Re: Evolution lessons
- From: john@xxxxxxxxxxxxx (John S. Wilkins)
- Date: Mon, 27 Sep 2010 08:51:14 +1000
Burkhard <b.schafer@xxxxxxxx> wrote:
On 26 Sep, 22:50, Ray Martinez <pyramid...@xxxxxxxxx> wrote:
On Sep 26, 1:29 pm, Jack Dominey <jack_domi...@xxxxxxxxx> wrote:
On Sat, 25 Sep 2010 09:21:12 -0700, Boikat wrote:
Nope. Again, you're putting the cart before the horse. The variations
that could lead to speciation (If that is what you are asking about)
occurs all the time within a population. It does not *manifest* itself
(through speciation) unless there is some change in the environment that
allows any particular variable trait to provide a reproductive
advantage, and therefore, increase the odds of that trait being passed
along and spread through following generations. It's a feedback loop.
C'mon, Boikat, you've been reading and posting to t.o. long enough to
avoid the pitfall of treating selection as being preeminent.
Over time a species will change genetically due to drift and other non-
selective reasons (sorry to be handwaving, drift is the only one I can
think of right now). Selection pressure can certainly contribute to
speciation, but it's not required.
NS is preeminent, not drift.
That depends entirely on the population size. In small populations,
drift can overpower NS. In large populations, NS ends to be more
dominant, unless the allele frequency is very low. Suzuki et al (An
Introduction to Genetic Analysis) give a good explanation why this is
the case, as does Hart and Clark's 1998 " Principles of population
genetics". For an update, especially on recent claims to detect
previously overlooked examples of selection with new statistical
methods, see Masatoshi Nei, Yoshiyuki Suzuki, and Masafumi Nozawa The
Neutral Theory of Molecular Evolution in the Genomic Era. Annual
Review of Genomics and Human Genetics
Vol. 11: 265-289 2010
Read Gould 2002 or any other book
published by a Darwinist in the latter half of the 20th century.
Actually, Rayray, if you *do* look at Gould 2002, you will find a number
of discussions on drift, esp 722 where he says
"... sorting can proceed randomly, a process called _drift_. In the
hierarchical model [which SJG promotes], both selection and drift can
occur at all levels, under appropriate conditions."
Looks like Gould was not so selectionist as you think from just reading
chapter titles. You might also read the discussion on p542ff.
It's not enough to *buy* the books, Ray. You also have to *read* them.
John S. Wilkins, Philosophy, Bond University
But al be that he was a philosophre,
Yet hadde he but litel gold in cofre
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