> Here is a quote from Suzuki et al briefly describing genetic drift:

> ""If a population is finite in size (as all populations are) and if a
> given pair of parents have only a small number of offspring, then even
> in the absence of all selective forces, the frequency of a gene will not
> be exactly reproduced in the next generation because of sampling error.

Note how Suzuki et al jumps to the conclusion that the 
observation (a gene will not be exactly reproduced in the 
next generation) dictates the conclusion that the cause of 
this observation is, "sampling error," which is nonsensical 
in light of the fact that sampling error is not causal.

Note also that the supposition that, "sampling error," is 
or can be causal is nonsensical.  To sample involves 
measurment of a population (Sampling of a population).  What 
this breaks down to is that measurement causes the change 
that the measurements measure.  Pure nonsense.

> If in a population of 1000 individuals the frequency of "a" is 0.5 in
> one generation, then it may by chance be 0.493 or 0.0505 in the next
> generation because of the chance production of a few more or less
> progeny of each genotype.

Note how Suzuki et al jumps to the conclusion that the 
observation (a gene will not be exactly reproduced in 
the next generation) dictates the conclusion that the 
cause of this observation is, "chance production."  

Note also that the supposition that, "chance production," 
is or can be causal is nonsensical.  

>  In the second generation, there is another
> sampling error based on the new gene frequency, so the frequency of
"a"
> may go from 0.0505 to 0.501 or back to 0.498. This process of random
> fluctuation continues generation after generation, with no force pushing
> the frequency back to its initial state because the population has no
> "genetic memory" of its state many generations ago. Each generation is
> an independent event. The final result of this random change in allele
> frequency is that the population eventually drifts to p=1 or p=0. After
> this point, no further change is possible; the population has become
> homozygous. A different population, isolated from the first, also
> undergoes this random genetic drift, but it may become homozygous for
> allele "A", whereas the first population has become homozygous for
> allele "a". As time goes on, isolated populations diverge from each
> other, each losing heterozygosity. The variation originally present
> within populations now appears as variation between populations."
> (Suzuki, D.T., Griffiths, A.J.F., Miller, J.H. and Lewontin, R.C. in An
> Introduction to Genetic Analysis 4th ed. W.H. Freeman 1989 p.704)

> Larry Moran puts it simply, "One aspect of genetic drift is the random
> nature of transmitting alleles from one generation to the next given
> that only a fraction of all possible zygotes become mature adults.

Note how Larry never bothers to point out that randomness 
is already explicitly included in NS and so, the supposition 
that genetic drift is distinctive because it involves 
randomness is a false distinction.

>  The
> easiest case to visualize is the one which involves binomial sampling
> error. If a pair of diploid sexually reproducing parents (such as
> humans) have only a small number of offspring then not all of the
> parent's alleles will be passed on to their progeny due to chance
> assortment of chromosomes at meiosis.

Note how Larry jumps to the conclusion that the observation 
(a gene will not be exactly reproduced in the next generation) 
dictates the conclusion that the cause of this observation is, 
"chance,"  which is plainly nonsensical in light of the fact 
that chance is not causal.

>  In a large population this will
> not have much effect in each generation because the random nature of the
> process will tend to average out. But in a small population the effect
> could be rapid and significant." Larry Moran, Random Genetic Drift
> Copyright 1993-2000
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