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Another easy read on breeding populations
http://www.nationallacydog.org/forum/viewtopic.php?f=8&t=401
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Author:  Julie N [ Wed Feb 18, 2009 2:27 pm ]
Post subject:  Another easy read on breeding populations

This article specifically focuses on the issues inherent to small breed populations. This echos several articles we've already posted, but I like the way this one is pulled together. It stresses why attitudes and practices desperately need to change in the Lacy breed.

"Some breeders discourage linebreeding and promote outbreeding in an attempt to protect genetic diversity in their breed. It is not the type of matings utilized (linebreeding or outbreeding) that causes the loss of genes from a breed gene pool. Rather, loss of genes occurs through selection: the use and non-use of offspring. If a breed starts narrowing their focus to breeding stock from a limited number of lines, then a loss of genetic diversity will occur. The process of maintaining healthy lines, with many breeders crossing between lines and breeding back as they see fit, maintains diversity in the gene pool. If some breeders outbreed, and some linebreed to certain dogs that they favor while others linebreed to other dogs that they favor, then breed wide genetic diversity is maintained. It is the varied opinion of breeders as to what constitutes the ideal dog, and their selection of breeding stock based on their opinions, that maintains breed diversity.

The most important factor for diminished genetic diversity in dog breeds is the popular sire syndrome. The overuse of a popular sire beyond a reasonable contribution through frequent breedings significantly skews the gene pool in his direction, and reduces the diversity of the gene pool. Any genes that he possesses — whether positive or negative — will increase in frequency. Through this founder’s effect, breed-related genetic disease can occur. Another insidious effect of the popular sire syndrome is the loss of genetic contribution from quality, unrelated males who are not used for breeding. There is a finite number of quality bitches bred each year. If one male is used in an inordinate amount of matings, there will be fewer females left for these quality males that should be contributing to the gene pool. The popular sire syndrome is a significant factor in both populous breeds and breeds with small populations."

Read the entire article here: http://www.akcchf.org/pdfs/perspectives ... Breeds.pdf

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