The recent discussions on gene pool size have had some statements made that
can obscure the real situation.  A distinction has to be made between
potential and reality.  For example, a statement was made that a large
research oriented breeder may have more breeding animals but a smaller gene
pool.  That could happen, but it is not realistic.  We have a large lab
mouse breeder in our state and they produce very homogenous strains of mice
(a requisite for validity).  However, the demand for any particular strain
is small, so they have hundreds, if not thousands, of specialized strains.
Thus, the facility has access to a large gene pool even though a given line
may have little variation.  While animal research is not a favored topic
here, the needs of these people are very varied and specific, so any
research breeder that only had a small number of strains would go out of
business for lack of demand.  This discussion is obviously directed at one
particular ferret breeder and this breeder has more color lines and other
characteristics than any other source I'm aware of.  So lets not damn an
operation because of what could be, even if that isn't realistic.
 
Another potential that was mentioned is that a smaller breeder with a wide
source of ferrets can have a larger variability in genes.  Again, this can
be true to start, but limited breeding can eliminate these and lose the wide
potential quickly.  If the animals don't produce enough offspring, all their
genetic potential may not be passed on.  A small breeder may start with a
good gene pool, but the low number of offspring may limit the gene variation
in each succeeding generation.  This is how isolated populations get
homogenous.  We've heard about deer mouse strains that can't interbreed.
How did that happen?
 
Genetics is a probability game, and the odds for expression are not uniform.
For any probability prediction, it's accuracy is limited to predicting the
outcome of a large number of trials, not individual events.  So for a range
genes to be expressed in succeeding generations, large numbers of offspring
are required, or constant infusion of outside genetic material.  If a group
has 20 genes for some characteristic, but only 8 offspring, how many get
transmitted?  How do you think ethnic characteristic in humans came about?
Even with the genetic potential, the low birth/survival rate winnowed down
the potential even in large geographic areas.  Suddenly, a group has
distinctive hair color, eye color, cheekbones, height, etc.  even though the
whole human race has many more possible types.
 
When you throw in the recessive, dominant and incomplete dominance of
genetic traits, the picture gets more muddy.  A recessive trait can be
passed along and express itself generations later after having
"disappeared." I've seen a number of people express interest in horse
racing.  On a Nova program a few years back, they contrasted the lack of
change in time records in horse racing versus human track events.  They
stated that all current race horses in the US can be traced back to 5 horses
imported in colonial times (I accept their statement as true, I don't care
enough to check it out and consider them a credible source).  The lack of
genetic variation has produced a fairly standard horse and their speeds have
not improved much over this century.  Track events have shown a tremendous
change, even in the years before training method improvement became
emphasized and a factor.  One explanation is the huge variation in human
genetic makeup creates different capabilities.
 
The point underlying all this is that hypothetical constructs can be made to
explain all sorts of outcomes.  Testing them against results has to be done
before they can be accepted.  A small breeder could have a larger gene pool
than a large breeder if certain constraints are accepted.  However, these
constraints are not the reality.  Many small breeders concentrate on
producing specific traits.  Their ads state so.  I don't see all that much
emphasis on producing variation, but creating certain packages of desirable
traits and then locking them in.  Just because small breeders introduce new
stock, they do so often with a specific purpose.  They choose what to
introduce.  This is not the random breeding that produces wide genetic
variation.
 
   ( )--(a)
   (@=@=) \     Till next time.......Rudy the ferlosopher
   O__)  \ \___
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      /\ * )  \
[Posted in FML issue 1534]