This post first appeared on September 2, 2011
In yesterday’s post I mentioned that breeders have a new way of finding closely related breeding groups. Genetic markers allow scientists to map out the relationships between the different breeds. This type of analysis was how the Abaco Barbs were identified as belonging the the Colonial Spanish breeding group. This can be really useful for feral herds like the Abacos where there are conflicting theories regarding the origin of the horses.
It is also being used to identify unique populations, with genetically distinct profiles, to target for preservation. This was recently done with a relatively large group of French breeds. The study is open access, so it can be read here:
Genetic diversity of a large set of horse breeds raised in France assessed by microsatellite polymorphism
Studies like this can turn up surprising results. In this particular one, the distance between two breeds that many would have assumed to be closely related – the Percheron and the Boulonnais – were actually quite distant. Both breeds are large, grey drafters from the same part of the world. Some historical accounts even suggest that the latter was used to create the former. And yet the Percheron is more closely related to the Norman Cob (technically a light breed) and the stout, silver dapple Comtois than to the Boulonnais. Here is a chart from that paper showing one method used to group the breeds studied.
Results like this challenge some of our assumptions about breeds. The authors of the study note that a few of the breeds clustered in groups that are different from French registry classifications. Those appear in italics on the chart. The Camargue, considered a warmblood breed in France, falls into the pony breeds, while the Merens, Halflinger and Friesian all cluster with the draft breeds. (To be fair the Friesian is a bit of an outlier there, as it is in almost any equine relationship chart.)
Sometimes the results of these kinds of studies vary a bit in the details, depending on the specific samples used (this one used a pretty large set) or the specific markers being studied. Others are really consistent from study to study, like the grouping of Nordic breeds, highlighted here in pink.
Of course, it is heresy in many Fjord and Icelandic circles to suggest that these horses are ponies. For that matter, the other group that falls into this same cluster (although not used in this study) is the Miniature Horse, which many admirers adamantly insist is not a pony either. Of course, it is hard to maintain that position when your closest relative is the quintessential pony, the Shetland.
Swapping the sections of the chart around, though, shows that the graphs for these Nordic breeds look more like the section of the graph for the other ponies than for the light breeds. Those are the breeds most Americans imagine when the word horse, and not pony, is used.
This is still really new science, but these kinds of papers have been appearing with increasing regularity. Hopefully they will one day provide an even clearer picture of how the different breeds developed and are related. But even with what we know now, it is possible to make more educated guesses about what needs to be preserved, and what might be the best path to take for those breeds with limited numbers. The new information will probably require that we lose some of the mythology that has surrounded many of our breeds, but the benefit should be healthier horses in the long term.
(Fjord image from Mirk-Stock and used with permission, original chart from the open access paper linked in this post.)
