Re: Is there any reason for the evolution to be one way

On Mar 27, 7:01 am, "Perplexed in Peoria" <jimmene...@xxxxxxxxxxxxx>
wrote:
"Shaktyai" <Fabrice.All...@xxxxxxxxx> wrote in messagenews:eu7l0b$1rlj$1@xxxxxxxxxxxxxxxxxxxxxx
Random walk with p=q=0.5 have a zero mean deviation: ie no evolution.
That goes for a model where a mutation of a gene is modeled in a 1D
space. One step on the right or one step for each mutation from state
A to B, from B to C, etc...
Such a model can not reproduce the experimental facts: evolution =
there is a non zero mean deviation = there is a drift in the random
walk.

Yes, such a model can reproduce the experimental facts. Evolution happens
without a mutation bias, due to selection. Evolution can also happen with
neither a mutation nor a selection bias, in which case it is called drift.
Less well known and less important than either of these is evolution due
to a mutation bias. If you want to know about this, I have suggested that
you Google on
mutation pressure G+C
But you need to know that this has nothing to do with why most evolution
takes place.

I have in mind the 1D model (and I may be wrong there !), so the
only solution is to assume that in general: p(A->B) is different from
p(B->A).
To justify this I was thinking about the thermodynamics of a mutation.
In my point of view, the two probability can be equal if E(A)=E(B).
If the free energy of the initial and final state are different then
the system will always spontaneously evolve toward the lower energy
state and the two probability should be different. Of course there is
always the possibity to bridge the energy gap with either a chemical
catalyst, a photoabsortion, or an electronic colisionnal excitation
(electron beam).
I might be all wrong but is there a systematic study of the energy
required for a mutation to spontaneously happen ?

There is a lot of talk about Hamiltonian of Darwin's systems.

Not among biologists, there isn't.

To write
down a satisfactory theory, one must have a density probability whose
integral is always one. In kinetics, this very fundamental point is
induced by the hamiltonian structure that induces Liouville's theorem.

There is nothing corresponding to Lioville's theorem in biology. Biology
does not involve any useful conservation laws. The basic units in biology
*reproduce*. That doesn't happen in chemistry or physics.

In information theory, the probility space is constant and well
defined. But in biology it is far from obvious.

You need to learn something about biology before you try to apply your
physicist's intuitions to the subject. You will no doubt learn that
biology is far more difficult and almost as sophisticated mathematically.
Since you will probably want a mathematically oriented treatment of
evolution, I would suggest that you start your education with Sean Rice's
book "Evolutionary Theory: Mathematical and Conceptual Foundations".
Also, read the chapters on mutation in the Alberts textbook on Molecular
Biology.

Thank you for your time and comments. We may disagree on a few points
but I appreciate any open minded exchange.
Concerning the Liouville operator I am afraid that you might be wrong
there. There are already a couple of Hamiltonian candidates on the
market and from there it is a matter of 5 mn to construct the
Liouville operator. I understand that kinetic theory might look and
sound awfull to a non math oriented mind but there is non doubt in my
opinion that in the very near future a lot of results from kinetic
physics are going to be applied to biology. It is not to prove the
biologists are worth nothing without a physicist supervising them. No,
it is because the physical properties of the DNA molecule are todays
under our microscope. It behaves weirdly, sometimes superconductor,
sometimes not.
There are plenty of conservation laws in biology. Some are obvious
( To talk crudely, biological systems are just a bunch of molecules
that obey the same laws than any other molecules), some are less
evident and are peculiar to the biological systems.
Concerning my studies, I did start with biology and then switched to
mathematical physics. After applying a lot of the tools learned in
finance, in traffic theory, epidiemology, I have become more
interested in the math beyond what you biologists call a random
complex complicated weird system.


.

Relevant Pages

  • Re: Is there any reason for the evolution to be one way
    ... That goes for a model where a mutation of a gene is modeled in a 1D ... Such a model can not reproduce the experimental facts: evolution = ... If the free energy of the initial and final state are different then ... There is nothing corresponding to Lioville's theorem in biology. ...
    (sci.bio.evolution)
  • Re: Evolution a hard sell for many students
    ... broad ideas of evolution theory in Biology 101 class last month at Ohio ... Paul said the lectures are not going to change ... National polls show students are divided on evolution. ... So evolution is about gene recombination, a low level of mutation all ...
    (talk.origins)
  • Re: Added information with mutations
    ... that do have extra hind legs. ... they've generated new mutation that has created some new information ... It's not a useful concept in biology. ... makes sense except in the light of evolution, ...
    (talk.origins)
  • Re: Is there any reason for the evolution to be one way
    ... That goes for a model where a mutation of a gene is modeled in a 1D ... Such a model can not reproduce the experimental facts: evolution = ... If the free energy of the initial and final state are different then ... There is nothing corresponding to Lioville's theorem in biology. ...
    (sci.bio.evolution)
  • Re: Added information with mutations
    ... that do have extra hind legs. ... they've generated new mutation that has created some new information ... biology professor mean by "information"? ... makes sense except in the light of evolution, ...
    (talk.origins)