Below is the dendrogram that displays the genetic relationships among the breeds in this study. (If you don't know how to read a dendrogram, there's a little tutorial here.)
For example, the Rhodesian Ridgeback shares haplotypes with a number of breeds: the Airedale Terrier, Irish Terrier, Irish Wolfhound, Greyhound, Doberman, Rottweiler, Great Dane, Boerboel, Bullmastiff, and Bulldog (see the figure below). According to the history of this breed, European breeds were bred with the Hottentot hunting dog of the Khoisan in Southern Africa, from which the ridge was inherited. That dog is long extinct, however, so it can't appear in this illustration of shared haplotypes, but the Basenji does, which probably shares some ancestry with the Hottentot dog.
The origin of the Schipperke has long been disputed, with some believing it to be most closely related to the Pomeranian, while others argue that it was developed by breeding down in size from the Leuvenaar, a black shepherd that is the ancestor of the modern Belgian Shepherd or Groenendael. From the haplotype chart for the Schipperke (below), it is evident that there is DNA shared with a number of toy and spitz-type breeds, including the Pug, Brussels Griffon, Pomeranian, and a few others. But by golly, the Belgian Shepherd and Tervuren show up as well, so there appears to be some truth in both stories!
One thing you need to be careful about when interpreting these haplotype charts. The analyses identify breeds that share blocks of DNA, but there is no way to know if breed A was crossed into B or the other way around. For instance, the Schipperke could have been used in the development of the Keeshond, or the Keeshond might have already existed and was used to develop the Schipperke.
Using these data, I've created a graph of the number of breeds by country and indicated the number with DNA information (below). For most countries, we have studied fewer than half the known breeds, and there are dozens of countries that are still completely off the research radar. Most studies to date have focused on the popular breeds registered by AKC and the UK Kennel Club, no doubt because those dogs are abundant and convenient. I personally think that these breeds, while familiar, are not representative of the great diversity of dog breeds elsewhere in the world. I hope that we can start including these less common breeds in future research, not only because they are novel, but also because most have not been subjected to the strong selection of breeding for show and we might find that they have very interesting genetic stories to tell.
Breeds by country
Breeds by function
This is fascinating stuff. It's hard to believe that we can sort through hundreds of breeds of dogs with just a bit of DNA! There is lots more to talk about in this paper that I will save for another post, but you should download a copy of the paper (below) and browse through it yourself.
Parker, HG, DL Dreger, M Rimbault, BW Davis, AB Mullen, G Carpintero-Ramirez, & EA Ostrander. 2017. Genomic analyses reveal the influence of geographic origin, migration, and hybridization on modern dog breed development. Cell Reports 19: 697-708. doi: 10.1016/j.celrep.2017.03.079. (Download pdf). Supplemental files: Table S1 (list of breeds); Table S2: Haplotype sharing totals; Data S1: Bar graphs of haplotype sharing.