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 Post subject: "THE LAW OF CORRELATION"
PostPosted: Thu May 01, 2014 3:03 am 
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Proud Rooster
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THE LAW OF CORRELATION

By Kenny Troiano

Copyright © 2014 by Kenny Troiano/Maximus Troy Publication

There is no doubt that marvelous things can be accomplished through the breeding of chickens. Selective Breeding is a wonderful mechanism for creating and improving a strain, but there are factors that can seriously limit what the breeder wishes to achieve.

It is often said that - "If we could just start with the individuals that we desire, within a few genera­tions, it would be easy to create the family of our dreams." But the reality is, no matter the quality of the individual, when breeding to create, maintain, or improve a family, it is necessary to consider many characteristics and traits at the same time.

For instance, breeders of American Games are continually dealing with fowl that have a never-ending tendency to go back to original type. In fact, they are bombarded with variations of characteristics that are always pulling their families back to the original traits of the Wild Jungle Fowl. At the same time, they are dealing with other factors in which some traits are directly affected by other traits.

What we are talking about here is a factor known as "The Law of Correlation.” And it’s one that is more important than you might think.

HOW IT WORKS: It is said that when a particular char­acteristic is closely linked, or connected with another characteristic, there is a correlation between these characteristics. This occurs when a breeder selects for a specific trait, but it’s a trait that has a tendency to generate changes in another trait, or many traits. Simply put, when you change one part of the body, you inevitably change another. It’s not just the relationship that exists between the birds overall form, but also its function or purpose. It may affect the various parts of the bird's body but also the purpose for which it was bred. For in­stance, there is a close correlation between the length of a cocks back, in this case, the shortness of the back, and squirrel tail. One is rarely found without the other.

CORRELATION OF CHARACTERISTICS: If each characteristic were absolutely independent of every other characteristic, the making of new varieties would be a hopeless task. The welfare of the individual greatly depends on the adaptation of its parts to each other (its overall form), and to the purpose for which it was bred (its function). Therefore, a family is established by being bred on a principle of selection of certain apparent correlations of parts, which occur so regularly that they appear to indicate an essential unity, making the group of characters act as one. Thus, the body, legs, neck, and head of a bird are correctly proportioned.

For example - a bird with a long body is likely to have a long neck, head, legs and wings. A bird with a short body tends to have short wings and a tail that is up over the back. We talked about this a moment ago. This is called “Squirrel Tailed.” A bird with very short, strong bill and broad skull is likely to be short and heavily built throughout.

To fully understand the impact of these correlations and their functions, just look at birds such as the Modern Old English Games, a bird bred exclusively for exhibition by breeders who did not understand the nature and makeup of the true Old English Game. Here we see an increased length in the neck and legs, which are quite out of proportion to the length and size of the body. As you can see, there is an unnatural relationship between the structural character of the bones and muscles. This bird is absolutely useless.

CORRELATION BETWEEN CHICKENS AND AMERICAN GAMES: There is, without a doubt, a general correlation of characteristics between all poultry. However, American Games are unique. They are very different from other fowl in their overall form and function. Just look at their conformation of body and color of plumage. No other domestic fowl has their stature or color. This is further evidence that Correlation does indeed exist, and makes possible their systematic classification.

CORRELATION AND SELECTION: American Games are excellent for studying features that are correlated, because they have many variable and easily defined parts. The form and size of the individual is often proportional to the form and size of its parts. For example, a bird with a long neck is very apt to be “rangy" throughout. Long necks are closely associated with having a long body, long legs, long wings, and a snake like head. The reverse is also true, where a bird with a short, compact body and neck usually has short, stout legs, short wings, and a short, overly compact back, and their head is short and compact as well.

Correlation is a big issue when it comes to the selection and breeding of American Games, for there are many characteristics that usually go together. Therefore, the breeder must be very aware of these characteristics when selecting the ideal bird.

EXAMPLE OF CORRELATION OF PARTS: Cor­relation can be valuable when fixing things such as their conformation of body. On the other hand, it may prove troublesome. It is true that cocks, which are high stationed, are not only extremely leggy, but they also have weak breast muscles. High station of leg and weak breast muscles are usually correlated, and it’s extremely rare for individuals that are medium stationed to have weak breast muscles. As you know, breast muscles are very important for proper wing function.

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PostPosted: Thu May 01, 2014 7:21 pm 
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Proud Rooster
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It seems to make sense from an evolutionary point of view that complementary characteristics would be correlated genetically either by a number of genes being strongly linked or by a particular gene prescribing a suite of complementary characteristics.
This has ramifications for those breeders who think that individual genes can be neatly excised from one genotype and inserted into another genotype.
I believe that even simple colour genes are often strongly connected with a host of other characteristics.


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PostPosted: Sat May 03, 2014 11:33 am 
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Proud Rooster
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Hi fuscipes, it is very interesting. The difficulties with the American game fowl is associated with the breed standard. Short back, long neck, short thighs etc. The more unnatural a breed standard is the more difficult it is to produce. The more primitive and natural a breed is the easier they are to produce. Examples are the Corriente cattle, the Soay Sheep along with the old Irish Goat also the Caspian Horse and the Spanish game.

Eddie


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PostPosted: Sat May 03, 2014 2:48 pm 
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Proud Rooster
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That tendency to produce the wild type is a very interesting phenomenon Eddie.
I guess that what we are talking about might be epistasis but that is a whole new frontier for me to explore.
As a bit of a digression it has just occurred to me that an intuitive understanding of epistasis might be the key to the success of those breeders who do well with limited numbers of breeding stock whilst others have to use the lotto and bulk feed supply approach.


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PostPosted: Tue May 06, 2014 9:58 pm 
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Proud Rooster
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fuscipes, in regard to reversion to the wild type, why has this not happened with the Norfolk island fowl ? Even American game that have become feral due to hurricanes on places like Hawaii never seem to fully revert. They tend to remain more stout and larger than a true Red Junglefowl. They also seem to retain the domestic colours even after many decades.

Eddie


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PostPosted: Wed May 07, 2014 12:20 pm 
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Proud Rooster
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Eddie, I can only guess what happens in feral populations. Complete reversion to wild type would of course not be possible in the absence of all the necessary genes. I suppose the founder effect and different evolutionary pressures might also come into play.
I was thinking more of the phenotypic expression of various traits but have to admit that I am not at all well informed about any of these things.


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