Archive | Livestock conservancy

The myth of ancient origins

3pharaohs

If there is one thing that is consistent among purebred animals, it must be the desire for ancient – and preferably exotic – origins. The latest and greatest may be desirable with high tech equipment, but we seem to prefer our horse and dog breeds well-aged. In the past I have enjoyed giving a presentation that pokes a little fun about breed mythologies. I am fortunate that my audiences have, so far at least, all been good sports, because this can be a rather touchy subject for a lot of people.

That is unfortunate, because many of the accepted stories about the origins of various breeds have not held up to closer scrutiny. As geneticists continue to analyze different populations, it is becoming clear that some populations are not remnants of an ancient group, but rather relatively modern attempts to recreate those animals – or in some cases, a romantic notion of what those animals might have been like. For those that do not have a strong attachment to the original stories, the truth can be far more interesting.

That is certainly true for the research being done by the Village Dog Genetic Diversity Project headed up by scientists at Cornell University. They have been collecting samples from hundreds of semi-feral dogs in remote areas in Africa. Their findings have been somewhat surprising.

African village dogs are not a mixture of modern breeds but have directly descended from an ancestral pool of indigenous dogs

Meanwhile, modern breeds that have been thought to descend from African populations, like the Pharaoh Hounds (above, photo courtesy of Wikimedia Commons) and the Rhodesian Ridgeback, clustered with Western breeds.

These results are consistent with [previous results] showing that Salukis, Afghan hounds, and Basenjis cluster with ancient, non-European breeds, while Pharaoh hounds and Rhodesian ridgebacks do not. Although this coarse sampling (3 countries) is suitable for detecting truly indigenous versus reconstituted ancestry in putatively African breeds, analysis including village dogs from more regions will be necessary to better localize the ancestral origins of these breeds.

What is interesting is that two of the three modern breeds noted as clustering with the non-European dogs – Salukis and Basenjis – still allow crosses to newly imported stock. (More information on that is available on the new Genetic Diversity page.)

This study is reminiscent of the one done a few years ago on the origins of the Arabian Horse. The author of that study, “Speculations on the origin of the Arabian Horse breed“, found persuasive evidence that the modern Arabian was as much a Victorian construct as it was a uniquely pure, ancient breed.

These results permit formulating the hypothesis that the Arabian horse breed was created from many different breeds and populations, and the concept of breed purity, might refer, at most, to the present population with a history that does not exceed two hundred years

Obviously there are not many ideas more scandalous in equine circles than Arabians being created “from many different breeds and populations” with a history that does not exceed 200 hundred years (ie., 1809). To imagine that carefully preserved purebreds are mongrels, while feral dogs bred without any human selection in the streets of Africa are free from outside “taint” and “pure” descendants of ancient ancestors, really does turn what we think we know about our animal companions on its head.

Edited to link to the full version of the Głażewska “Arabian origins” paper.

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You can’t pick your relatives

Cousins

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.

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Breed legend: PS – Thoroughbred, AA- Anglo-Arabians, SF – Selle Francais, TF – French Trotter, APPAL – Appaloosa, QH – Quarter Horse, AR – Arabian, LUS – Lusitano, PRE – Pura Raza Espanol, AB – Arab-Barb, BA – Barb, LAND – Landais, CAM – Camargue, POT-Pottock, PFS – French Pony, CO – Connemara, WAB – Welsh Pony, NF – New Forest, MER – Merens, BR – Breton, COBND – Norman Cob, COMT – Comtois, PER – Percheron, HAF – Haflinger, POIT – Mulassier, ARD – Ardennais, AUX – Auxois, TDN – Trait du Nord, BOUL – Boulonnais, FRI – Friesian, FJ – Fjord, SHE – Shetland, IS – Icelandic, PRW – Przewalski

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.

Nordics

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.)

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The Banjo Quotient

IbnRabdan5

My friend Carra McClelland recently referred to the issue facing the Abaco Barbs as the “Banjo Quotient”. Although the cultural reference might be lost on some of our foreign readers, for most Americans – especially those who, like me, grew up in the Appalachian region – it is a humorous way to refer to alarming levels of inbreeding.

Right now, even if all the remaining horses on Abaco are still living and can reproduce, the numbers represent high levels of inbreeding for the long term. There are three mares, of which two are mother and daughter. The relationship of all three mares to the stallions are not known, but they are presumed to be related. What’s more, the original herd of 35 was said to have been rebuilt from just three horses. That is what is known in genetics as a bottleneck. Bottlenecks reduce genetic diversity, which is essential to the health and fertility in animals. Abaco Barbs have apparently had at least one (extreme) bottleneck, and now are facing a second.

Unfortunately in horses, the obsession with the concept of “blood purity” can doom rare breeding groups like the Abacos. There is the perfectly understandable desire to preserve them. Unfortunately modern notions about what makes something a breed can narrow the options, as is often seen in purebred dog populations. This is particularly frustrating with horses, however, because there is often a disconnect between this relatively recent idea, and how horses have historically been managed.  In many ways it has more in common with the history of dog breeding than with that of horses – with a notable exception.

Arabians have been maintained as a breed much the same way dog breeds have been. There are known male and female founders, and their descendants are maintained in a closed registry. What Arabians also have in common with dogs is a fairly widespread acceptance of close inbreeding. The horse pictured at the top is Ibn Rabdan, a dark chestnut Arabian born in Egypt in 1917. He is relevant to the subject of Banjo Quotients in that he is the sire line for the Babson Egyptians. The only sire line. That’s because there are six horses that make up the “straight Babson Egyptian” bloodline: one stallion (*Fadl) and five mares (*Bint Bint Durra, *Bint Bint Sabbah, *Bint Serra I, *Bint Saada and *Maaroufa). The stallion, *Fadl, was by Ibn Rabdan. So were two of the mares. One of the mares, *Maaroufa, was a full sister to *Fadl. So while straight Babson Eyptian horses (like this one and this one) trace in all male lines to *Fadl (and therefor Ibn Rabdan), the horses are more closely related than that. Ironically, crossing the descendants of the same six already-related horses for close to 80 years is called preservationist breeding in that community.

Those involved in genetics would call it insanity. But this approach, which is hardly unique to those breeding straight Babsons, has come to color what many horsemen see as normal and acceptable.

And yet with modern genetic tools, we have options for preservation that were not available just a short time ago. In the past, outcrossing to broaden the genetic base for a breed relied on hearsay. That is how we got early Appaloosa breeders recommending that Arabians be used when available (in the 1930s, these were still relatively rare). It was thought that breeding back to Arabians would bring the horses back to the Barbs where the “spotting gene” was believed to have originated. I am sure images like this early 19th century Currier & Ives print of a circus “Barb” did a lot to encourage that idea.

3b50015r

Relationships can be determined by genetic analysis now. It is still a very new science, and often the results raise as many questions as they answer, but it does provide an avenue for objective evaluation of potential outcrossing groups. It might be too late for the Abaco Barbs, and some horsemen might still reject the idea of outcrossing at all, but for those willing to consider it the information might help preserve unique groups without creating family trees that don’t branch.

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