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haplotype length to estimate when other breeds were crossed or diverged. For example, the written history of the Golden Retriever says it dates from crosses to other breeds between 1868 and 1890. The haplo- type sharing between it and the Flat-Coat predicts it diverged around 1895. In anoth- er example, dating using haplotype sharing indicate all of the Bull and Terrier breeds date to 1860-1870, a heyday of dog fight- ing in Ireland. The researchers caution that such dates are approximations and can be influenced by selection for or against vari- ous traits as well as population size at the time of the cross. Most breeds within the various clades share haplotypes that point to creation during or since the Victorian era when we also know historically “pure” breeding became in vogue. However, the general lack of haplotype sharing between clades suggests that these general families of dogs existed long before. The data sug- gest the “Asian Spitz” and “Mediterranean” clades are the oldest, in line with previous studies that suggest the earliest dogs came from Central and East Asia. The classification may not always be intuitive, but that’s part of its value. For one thing, breeds that are genetically simi- lar are more likely to share diseases inher- ited from a common ancestor. Everybody knows Collie breeds are at risk for Collie Eye Anomaly, for example, but why do some Nova Scotia Duck Tolling Retrievers get CEA? It turns out the breeds all share the same identical-by-descent haplotype— and the genetic evidence suggests that Col- lies and/or Shelties actually contributed to the formation of the Toller. It goes the other way. Many of the UK Rural breeds share the MDR1 (multi-drug resistance 1) mutation. But it’s also been reported in the German Shepherd. The evidence shows the UK Rural breeds are linked to the GSD through the Australian
Shepherd or its predecessor, offering a clue to the GSD’s make up. It also explains the presence of MDR1 in the Chinook, which haplotype evidence shows has both GSD and Collie input. More importantly, breeds previously thought to be unrelated may now be suspect for diseases found in fel- low clade members. The Xoloitzcuintli also shares haplotypes with the GSD and Collie, leading to speculation as to whether they should be tested for the MRD1 mutation. More oddities exist when it comes to the “New World” clade, which unexpect- edly stars the German Shepherd. It’s pos- tulated that the GSD or an ancestor may have been introduced into New World breeds such as the Xolo and Peruvian Inca Orchid. In fact, the ancient hairless breeds show evidence of extensive crossing with European herding breeds, which would have been brought over by early settlers with their livestock. This seems to be the case throughout the Americas. Although Native American dogs have been present for at least 10,000 years, with the possible exception of the Carolina Dog and maybe one or two others, they are largely thought to be extinct. However, the presence of American breeds with no European hap- lotypes suggests that the Native American dogs could live on through the “American Terrier” (Rat Terrier, American Hairless Terrier and Toy Fox Terrier) and “Ameri- can Toy” (Chinese Crested and Chihua- hua) clades. Most breeds we actually think of as “American” are genetically mixes of European breeds. This research not only has implica- tions for many of the individual breeds included, but for our entire understanding of domestic breed distribution and devel- opment. We’ve always been led to believe that groups of similar looking or function- ing dogs arose through selection and were then spread throughout the world by trad-
ers, explaining how Salukis begat Grey- hounds, for example. But it turns out that’s not how it was. This research suggests that instead of developing in one area and spreading from there, the same changes occurred in multiple locations throughout the world, leading to dogs similar in phy- sique and function but not in relationship. Thus you have the Saluki, the Greyhound and Xiang, all of which clearly fit the Sight- hound mold—and apparently arose entire- ly independently of one another. If that is indeed the case, it explains some things, such as how the Saluki and Afghan Hound are behaviorally so different from the Greyhound or Whippet, but opens up even more baffling questions. For example, why do the Saluki, Greyhound and other “Sight- hounds” share so many odd blood param- eters, such as high hematocrit and low platelet count? It’s possible that they, too, arose independently simply from the need for speed...and if that’s the case, what oth- er physiological attributes might also have arisen independently to support function in unrelated breeds? Will this change the way we judge or breed dogs? No. But what if we find our- selves in a circumstance where we must cross with another breed, such as was done with the Dalmatian and Pointer? It turns out that cross was within a clade, which is probably one reason the result worked out as well as it did. It can also change the way we select dogs as pets. Last weekend I was approached by a spectator who was considering a Saluki, as he had loved his recently deceased Whippet’s personality so much. He was surprised to learn they were light years away in temperament. Now we may know to stay within a clade if we prefer one temperament type over another. For the entire research article go to http://www.cell.com/cell-reports/full- text/S2211-1247(17)30456-4.
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