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Re: [Killietalk] etz
Tim Addis wrote:
Also, would members care to comment on a lack of colour & a reduced
fertility rate being a sign of inbreeding.
How would you pick up on a first sign of inbreeding? Runts, bent backs,
colour reduction, infertility etc.
Despite all the wonderful old wive's tales to the contrary, none of the
above are particularly associated with inbreeding. They *are* closely
associated with very poor selection of breeding stock and other poor
husbandry, but the only possibly negative inbreeding effect is, as Karen
has said, an increase in undesired recessive traits showing up, sooner.
All modern animal husbandry is based on the understanding that
inbreeding (particularly linebreeding) is a sound way to improve a line.
Undesired recessives just get culled from the program, if they show up.
In actual fact, the ability to cull those inferior specimens usually
allows a gradual reduction until they never appear. Because of the way
killies live, most of our original stock comes from such highly inbred,
small populations, that negative-survival recessives have long since
been filtered out, anyway. Only rare mutations can impact them.
I have long suspected that reduced fertility is usually due to the
inability to accurately identify females in many species that readily
hybridize. As the hybrids reproduce, they can gradually become less
fertile. The more they are outcrossed to sound stock, the longer it
takes, but eventually the incompatible genes seems to take fertility on
down. Inbreeding may accelerate that problem, as it seems to take
several generations for fertility to drop below survival levels. That
is, the heterozygosity seems to need a certain threshold before it
really wrecks the strain. Inbreeding just gets one there quicker. [Just
my uneducated guessing, BTW. As a geneticist, I'm a pretty decent
Electrical Engineer. :-)]
Wright Huntley -- 760 872-3995 -- Rt. 001 Box K36, Bishop CA 93514
Mencken's maxim—every election is a sort
of advanced auction of stolen goods.
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