I think nature will normalize the built if it can. Just my non-science-based opinion.
You cross a Pug with a normal nosed dog and the pups have functional noses.
Ash always explains this very well. I hope she sees the thread.If a roached back and straight back are bred together, how does the genetics effect the progeny. Is it fifty fifty chance that a pup from that combination will be of either type? Or is it that one of these types is more dominant?
Because they didn't give nature the chance to normalize them by breeding dysfunctional traits to each other and let these win in the show ring.Hmmm...that doesn't explain why English Bulldogs have to have c-sections because of human interference in physical structure.
I tested a show line litter yesterday. The mother has a very moderate structure and top line. The sire more of the common type. Some of the pups have his top line and some were like mom. One of the puppies was very nice at testing, but has her dad's top line. I kept telling the breeder, love her temperament, hate her top line. Anyhow, breeding a more moderate dog can give one some more moderate pups.
Well said. Physical appearance is usually not controlled as a single gene trait in higher order species like mammals. It is a complex trait with many genes on different loci being expressed or silenced depending on the expression of genetics and environment in that particular dog.I have no experience with this specific genetic example, but the likelihood that the "roach back" is one gene is slim to none scientifically. The classic Mendel's pea plants example is very basic genetics and deals with a trait in which phenotype is based on one gene and thus genotype can be inferred from mere observation. Most physical traits are not anywhere near this basic. Many genes are at play and how they combine is very hard to determine and predict.
Most of the times, when you breed extremes in phenotype (extreme angulation to a flat top line for example), you get a mishmash of structure with no obvious uniformity or type in the litter.
I see this with poorly thought out working/show crosses - people toss a WL and SL together and expect genetics to cherry pick the best working characteristics of the WL to meld with the best structural features of the showline to somehow produce a litter of "the best of both worlds"
But in reality, structure and temperament is usually all over the place with no clear predictable phenotype and no consistency.
So I imagine your pretend scenario is the same TEZPUR1976
Without knowing the dogs in question, their bloodlines, how these lines express themselves, how they mix with other lines, how strongly they pass on structure or some particular trait....your guess is as good as mine as to what two unknowns with varying extremes in structure will produce
I will tell you the formula for consistent, predictable, and reliable results - find someone that knows what they are doing, is honest about their results, and will point you to the right dog for you based on your criteria.