Suze, it is wise to always keep an eye out for any linkage in either good or bad traits. Didn't Sheila Smith recommend keeping pups with color on the elbows because she found that this marking is linked to some excellent traits in her lines? This is the sort of thing that one notices. It doesn't necessarily mean that it would hold true for every line, but it does for her dogs. Another thing, linkage can be broken by crossing over of the homologous chromosomes during meiosis. The further apart the two genes are on a chromosome, the more likely the linkage will be broken with greater frequency. Linkage shouldn't be viewed as a rule, but as a tendency. Even closely linked traits can become separated if there is a chromosome that does not carry the linkage in the gene pool. This happened in Cockers with a buff Cocker that inherited the heavy coat that had been linked to black coat color.
If the desirable trait is bred for extensively, there is a danger that the chromosome that does not carry the linkage will be lost from the gene pool. That was what happened to the Dals. They were bred for perfect spots so long that they eliminated all chromosomes possibilities that did not carry the linked uric acid trait. It does make you wonder what defect is being increased by all the accent on longevity. Breeding animals is very much like stopping a leak in an earth dam by poking your finger in the hole. After a while, you run out of fingers. All the best, Susan Cochran ----- Original Message ----- From: "Susan A. Schlenger" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, June 18, 2002 10:19 AM Subject: Re: [CKCS-L] Type vs health > Hello, Susan, > I for one, am not ignoring this fact. I think we continue to hope that > with the unraveling of the genome we will see some clues of what links > we do have to genetic flaws in our breed. It is the best hope we have > of discovering how to fix the problems. > > I do wonder, however, what will happen if we discover that one of our > most desireable traits (such as large, round, deeply pigmented eyes) is > linked to one of our least desireable health problems. I think many of > us will lay down our heads and cry long and hard. > > Wouldn't it be fabulous if we found that a commonly ignored faults such > as slight cowhocks was a genetic link? > > > Suze (the ever hopeful) > > Susan Cochran wrote: > > > > However, it is common to have genetic traits that are linked to certain > > conformation traits. Linkage is the fact that genes for different traits > > that lie on the same chromosome are inherited as a unit. That is why the > > uric acid defect is linked to the desired spotting in Dals. These two > > genetic traits are close to each other on one chromosome. > > > -- > Suze at Llawen Cavaliers > "...I have seen that in any great undertaking it is not enough for a man > to depend simply upon himself." -Isna Ia-wica > "Thought comes before speech" Luther Standing Bear > > ========================================================= > "Magic Commands": > to stop receiving mail for awhile, click here and send the email: > mailto:[EMAIL PROTECTED]?body=SET%20CKCS-L%20NOMAIL > to start it up gain click here: > mailto:[EMAIL PROTECTED]?body=SET%20CKCS-L%20MAIL > > E-mail [EMAIL PROTECTED] for assistance. > Search the Archives... http://apple.ease.lsoft.com/archives/ckcs-l.html > > All e-mail sent through CKCS-L is Copyright 2002 by its original author. ========================================================= "Magic Commands": to stop receiving mail for awhile, click here and send the email: mailto:[EMAIL PROTECTED]?body=SET%20CKCS-L%20NOMAIL to start it up gain click here: mailto:[EMAIL PROTECTED]?body=SET%20CKCS-L%20MAIL E-mail [EMAIL PROTECTED] for assistance. Search the Archives... http://apple.ease.lsoft.com/archives/ckcs-l.html All e-mail sent through CKCS-L is Copyright 2002 by its original author.
