Re: Directional evolution

DK wrote:
Tim Tyler <seemysig@xxxxxxxxxxxxxx> wrote:

Gould's model resembled the expansion of a gas, next to a wall.

However, common sense suggests the model of a gas expanding next to a
wall - into a *vacuum*. It seems that this model would be better on
the grounds that species may well expand semi-randomly into vacant
adjacent niches - but that one thing that is certain is that the
niches are /initially/ all *empty*.

The niches need not be empty to begin with. Increased complexity =
new and more gene combinations => New niches *and* new chances
to compete for the existing niches. Between the two, some fitness
compromise is always settled upon.

I mean that the niches are /initially/ all empty -
because before the origin of life there were no
creatures at all.

Modeling the medium as a vacuum represents the assumption
that the chances of successfully occupying an adjacent niche
are greater if the niche is currently unoccupied - so
that there is no contest over the niche between the
current occupant and the invader.

This seems plausible to me - or at least it is much
/more/ plausible than Gould's assumption of a random
walk was.
--
__________
|im |yler http://timtyler.org/ tim@xxxxxxxxxxx Remove lock to reply.

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Relevant Pages

  • Re: Directional evolution
    ... common sense suggests the model of a gas expanding next to a ... The niches need not be empty to begin with. ... Modeling the medium as a vacuum represents the assumption ...
    (sci.bio.evolution)
  • Re: Directional evolution
    ... common sense suggests the model of a gas expanding next to a ... The niches need not be empty to begin with. ... Modeling the medium as a vacuum represents the assumption ... Complexity *happens* by random walks. ...
    (sci.bio.evolution)
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