The astonishing variety of traits, sizes, behaviors, and geographical distribution of dogs is a testament to the beautiful relationship humans and dogs have had over many thousands of years. To date, there are over 70 million unique genetic variations found across the canine genome, and that number continues to grow as more breeds are researched. The saying “variety is the spice of life” is also true when it comes to genetic diversity within breeds, as it can have direct and profound impacts on individual and breed-wide health and fitness.
Genetic diversity can be thought of as the “tool library” from which a breeder draws when faced with a new challenge, whether that is a new genetic disorder, exposure to a novel virus, or when seeking to create the next sensational working dog. The most obvious benefit of a more diverse gene pool is a reduction in the likelihood of matching recessive, maladaptive mutations being inherited from mother and father, leading to disease. As mentioned previously, all dogs, humans, and mammals in general carry a genetic load, so the question is not whether the dog carries disease variants, but which ones they have, and who they should be bred with to produce healthy offspring. There are also many other side effects of low diversity beyond risk of disease, including:
When viewing genetic diversity results for an individual dog, it is important to think about the result in the context of the breed and the genetic diversity present within all dogs. Zoo conservationists understand the need for managing species across institutions and have developed what are called “species survival plans” to maximize the genetic diversity needed for preservation of endangered species. With closed studbooks, we can think of kennels as being much like a conservation center for their breed, seeking to ensure the healthy future of their breed by cooperating with other breeders and kennels. An individual’s diversity result indicates how different the lineage of sire and dam are, which is sometimes called “internal diversity.” The internal diversity score of another dog might be the same number, but the specific markers will always differ between individuals.
Diversity can be measured in a number of ways. Historically, diversity has been estimated based on Wright’s coefficient of inbreeding, abbreviated as COI. However, COI is a calculated approximation of diversity based on pedigree, and does not directly test inherited genetic material.
Each breed will have different levels of genetic diversity, as well as different specific genetic variation that makes the breed unique, so interpreting individual results in light of the breed will help a breeder understand how their dog compares to the breed gene pool as a whole. Similarly, looking at breed diversity averages compared to all breeds and even wild canids like wolves helps to understand the long-term history of the breed and the inbreeding history it may have experienced. Many breeds have lost significant diversity in their formation, or during major events like world wars, so as most breeders intuitively understand, they inherit a legacy of breeding. The art is in combining dogs in complementary ways to both fulfill breeding goals for excellence, maintaining blood lines for future use, and avoiding genetic disease. It is a significant decision, and understanding genetic diversity is a key piece of the puzzle. A breeder inherits a legacy of breeding history, including population bottlenecks.
Genetic testing should never be considered the only measure of a dog’s merit to a breeding program. It should be viewed as one of many screening tools, and always seasoned with a breeder’s good sense of holistic goals for their kennel. Each breeder will have slightly different sensibilities about what they prefer in their dogs, which in an ideal world will encourage the preservation of the full variety of the breed to be enjoyed for generations to come. Some breeds are managed from within western registries, others are working landraces used for particular purposes in a specific region. The process of research and discovery is ongoing, and Wisdom is honored to partner with breeders around the world in delivering the latest in genetic science in service of the preservation and enjoyment of our dogs, now and in the future.
