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Originally Posted by Cares4Dogs   awesome thread!!! I love talkin genetics, but for some reason I cannot retain it and ALWAYS have to break out the biology books for reference  and take great notes. This thread is a keeper in my favorites.
Thanks a bunch for posting on this topic. |
I've heard that breeding Yorkies is part science, part art, and part luck. The science part alone is daunting for me, but some of it is starting to gel.
Below is something I copied and pasted from the link I posted. I find it interesting because I had never seen the importance of the dam emphasized so.
In all mammals the females are "X" "X" and males are "X" "Y" which means that only females carry the genetic code particular to the part of the gene string that is missing in all males. Horse Breeders refer to it the "X Factor" and have demonstrated that the gene responsible for the large heart so many great racing stallions have can be traced back thru their motherlines to a single mare that lived more than 100 years ago. If a stallion has an oversized heart - like Secretariat - this particular mare will show up in his motherlines over and over again. The mares themselves don't have the large heart but they carry the gene for it on their “X” chromosome. Like wise the stallions do not throw the large heart themselves.
And so it is with German Shorthairs. The bitches are far more important than the studs in carrying particular genes forward. Understand that this is true even if the genes most sought were originally found in a pre-potent male. The key for any successful Breeder is to isolate those females that carried his traits and breed off of them. It has been our experience that many important traits are indeed sex linked and carried by the dames from generation to generation.
Successful Breeders realize they are fighting "the drag of the breed," which is the tendency for all animals to breed back toward mediocrity. If it didn't work this way super species and super races would have developed long ago in every animal on earth. For instance in human beings it is impossible to breed parents with high IQs together to produce higher IQs. Even when two genius have children the average IQ of their children will be half way between normal and the average of their IQs.
It's not about Yorkies specifically, but it does make me think of things in a different way. I had read before of Huddersfield Ben being the product of several generations of mother/son breedings. The info I posted above helps put into perspective, for me, why it was mother/son rather than father/daughter breedings.