Re: Coefficients...
[Re: Todd E. Gaster ]
#5887 - 06/10/2003 06:42 AM |
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Laura,
yes that is what I was asking.. Does a homozygous dog, tend to throw more of his traits than a heterozygous dog that has the same "Percentage of Blood"? I can follow the math, just trying to get more background info.
thanks
-Matt |
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Re: Coefficients...
[Re: Todd E. Gaster ]
#5888 - 06/10/2003 06:44 AM |
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also, I am not necessarily speaking about GSDs, just asking a general genetics question.
-Matt |
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Re: Coefficients...
[Re: Todd E. Gaster ]
#5889 - 06/10/2003 10:35 AM |
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Originally posted by MattMoore:
Does a homozygous dog, tend to throw more of his traits than a heterozygous dog that has the same "Percentage of Blood"? I can follow the math, just trying to get more background info. My understanding is that, yes, this is more *generally* true. Not always though.
The interesting thing about this is that if one looks at the Coefficient of Inbreeding of the top GSD working studs over the past few decades, one *generally* finds low COIs (low levels of homozyosity). So I can only assume that the close linebreeding that leads to higher levels of homozygosity must also *generally* cause sufficient problems (like poor health, or weak nerves, or whatever) that it's the exception, rather than the norm... at least in the working lines.
Close linebreeding is popular in the showlines of many breeds, because it does tend to produce a consistent "physical type". Given that working dog breeders use close linebreeding much less frequently, this begs the question what aspects of "mental type" (working abilities, temperament) or health the showline breeders give up simply due to their infatuation with close linebreeding?
Laura
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Re: Coefficients...
[Re: Todd E. Gaster ]
#5890 - 06/10/2003 10:59 AM |
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From everything I've read, behavior genetics isn't very predictable. The temperament/behavior traits that make working dogs successful are considered to have low heritability, so linebreeding wouldn't improve your product much. On the other hand, physical characteristics needed in the show dog have higher heritability, thus linebreeding is more common.
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Re: Coefficients...
[Re: Todd E. Gaster ]
#5891 - 06/10/2003 11:22 AM |
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One can see qiute a bit of linebreeding in the Malinois...
that is interesting that there is very little in the GSD world, perhaps this is due to the difference in gene pool availability
-Matt |
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Re: Coefficients...
[Re: Todd E. Gaster ]
#5892 - 06/10/2003 11:22 AM |
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Originally posted by Lee Baragona - Sch3FH2:
From everything I've read, behavior genetics isn't very predictable. The temperament/behavior traits that make working dogs successful are considered to have low heritability, so linebreeding wouldn't improve your product much. On the other hand, physical characteristics needed in the show dog have higher heritability, thus linebreeding is more common. It make sense that complex polygentic traits that determine the working abilities in a multipurpose working dog like the GSD would tend to have low heritability.... just due to the genetic complexity (many genes involved). In contrast, physical traits like coat color can involve much simpler genetics, and higher heritability.
What sources can you recommend that document heritability of behavioral traits?
I found one source, a report by The Seeing Eye (guide dog organization). They have been studying the results of their breeding programs with Labs and GSDs. They report that "trainability" to be guide dogs has a heritability of 0.15-0.20. This is quite low (1.00 would be perfectly predictable heritability), even lower than what's been found for hip dysplasia which is also a polygenetic trait.
Laura
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Re: Coefficients...
[Re: Todd E. Gaster ]
#5893 - 06/10/2003 11:29 AM |
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Originally posted by MattMoore:
One can see qiute a bit of linebreeding in the Malinois...
that is interesting that there is very little in the GSD world, perhaps this is due to the difference in gene pool availability I asked a working malinois breeder about that. The answer was surprising... you can't believe the malinois pedigrees. The working mali genepool is split between FCI and non-FCI registered populations. There are (according to this breeder) a lot of non-FCI dogs getting into the FCI genepool, and breeders just falsify the pedigrees... making it look like there is more linebreeding going on then there really is. This breeder feels that DNA testing of the FCI malinois will be the death of that genepool as a working breed.
Let's set that aside and assume that indeed there is more linebreeding being done today in the working mali genepool than in the working GSD genepool. I wonder if this has anything to do with the massive amount of inbreeding that took place to "set type" in the GSD breed in the early years of the breed? Possibly the accumulated inbreeding baggage in the working GSD genepool makes it less tolerant of additional inbreeding/linebreeding today.
Laura
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Re: Coefficients...
[Re: Todd E. Gaster ]
#5894 - 06/10/2003 11:32 AM |
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All three of Willis' books on genetics talk about it, even specifically the traits to be successful in Schutzhund. Scott and Fuller discuss it, and Fuller published a separate book "Behavior Genetics" (I tried it; it was over my head!).
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Re: Coefficients...
[Re: Todd E. Gaster ]
#5895 - 06/10/2003 11:45 AM |
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Re: Coefficients...
[Re: Todd E. Gaster ]
#5896 - 06/10/2003 12:12 PM |
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See you all got way over my head. I believe the litter I was talking about is a good match, phiysically and behaviorally. I was just trying to figure out if it was paperwise. As the typical linebreeding wasn't there. I knew it wasn't a complete outcross either. So using all the tools of the trade how do you put it together paper wise to see exactly what is coming from whom? I know you can never get exact dealing with genetics. But in a nutshell.
Ps. I still can't get WinCanis to work, and Yvonne couldn't help. She said ask the person who told me it could be done.
<img src="/ubbthreads/images/graemlins/confused.gif" alt="" /> <img src="/ubbthreads/images/graemlins/frown.gif" alt="" />
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