theories of dominance

Joe Felsenstein joe at GENETICS.WASHINGTON.EDU
Wed Mar 17 20:05:22 EST 1993


Daniel Smith wrote --

>    I am writing a paper on the theories of dominance from a molecular view.  I
> have already examined the papers of Fischer, Wright, Ohh, Rendel, Kacser, Wadd
> ington (canalizing selection and dominance) and one or two others, but I need
> more help.  Can anyone suggest an author, a paper or a book for me to turn to?
> Also, Fisher(1928) and Wright(1929) are, to say the least, esoteric and
> difficult to follow.  I am willing to offer you my first born child (or, at
> the very least, one of his or her limbs) if you could point me in the
> direction of a source that explain the theories of these two brilliant Brits.

Please spare the child.  Fisher (not Fischer) was a Brit but Wright was
American.  Fisher pointed out that mutations which are maintained
in a population by mutation balanced by selection against the mutation
would be present mostly in heterozygotes. If there were modifier genes
available which made the effect of the heterozygote more like that of the
wild-type, these would be favored by natural selection.  He felt that
dominance of wild type alleles was in general an evolved property.

Wright disagreed, pointing out that as these heterozygotes were themselves
rare there would be very weak selection on these modifiers (if they existed)
and that there were good physiological reasons to expect that
mutants inactivating a gene would in general start out as much more recessive
than domiannt.  Much the same view was taken by H. J. Muller ("Evidence
of the precision of genetics adaptation," The Harvey Lectures, Series XVIII,
1950) and J. B. S. Haldane (Journal of Genetics, 1939), whose papers would be
worth attention here.   My understanding of Henrik Kacser's theory is that
it is similar to Muller and Haldane's with some more enzyme kinetics.

-----
Joe Felsenstein, Dept. of Genetics, Univ. of Washington, Seattle, WA 98195
 Internet:         joe at genetics.washington.edu     (IP No. 128.95.12.41)
 Bitnet/EARN:      felsenst at uwavm



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