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An Ice Breakthrough!

We had an in-depth discussion on the Ice factor in the yahoo group pigeongenitics101, and I asked Gene Hochlan the following question to sum it all up for me. Gene is one of the top genetics experts alive today. 
Q: Ice is not an actual gene but the result of selective breeding?

A: All of the evidence we have from various fanciers over the years definitely points in that direction. I prefer using the term "directional breeding" and Douglas McClary has pretty much proven that with his good work in producing "powdered" which, in my opinion, is a form of primitive Ice. The "powdered" Show Racing Homers are close to Ice but are not quite there yet. Paul Gibson's summary statement; "manipulated genetic drift" also pleases me. I believe our group discussion (in pigeongenetics101) phased out the old belief that Ice is a distinct mutated gene and that is why no one has ever gotten the expected progeny testing results. Am not entirely sure if someone should get credit for this breakthrough but I believe that we have an original achievement where our pigeongenetics101 group site is concerned. You may do whatever suits you with the above information. It is important and should be shared with the pigeon world.

More comments from Gene: This phenotype does not respond to normal testing procedures. When Ice is mated to wild type the result is an overall, half-tone copy and if you pair up the crosses they will produce more of the same with a slight variation of blue shades.  Once in a great while a decent colored Ice is produced.  Fanciers have found it necessary, when introducing Ice into a different breed, to back cross to Ice in order to make any real progress.
Paul Gibson referenced "manipulated genetic drift" when we concluded our discussion on this subject. In nature all "wild type" phenotypes are the result of genetic drift due to the sum of all environmental conditions, hazards and mutations.  The end results that we see in wildlife have taken thousands and sometimes millions of years.  In confinement we can manipulate this process and put it on "fast track". The Ice coloration that we see in Damascenes and Ice Pigeons is very similar to a new, man made "wild type".  Had it not been for Douglas McClary's work in producing "powdered" through directional breeding, always selecting for the lightest blues, we would still be groping in the dark concerning Ice.  If I remember correctly it took him 50 years to make his accomplishment and that is true dedication.

Most of us have a picture in mind as to what the original Rock Pigeon (Columba livia) should look like but that image may be erroneous.  The variation of the blue ground color varies from very light to extremely

dark.  The best illustration I have ever come across depicting the Rock Pigeons from around the globe is in Derek Goodwin's book - Pigeons and doves of the world.  It is unfortunate that this color plate cannot be purchased separately.  The darkest blue Rock Pigeon comes from tropical West Africa and the lightest one from the Dakla Oasis.  All of these birds are perfectly fertile when interbred.
Suppose we mate the two color extremes together.  I doubt seriously that one blue version would be dominant
to the other and our outcome would be an intermediate shade of blue.  This depicts my reasoning where the
Ice phenotype is concerned.  Someone in the distant past did not have an Ice blue pigeon appear in the nest
as a mutation but rather this phenotype was created incrementally; over many years.  If we mate Ice to "normal"
blue it will completely disappear in three to four generations.
In summary then the blue ground color of pigeons can be altered through directional breeding without actually changing the basic gene or genes responsible for it.

Q: So that means Ice is the phenotype of a domestic breed of Blue Bar without any additional modifiers present?

A: According to my deductive reasoning that would be correct.  A man-made wild type