-DNA |
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<br.hessels@planet.nl> wrote in message
news:fs3haa$2peq$1@darwin.ediacara.org...
[quote]Take language
for example. A change of a letter in a word will likely either a)
destroy the meaning completely or b) change the meaning entirely.
[...]
(Also: yunk-DNA should be spelled junk-DNA)
[/quote]
!
Graham |
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