dkomo  wrote:

> John Wilkins wrote:
> > 
> > William L Hunt  wrote:
> > 
> > > On Fri, 20 Feb 2004 17:00:33 +0000 (UTC), dkomo

> > > wrote:
> > >
> > > >William L Hunt wrote:
> > > >>
> > > >> On Wed, 18 Feb 2004 22:57:56 +0000 (UTC), dkomo

> > > >> wrote:
> > > >>
> > > >> >>Tim Tyler wrote:
> > > >> > dkomo  wrote or quoted:
> > > >>
> > > >> >> Web pages of unknown origin are not
necessarily good resources.
> > > >> >>
> > > >> >
> > > >> >This was a set of lecture notes from a course
at University College
> > > >> >London:
> > > >> >
> > > >> >http://www.ucl.ac.uk/
> > > >> >
> > > >> >The course was "C339 Sex, Genes and
Evolution 2004":
> > > >> >
> > > >> >http://www.ucl.ac.uk/~ucbhkof/stalkie/c339
> > > >> >
> > > >>  I'll just point out that Tim is being a little
harsh because the
> > > >> website makes clear they "assume" equal
investment cost for male and
> > > >> female offspring. From that "assumption"
they derive/use a primary sex
> > > >> ratio of 1:1.
> > > >
> > > >Please be advised that I don't by any means consider the argument
> > > >about what Fisher actually said to be concluded.  I
think both you and
> > > >Tim Tyler are wrong.  Fisher never used terminology like
"equal
> > > >investment cost."  His original theory of the sex
ratio is as I stated
> > > >in my previous post where I quoted from the lecture notes.
> > > >
> > > >I've carried this as far as I can for the moment because
I don't have
> > > >time to run off to the local university library and
reference Fisher's
> > > >_Genetical Theory of Natural Selection_, where he
presented his sex
> > > >ratio theory.  I'm instead relying on secondary sources
which I have
> > > >on hand which are interpretations of Fisher's theory.
> > > >
> > > >You can simply provide the relevant quote from Fisher's
book to prove
> > > >me wrong, and I'll accept that -- but only that.
> > > >
> > >  I'll quote from the website you provided (lecture notes):
> > >
> > > "Fisher: optimal sex ratio reflects the cost
> > > of producing each sex.
> > > If males are twice as costly to produce as
> > > females, then males are only worth
> > > producing if they have twice the
> > > reproductive success of females. This will
> > > occur when there are twice as many
> > > females as males in the population. That
> > > is, the optimal sex ratio is 1:2.
> > > In order to determine the optimal sex ratio,
> > > the number of individuals of each sex must
> > > be weighted by the cost of producing this
> > > sex."
> > >
> > >  Why would you think this is not also from Fisher when they are saying
> > > it is? Or why would you accept what they say is from Fisher in one
> > > section but not what they say is from Fisher in another?
> > >  I would also have to reference Fisher's book to be sure what he
> > > "exactly" said.
> > >  William L Hunt
> > >
> > > ...
> > > [snip]
> > > ...
> > > >   --dkomo{at}cris.com
> > > >
> > 
> > Page 158ff in the 1958 edition (but no apparent resetting from the 1930
> > edition); excuse typos:
> > 
> > In organisms of all kinds the young are launched upon their careers
> > endowed with a certain amount of biological capital derived from their
> > parents. This varies enormously in amount in different species, but, all
> > in all, there has been, before the offspring is able to lead an
> > independent existence, a certain expenditure of nutriment in addition,
> > almost universally, to some expenditure of time or activity, which the
> > parents are induced by their instincts to make for the advantage of
> > their young. Let us consider the reproductive value of these
> > off-[159]spring at the moment when this parental expenditure on their
> > behalf has ceased. If we consider the aggregate of an entire generation
> > of such offspring it is clear that the total reproductive value of the
> > males in this group is exactly equal to the total value of all the
> > females, because each sex must supply half the ancestry of all the
> > generations of the species. From this it follows that the sex ratio will
> > adjust itself, under the influence of Natural Selection, that the total
> > parental expenditure incurred in respect of children of each sex, shall
> > be equal; for if this were not so and the total expenditure incurred in
> > producing males, for instance, were less than the total expenditure
> > incurred in producing females, then since the total reproductive value
> > of the males is equal to that of the females, it would follow that those
> > parents, the innate tendencies of which caused them to produce males in
> > excess, would, for the same expenditure, produce a greater amount of
> > reproductive value; and in consequence would be the progenitors of a
> > larger fraction of future generations than would parent having a
> > congenital bias towards the production of females....
> > 
> > The sex-ratio at the end of the period of expenditure thus depends upon
> > the differential mortailty during that period, and if there are [160]
> > such differences, upon which the differential demands which the young of
> > such species make during their period of dependency; it will not be
> > infulenced by differential mortality during a self-supporting period;
> > the relative numbers of the sexes attaining maturity may thus be
> > influenced without compensation, by differential mortality during the
> > period intervening between the period of dependence and the attainment
> > of maturity. Any great differential mortality in this period will,
> > however, tend to be checked by Natural Selection, owing to the fact that
> > total reproductive value of either sex, being, during this period, equal
> > to the other, whichever is the scarcer, will be the more valuable, and
> > consequently a more intense selection will be exerted in favour of all
> > modifications tending towards its preservation. The numbers attaining
> > sexual maturity may thus become unequal if sexual differentiation in
> > form or habits is thus for other reasons advantageous, but any great and
> > persistent inequality between the sexes at amturity should be found to
> > be accompanied by sexual differentiation, having a very decided binomic
> > value. 
> > 
> > God, there was a man who knew how to use a comma...
> > --
> 
> And semicolons.  And long paragraphs.  
> 
> I ran across a number of comments on the web about _Genetical Theory
> of Natural Selection_.  Many biologists consider Fisher's book to be
> second in importance only to _Origin of Species_ for the theory of
> evolution.  Fisher, however, ranks far down the list from Darwin for
> prose style, IMHO.
> 
It was noted in the obits for William Hamilton that he had hoped at the
end of his life to get a first in Fisher's GToNS. The book is deep -
really deep, despite the eugenics of the latter half. The reason why I
typed all that out by hand was to read it in detail (a process that
works well for me, as I'm a lousy typist and have to proofread
carefully). It was worth it. I now have about six independent lines of
thought from those two paragraphs...

-- 
John Wilkins
john_SPAM{at}wilkins.id.au   http://wilkins.id.au
"Men mark it when they hit, but do not mark it when they miss" 
                                               - Francis Bacon
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