Effective Population Size​

There are some key takeaways when using the principles of population genetics for making genetic change.  First, keep a variety of families for breeding, basically begin with least related dogs in the beginning. Then, use selection among offspring of the less related parents to identify those young dogs that are most likely to perpetuate the qualities you desire and keep those young dogs for breeding. Remember to keep a broad cross-section of young dogs across families, so genetic diversity can be maintained.

Second is to have short generation intervals, which will increase the rate of genetic change obtained per year. Use young dogs of the next generation as soon as possible to maintain reproductive capacity and to hasten genetic improvement per year. 

By applying these two key points and doing so by keeping Ne above 20, it is possible for a breed to realize only a slow increase in inbreeding per generation while also practicing selection. Try very hard to avoid matings that produce a rapid increase in inbreeding, which also causes a rapid loss of genetic diversity. Slowly increasing inbreeding over many generations of selection for a set of common goals, will concentrate the “genes” desired to perpetuate in puppies produced as the next generation. It will also ensure the long-term survival of the breed.

When looking at replacement breeders within a family, utilize estimated breeding values (EBVs) to help determine those young offspring that are most likely to perpetuate the goals established for a breed, then optimize matings by identifying mates that complement each other genetically while also producing puppies that are the least inbred.

• Click here for more information on EBVs.

One of the genetically most devastating moves a breed or breeder can make is to allow one male to sire most or all litters from which the next generation of parents will be chosen. Those puppies might be ideal, themselves, but they are all half-siblings, because they share the same father. This will result in a more rapid increase in inbreeding among puppies born into the next generation. By increasing the number of studs used, the rate of increase in inbreeding can be minimized. This could be accomplished by using frozen semen and/or by allowing males to have dual careers as both a breeder and a working dog. Collaborating with like minded organizations is an ideal way to expand Ne, by exchanging unrelated germplasm or puppies.

• How to share dog data in IWDR
• More on inbreeding and genetic diversity