Re: Pressure"?

On Thu, 14 Sep 2006 21:36:03 -0400, "Dana Tweedy"
<reddfrogg@xxxxxxxxxxx> wrote:


"Dick" <remdickhm@xxxxxxxxxxxxx> wrote in message
news:27pjg25obn54o70fv8ccl5d3fh96hq7e91@xxxxxxxxxx
snip

Because there is always the "crowd" forming as new members of the
population are being added. When food gets scarce, it's as if the
"room" is being reduced in size. Crowding gets worse, and competition
for the 'space' inside the room gets more intense.

DJT

I doubt an individual organism thinks about "crowding." It goes about
each day trying to find nutrition. If it fails it dies, if it is too
weak, it becomes food, etc.

My understanding is the survivors breed thus maintain their gene pool.

Because the English language does not have a singular pronoun that means his
or her, people often use the plural pronoun "their" to refer to individuals.
I just want to make sure you aren't doing so in the above sentence, as the
"gene pool" is the population, not the individual. An individual does not
have a "gene pool" as such. If you mean the population of surviors, then I
apologize.

"Survivors" is plural. However, a population can be one survivor,
right? In this day and age we have "endangered species" with small
populations. How does your concern about my use of gene pool explain
the use of "pressure" and its implied application to a gene pool?


Then this one individual has a mutation that gives it an advantage and
it breeds this new DNA line. If the mutation has a neutral impact for
survival, its chances remain the same as pre-mutation. Most mutations
result in weaker forms, thus their mutation gene pool is lost.

No, most mutations do not "result in weaker forms". Most mutations are
neutral. Some mutations are harmful, and those normally get culled out of
the population. Beneficial mutations can become fixed in the population.


I would think the individual with the mutated gene has no awareness of
the change to it nor the changes in it environment. Things just are
as experienced.

That's correct, the individual with the mutation is normally not aware of
it.


"Pressure" strikes me as a Lamarkian environmental impact which
induces mutation.

Pressure does not induce mutation. It simply affects which mutations will
be either benefical or harmful.


I would have no question if Lamark was the source.
It just seems strange to use "Pressure" in the context of NS.

Again, pressure does not cause more mutations, it simply intensifies the
effect of a mutation on the gene pool.

How does this "pressure" "intensify" the mutation's effect?

Isn't the environment neutral? It seems to me, neither the
environment nor the mutated organism do any more than interact.
Pressure is measured by resistance to movement. In a drought how does
the organism resist?

I gather the word, pressure, has become important in the lexicon for
NS discussions. I am surprised there is not a history how this
"selection" came to be. Pressure would make good sense if we were
discussing Lamarkian mutations.

dick



DJT


.

Relevant Pages

  • Re: Pressure"?
    ... Pressure suggests directed forces. ... accidental mutations either fit their environment ... Mutations can be nutral, ...
    (talk.origins)
  • Re: Pressure"?
    ... Pressure suggests directed forces. ... accidental mutations either fit their environment ... Mutations can be nutral, ...
    (talk.origins)
  • Re: Pressure"?
    ... Pressure suggests directed forces. ... accidental mutations either fit their environment ... Mutations can be nutral, ... Because it fits, when taken in context. ...
    (talk.origins)
  • Re: Pressure"?
    ... Pressure suggests directed forces. ... I understand your criticism, there are neutral mutations. ... It's perhaps not a very good metaphor, ... organism has no "awareness" of changes in the environment. ...
    (talk.origins)
  • Re: Pressure"?
    ... Pressure suggests directed forces. ... I understand your criticism, there are neutral mutations. ... It's perhaps not a very good metaphor, ... organism has no "awareness" of changes in the environment. ...
    (talk.origins)