CORRECTIONS - PART XII & XIII

OF PEAS AND PUPS

CORRECTIONS - PART XII & XIII

PLEASE NOTE: This is a Correction

...ORDINARILY BEING CAUGHT IN AN ERROR is cause for some embarrassment, however, I am happy to have been caught by so many sharp GSP News readers. Happy, not because of these mistakes, but happy to have been caught because that is some indication that many are actually studying these articles, not just reading them. Many thanks to those who took the time to call these mistakes to my attention.

...THE CORRECTED FIGURE 51 APPEARS ABOVE. The Ib X Arta litter is till the most inbred U.S. Shorthair litter I have come across and it contains 87½% of the "blood" of Ib, BUT it has a coefficient of inbreeding of .375 rather than the .438 shown. Had, for example, Lucky II been bred to Ib their offspring would have had an F_x of .438 because sire and dam would be directly related by 87½% and since the F_x is half that relationship, we get .438 . Although Ib appears on the pedigree three times, there are but two generations of parent to offspring matings since Ib X Bunny was outbreeding with NO increase in like gene pairs. The fractions remain the same and give the % of Ib's blood carried by each.

...THE EASIEST WAY TO FIGURE THE DEGREE OF inbreeding of Coco and Meg is to realize that they are the result of a half-sib mating . The relationship between Ruffy and Sis is 25%, the F_x of their litter is one-half that or 12.5% but since both parents are also inbreed and thus themselves carrying more like gene pairs, that must be taken into consideration too. (See Fig 50) For that homozygosity, we use ( 1 plus F_R) plus (1 plus F_S) where F_R and F_S are the inbreeding coefficient for Ruffy and Sis. Ruffy 1.375, Sis 1.250. These figures added together and multiplied by the F_x of .125 for the mating of half-sibs shows us that Coco and Meg carry 32.8% more like gene pairs than do average Shorthairs...that they are 32.8% more prepotent.

...*THE CORRECTED FIGURE 51 contains the F_x data which should have been used throughout Part XIII when referring tot he specific dogs of that pedigree.

...ANOTHER ERROR APPEARING in Part XII was called to my attention by several. Figure 47 was an illustration using the beads for genes idea, to graphically demonstrate how inbreeding reduces variation while outbreeding increases it . We said that in mating of half-sibs (Artus & Becky), for the 16 gene pairs under discussion, that there could be but 44 genetically different littermates. THAT FIGURE SHOULD HAVE BEEN 54. In an outbreeding (Count & Duchess) there could be 23,328 genetically different littermates for these sixteen gene pairs. If YOU made these two matings (Artus X Becky and Count X Duchess) because of the outstanding qualities of the mates, which litter do YOU think would tend most to resemble their outstanding parents??

...WHETHER THE FIGURE IS 44 or 54 to 23,328, the basic facts remain unchanged. Outbreeding increases variation, inbreeding reduces it....put in other words, inbred pups will tend to resemble their parents more (for good or bad) their conformation, their style, their run, their noses...than will outbred pups, simply because of the amount of variation possible in the two breeding plans.

Copyright 2001. Dr. James G. McCue, Jr. All rights reserved. Postscript: And his legacy lives on in the German Shorthaired Pointers of today. May they always be healthy and bred with forethought and planning.

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