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Discussion Starter #1
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?
 

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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.
 

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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.

Hmmm...that doesn't explain why English Bulldogs have to have c-sections because of human interference in physical structure.
 

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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?
Ash always explains this very well. I hope she sees the thread.
 

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Good question!Now I'll have do some research and see I can find out!
 

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Hmmm...that doesn't explain why English Bulldogs have to have c-sections because of human interference in physical structure.
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.
Breeders have a hard time retaining these sad shaped faces (that's what one of those breeders told me, except the word "sad").
 

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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.
 

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Discussion Starter #9
"...The sire more of the common type."

Do u mean the sire has sloped back as in a showline dog?

Ur observation is in line with my guess.

If we relate with Mendel's pea plant expt, say R =roached back
S=Straight back

Suppose the sire is SS and dam RR, then a pup will be of the type SR (am i correct)?

The phenotype of SR is likely to be moderately roached ?

I think the case

"... The mother has a very moderate structure and top line. The sire more of the common type..."

refers to SR bred with RR. The a pup has 3/4 chance of being SR (moderately roached) and 1/4 chance of RR Roached back type.

This perhaps explains the observation

"...Some of the pups have his top line and some were like mom..."


Of course I am assuming in SR , some amount (even if very mild) of roach will be present in the phenotype.



Best

SD






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.
 

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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.
 

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Discussion Starter #11
TRUE. What I suggested is a oversimplification. But thats how generally mathematical models evolve, in stages. 1st an oversimplified model based on crude assumptions and then model is refined with more realistic but complicated assumptions.

Ok. Let us ask a similar question.

Has any body observed a litter born to a combination of dogs, one with extreme angulation, roach back and the other almost a straight back, where all the pups have moderate angulation or are almost straight back?

This should give some insight.

Thanks for the inputs so far

SD
 

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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.
 

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When I have more time, I will try to use my own dogs and pups to illustrate what I mean through pictures. I have dogs out of several different kennels - yet all of them have unifying traits that easily identify them as one of mine and show consistency with my idea of "type"

Genetics aren't a guessing game if you do it right. That is why we pour over pedigrees and bloodlines and progeny and results.....why are certain breeders successful in consistently producing strong dogs? It's not luck!

They predict correctly and their genetic gambles pay off because they have knowledge, experience, and probability on their side.
 

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Sorry for my spam of replies, but to answer your initial question:

No, a roached back is NOT the dominant top line or structure. Nobody breeds for this trait, it is not desired, and it certainly would not win in the show ring.
A roached back is a structural fault where there is a point on the top line that is higher than the height at the withers. SV show venues select against roached dogs, and there is no preference for this type of structure.
 

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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.
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.

You cannot use simple pea genetics to speak to what will be produced from two dogs with extremes in structure being bred together without knowing more specifics about the breeding in question.

It's like asking what a baby from two parents of different ethnicities will end up looking like... Well we don't know unless we know more - if you see what I mean
 

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Discussion Starter #17
mixing lines to capture "the best of both worlds" is NOT wise. Compromise two different goals never yield good result in general (i have seen this far too many times in my 38 years).

An analogy in finance is the ULIP (unique linked insurance plans) which fooled a lot of people in India during 2004 to 2011.

It was introduced with same idea to capture the best of stock market investment and insurance cover.

People ended up pay very high premium for very ordinary amount of risk cover, and also earned very poor returns after 5 years. A lot of their money went into something the companies called portfolio management.

Same is the case of hybrid funds which tried to lure the risk averse investors into stock market by promising "capital protection" and "high return" through active risk mangement. Finally they ended up achieving none.

In my examples, i am specific about one particular physical triat, topline sloping. Thanks for the clarification on the term "roach back".

So my query is slightly re framed as what happens in the top line of litter where the sire has excess slope and the dam is flat back (or the reverse)?

From ur post i guess the extent topline slope in that litter will vary between the two extremes without any predictable pattern?

Pls correct if i am wrong

best SD







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.
 

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You still don't understand my point.

If I asked you, what will a child from two parents of completely different ethnicities look like, what would you tell me?
You would ask me for more information so you could make an educated guess because my question is far too broad.

Your question is the same. Too broad and poorly phrased - nobody can answer a question like you pose without knowing more about the two dogs in question.

Yes you are asking about a single physical trait - but topline is not a SINGLE GENE trait so how would anyone know the outcome of your hypothetical without know more about the breeding dogs?

My post didn't say it will vary - my post says your question is too general and too basically phrased to yield any true answer so your guess is as good as mine.

Topline is not a single trait on top of all that.
Topline is defined and modulated by the dog's length to height ratio, height at the withers, front shoulder angulation, rear angulation, tail set, croup length and lay, underline, spine, hip angulation, and more.

See why it is not so simple?

To make a prediction, we need to know the breeding dogs in question and more importantly how these genetics traditionally expressed themselves in progeny.
 
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