| I don't think you will find exact, proven answers to the kind of questions you pose.
Breeding is an art, not an exact science. One example that dog breeders have to contend with is the case of chromosomal inheritance. I'm sure you'll understand this from your studies of human genetics. Dogs have 39 chromosome pairs; humans have 23. During reduction division, the chromosome pairs separate, one of each pair going into one or the other side of the nucleus. The nucleus then divides,leaving each half with 39 chromosomes, one of each kind.
The key to this is that it is pure chance how the chromosomes line up before cell division.
A method to illustrate this:
Take two sets of poker chips or paper -- for example, red and white poker chips. Number each set 1 through 39. Mix them together in a bowl and then draw them out one at a time. Arrange them into two piles, 1 through 39.
When you have finished, you will have two piles numbering 39 each. But they will not be all the same color in either pile. (Well, they could, but it is exrtremely unlikely.)
You can let red represent the sire and white the dam, and the two piles will represent the two halves of the germ cell in reduction division.
This can be enlarged further by setting up another group with blue and yellow chips representing your bitch (be sure to discard one pile, which would represent the polar body that is discarded in reduction division of the female). Now add the male chromosomes, giving you 78 chromosomes, or 39 pairs.
Now set up two equal piles. Each pile represents just one of the possible chromosome combinations your puppies might inherit. How many chips represent each of the grandparents? If you keep selecting different combinations, you will see that it is possible that one of the grandparents might not be represented at all.
Now put all the chips back and do it again. No matter what you got the first time, it will be different the second time. Even if the colors are the same, you would find that the different chromosome numbers are different.
An exception to this is when a mutation occurs.  |