When it comes to understanding our dogs, one of the most fascinating aspects is their genetic makeup. What breeds make up your pup, and how do they influence its appearance, behavior, and health? Dog breed genetics provides some answers.
Monogenic vs. Polygenic Traits
At the core of breed genetics is understanding the difference between monogenic and polygenic traits. Monogenic traits, as the name suggests, spring from a single gene. Think of these as the "on/off switches" in genetics. They lead to direct and often predictable outcomes. A classic example might be a specific coat color, where the presence or absence of a gene variant produces a particular hue in your pet's coat.
Polygenic traits, on the other hand, are more like a symphony, with multiple genes playing synchronized in an orchestra. It's not just one factor that determines the outcome, but a combination of several. Traits like a dog's size or temperament are shaped by this complex interplay of multiple genes. This means that predicting these traits can be more challenging, as they emerge from a myriad of genetic interactions.
Canine Selective Breeding History
Throughout history, humans have selectively bred dogs to emphasize certain traits, from hunting and herding to companionship. This selective breeding has largely been guided by complex, polygenic traits, rather than monogenic traits and has resulted in the majority of breeds we recognize today.
As human civilization evolved, so did our requirements for our loyal companions. From the swiftness of the Greyhound, perfect for vast plains, to the endurance of the Tibetan Mastiff in rugged mountains, breeds emerged as reflections of the environmental demands. Then came the agricultural age, bringing intelligent herding breeds like the Border Collie, and the Rottweiler, an adept cart-puller and protector.
However, it's not just about function; our bond with dogs delves deeper. Modern times ushered in breeds like the Cavalier King Charles Spaniel, not just for looks but for the warmth of companionship. In contrast to the relatively recent and aesthetic-focused breeding of cats, dogs stand as a testament to our shared history, making them as much a part of our cultural tapestry as our evolutionary journey.
Unlike cats, which have a more homogenous and recent selective breeding history, dogs have been selectively bred for thousands of years, resulting in clearer genetic distinctions between breeds in most cases. However, more recently established canine breeds share some of the same limitations from a genetic perspective as many cat breeds. These recently developed canine breeds may share most of their genomic information with other breeds and only differ by one or a couple of monogenic traits. One such example is the Biewer Terrier breed, which was derived from the Yorkshire Terrier breed. The main difference between the two is in the coat pattern. This means that these two breeds share almost all of their genetic information and it may therefore be challenging to distinguish between the two from a whole genome perspective.
Identity by Descent vs. Identity by State
Genomic similarity can be categorized in two ways: identity by descent (IBD) and identity by state (IBS). IBD refers to individuals sharing some of the same genetic information because they are related and one is a direct descendent of the other (ancestry), while IBS simply means that two individuals share some genomic similarity, but that may not necessarily be due to having a direct familial relation. IBS could indicate that your dog and breed X shared a common ancestor at some point (possibly even before the establishment of breed X), but not necessarily that your dog is directly descended from breed X. These distinctions also help explain why certain breeds might appear similar genetically, even if they appear different physically. It is important to keep in mind that genomic similarity does not always imply ancestry.
Interpreting Canine Breed Analysis Results
When you get your dog's Basepaws DNA test results, you'll receive genomic breed similarity scores ranging from 0 to 10 for different breeds. The higher the score for a specific breed, the higher the genomic similarity between your dog and that breed. Below are some common questions and answers about how to interpret your dog’s results.
1. Why Breed Similarity Score and not a breed percentage breakdown?
We decided to present breed genomic similarity scores instead of percentage breakdowns because percentages may be misinterpreted. For example, if your dog is 30% similar to breed A, it doesn't necessarily mean one of its direct ancestors was a purebred representative of breed A. Rather, it signifies genetic similarities which could stem from shared ancestors long before modern breeds were established. The Breed Similarity Score is less prone to such misunderstandings.
2. Will the test identify my dog as purebred?
We caution against using our DNA test (or any DNA test) to confirm whether your dog is a purebred. Different canine organizations’ breed standards don’t always have a perfect correlation with genetics. Although our test can show a high genomic similarity to a specific breed, it isn't a definitive measure of purebred status.
3. Why are other breeds listed in my purebred's results?
Breeds can share parts of their selective breeding history, resulting in genomic similarities. Thus, even a purebred dog might show low similarity scores to other breeds.
4. Why isn’t my purebred a “10”?
Purebred dogs usually score between 7-10. A score of 10 indicates a genome very close to ‘the average genome’ for that breed. Lower scores may reflect a divergence from the average but don't necessarily indicate non-purebred status. Some purebreds may have scores lower than 10 due to increased genetic diversity within the breed.
5. My dog is mixed; what will the scores look like?
A mixed breed dog may display genetic diversity not easily attributable to specific breeds. This is because they may have mixed breeds among their ancestors, as well. These mixed breeds are typically the result of dogs breeding freely, in comparison to human involvement through the selective breeding of dogs for specific characteristics. Your dog's "Polydog" score reflects the complexity of attributing its genetic makeup to a particular breed.
6. My dog doesn’t resemble any listed breeds; why?
Physical appearance might not always align with genetic breed similarities, especially if breeds have evolved specific characteristics after sharing a common ancestor with your dog.
7. What would a hybrid breed look like in the report?
Diving Deeper into the Accuracy of Dog DNA Tests
When discussing the precision of DNA tests for dogs, it's essential to appreciate the complexities and nuances involved. Our DNA testing method has an average accuracy of 98% for purebred dogs. This is an impressive number, however, it is an average, and the accuracy may vary from one breed to another.
Take the French Bulldogs, for example. They are a popular breed with a well-defined genetic background and a well-established lineage. Our DNA test for this breed has achieved 100% accuracy, meaning that if you have a French Bulldog, our test is likely to identify its breed correctly every single time.
On the other hand, consider the East European Shepherd with an average accuracy of 67%. Why is there such a discrepancy? The history of selective breeding plays a pivotal role here. Breeds with a longer and more exclusive selective breeding history tend to have more distinct genomic characteristics, making them easier to identify with high precision. In contrast, breeds with a more recent or diverse breeding history might share genomic similarity with other breeds, making them a bit more challenging to pinpoint accurately. The East European Shepherd was developed in the Soviet Union in the 1930s-1950s, making it a very young breed. These dogs were primarily bred from a combination of the German Shepherd and native Russian breeds such as the Laika, Caucasian Shepherd, and the Central Asian Shepherd, contributing to the higher genetic diversity of this breed.
While our DNA test provides an impressive average accuracy rate for identifying purebred dogs, it's important to understand that this accuracy may vary based on the breed in question. The intricate landscape of canine genetics, shaped by centuries of breeding practices, regional variations, and historical factors, ensures that the quest to pinpoint a dog's lineage remains both fascinating and complex.
Dog breed genetics is an interesting journey into what makes your pets who they are. Armed with this knowledge, you can better appreciate your dog's unique mix of breeds and the rich history they represent. Whether our furry friends are purebred, mixed, or a "polydog," they all hold a special place in our hearts.