>From:    Edward Lipinski <[log in to unmask]>
>Subject: Nobody Know the Trouble I See; Nobody Know But Jesus.
>When the vast majority of ferrets being propagated as sexual truncates
>(desexed) come to that time and place in the evolutionary fork in the road,
>they simply will go down the fork that leads to extinction.  They will have
>not adapted to change, or if they have, they will not be able to pass on
>that germ DNA particle plasm to any offspring, simply because they are
>incapable of passing their seed to the fertile farm ground of evolution.
>The process of domestication comes to an abrupt halt with your pet-store
>bought ferret.
 
If evolution were occuring in the domestic ferret, it would not occur in
the individual, it only occurs in the species as a whole.  Individual
animals (in this case, ferrets) do not "adapt" in an evolutionary sense,
that would be a Lamarkian idea.  Analogy: giraffes did not get long necks
by stretching to reach leaves, they got long necks because individuals that
survived to reproduce offspring carried the genes for longer necks.  In the
case of the domestic ferret, ferrets are chosen to reproduce not by natural
selection, but by human breeders.  Since our ferrets do not exist in the
wild and survive only because we breed them, they are already domesticated
and evolution is not occurring.  Instead, we make choices about which kind
of ferrets will have offspring, much the same way as we have been making
choices about which dogs, cats, horses, cows, etc. have offspring.  Ferrets
will not become extinct as long as we continue to breed them - afterall,
the cow hasn't become extinct.
 
Furthermore, DNA (deoxyribonucleic acid) is not "germ DNA particle plasm."
From Blood and Studdert (1996) Bailliere's Comprehensive Veterinary
Dictionary, p.264, "DNA molecules are linear polymers of small molecules
called nucleotides, each of which consists of one molecule of the
five-carbon sugar deoxyribose bonded to a phosphate ... single strand of
DNA is made by linking the nucleotides together ... in cells, the DNA is
double-stranded ... the two strands form a double helix." A single linear
thread of DNA (double helix), in turn, may be tightly coiled in the form of
a chromosome, which is located in the nucleus of each nucleated cell of the
ferret (or other animal).  Humans have 46 chromosomes, dog have 78 ... by
the way, does anyone know how many the ferret has?
 
>One should learn from the keepers of dog and cats.  There are 135 different
>"races" of dogs and some "37" different "races" of cats.  The dog and
>cat breeders are constantly breeding their critters for specific
>characteristics, health, stamina, resourcefullness, and longevity.  What
>are the vast majority of ferret keepers doing?  Nothing.
 
If we learn anything from the keepers of dogs and cats, it probably should
be to keep the number of ferret breeds to a minimum.  Quite the contrary to
health and stamina, most dog and cat breeds have inherited genetic diseases
or are predisposed to other diseases, thus comes the phrase "hybrid vigor"
(ie. mutts tend to be healthier).  The doberman pinscher has Von Willabrand's
disease (an inherited bleeding disorder), German shepherds have hip
dysplasia, pugs are brachycephalic (short wide heads with the same length
respiratory system = difficult breathing).  A sure way to keep your local
veterinarian in business is to start making ferret breeds (ie. a group of
animals within a species with unusual characteristics).
 
To make "breeds" of ferrets, we would probably have to start by in-breeding
on a certain genetic line.  We would select a hob or jill with a
characteristic that we liked, breed him/her and then take any kits of that
breeding that had the desired characteristics and breed them back with the
orginal hob or jill that had the characteristic that we liked.  This would
continue until we developed the desired characteristics.  Unfortunately, in
addition to the characteristic we liked (say fennec fox ears), those inbred
ferrets would likely inherit some unwanted traits (say increased incidence
of cardiomyopathy) because the chosen traits and the unwanted trait might
lie close to each other on the same chromosome and be inherited together.
In addition, the desired traits (say fennec fox ears) might have some
undesireable aspects (say increased incidence of ear infections).  All in
all, it likely means more work for the vets to keep the ferrets healthy.
 
Evolution, natural selection, genetics, and breeding are more complicated
than what I have written.  If you are really interested in this stuff, Bob
Church usually does a better job teaching it in his FML posts than a lot of
professors that I have had over the years.  I highly recommend rereading
his past posts.
 
******************************
Sean D. Sawyer V'00
University of Pennsylvania
School of Veterinary Medicine
 
[log in to unmask]
******************************
 
[Moderator's note: Well, since you asked, Bob Church says ferrets have
40 chromosomes (FML 1707), though he also mentions the number might vary
(FML 1390).
 
As for cows becoming extinct, actually, there is concern that some breeds
of cows and other domesticated animals might indeed become extinct.  One
good article about this appeared in Science News (Vol 152 Num 14, Oct 4,
1997.  http://www.sciencenews.org/sn_arc97/10_4_97/bob1.htm to read it).
This should not be taken to mean that I agree with Mr. Lipinski.  It just
means I have a big mouth and a good memory.  BIG]
[Posted in FML issue 2394]