Wright's/Hardman's Coefficient - Page 1

Would like for some one to explain how the Wright's/ Hardman's coefficient works. Are these numbers indicating the amount of genetic DNA found in a particular dogs bloodline's?

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I am searching the forums trying to find an explanation of Wright's/Hardman's Coefficient also.  Can anyone give a reasonably simple explanation of this?

Ron Hudson said: "Are these numbers indicating the amount of genetic DNA found in a particular dogs bloodline's?"

NO, the amount of DNA should be identical for all dogs unless they have a genetic disorder (like downsyndrome in humans that has an extra chromosome 21). What does vary is homozygosity, since all dogs have two copies of each gene, the question is if the copies are the same or not.

For example, using just one gene. (Agouti)

V Bomber vom Wolfsheim 
is Homozygous for a/a Black/Black  (Gene is the Same)
Will pass on the black gene to 100% of progeny

V Bandit vom Wolfsheim 
is Heterozygous for A/a Sable/Black (Gene is Not The Same)
Will pass on the black gene to 50% of progeny and Sable to 50%

Within a population a certain percentage of the DNA varies from individual to individual. These differences explain why all individuals don't look identical and these calculations are a measure of this. The differences are in the nature of the genes present in the population but not in the number genes present in the individual.

Coefficient numbers work when you have them calculated for a large number of individuals in a population, and can later see a relationship between the numbers and things like reduced health/fertility/vigor/size/performance and so on.

One example would be a chicken farm, and after having the number calculated for 1,000 chickens the farmer sees that at 33% COI the chickens have a drastic decline in egg production, so the farmer will try to inbred on his best producers, but still keep the number under 33%.

Today, In cases like with zoo animals, where you don't/can't raise so many animals but are trying to preserve or protect the species while doing limited breedings you want that COI number to be low.

On the other hand, labratory animals are often highly inbred on purpose so they represent a uniform animal model for scientific testing and experiments. 

With the dogs, if everybody bred to the sieger only, then, down the road the (COI) number would become higher, and that might be detrimental to the breed (population). This is why some breed clubs limit the number breedings one individual can have or eliminate the VA1 and pass out only a select class.

These are just some, and not all of the ways the calculations can be used.
I have no experience with Hardiman's coefficient, only very limited experience with Wrights, and F-statistics, but I am guessing you would need to use the same one for a whole population to later look at the data... kind of like inches and centimeters.

These links have rather good explanations of some issues with COI
http://en.wikipedia.org/wiki/Coefficient_of_relationship
http://en.wikipedia.org/wiki/F-statistics
http://en.wikipedia.org/wiki/Sewall_Wright
http://en.wikipedia.org/wiki/Hardy–Weinberg_principle
http://en.wikipedia.org/wiki/Animal_model

Can't find any reference to Hardman,  but you may get something out of this bibliographical

reference if you can track it down:

 

'Wright,  S.  1922   "Coefficients of inbreeding and relationship."  American National  (GSD Magazine ?)  56:330-8'

cited M B Willis  'Genetics of the Dog'.

Thanks Hundmutter,

As far as I can tell it is just the method. Hardiman's method is always calculated to 5 generatons, but I'm not convinced I have any unbiased and clear, easy to understand links to explain it yet.

They do say:
"Wright's Equation and Hardiman's Method are both based on the principle that the inbreeding of an individual is one half the relationship of its sire and dam, however the calculations involve different data and so the inbreeding coefficients produced by them are not interchangeable and should not be compared with each other."

http://www.highflyer.supanet.com/coefficient.htm