Monday, July 25, 2011

Is the Sorraia a Subspecies?

Sorraias - My Take on an Important Genetic Resource
D. P. Sponenberg, DVM, PhD, Veterinary College, VPI, Blacksburg, VA 24061

"At the outset, let me state for everyone that the status and future of the Sorraia horse is very important. The Sorraia is a pivotal component of the Iberian horse breed group. Controversy has arisen over just what this breed is, and its status throughout the world. Since I sometimes get misquoted over this issue, and frequently get lambasted, I thought I would detail my thoughts, opinions, and how I reached them.

A series of questions are important to deciding on what the Sorraia is, and what this means for its conservation and the conservation of North American Colonial Spanish Horses of similar type. I see these questions as:

1. Is the Sorraia a distinct subspecies of horse, or another Iberian breed of horse?

2. What is the relationship of the Sorraia to North American Colonial Spanish Horses?

3. How do we best conserve these genetic resources?

Sorraia - Subspecies or breed?

The answer to the question of the Sorraia being a subspecies or a breed can involve history as well as either DNA or bloodtyping evidence. Both types of evidence are important in making this determination.

Ruy D'Andrade is the one responsible for saving the Sorraia during the early 1900s. Some written accounts state that the original Sorraias were assembled out of feral or nearly feral herds in the Sor and Raia river valleys. Some of these accounts mention his picking the duns and grullos out of multicolored herds. Ruy D'Andrade himself discusses this in an article from the Boletim Pecuario XIII,3, 1945. The first herd he encountered numbered around thirty "more than half of which were light-coloured duns, some were grey, and many were striped." Of course, some of this depends on the interpretation of the word "grey", which might mean grullo. But, he does specifically state that many - not all - were striped.

In 1999 I was contacted by Dr. Maria Portas, a Portuguese veterinarian, about some details of horse color. Our e-mail correspondence went on to include a discussion of color details in the Lusitano, as well as some on the Sorraia. I asked her to check into the truth (or lack of) that the original Sorraias were assembled from herds that were variable for color. Her report back to me was that she had discussed this with d'Andrade's grandson, J. d'Andrade. He told her that his grandfather (Ruy) had indeed assembled the duns and grullos from herds including various colors. I don't know how much closer to the source I can get.

This is not a trivial detail, for a subspecies subjected to natural selection is not likely to vary in color, while remnants of domesticated populations (even if feral) usually do. While some wild animals do vary in color (wolves are a good example), this is not typical of most populations of nondomesticated hoofed stock.

An aside on color is that I have personally seen a bay Sorraia. This was in Bavaria while touring with Evelyn Simak, specifically looking at unusual horse breeds and colors. This was an individual specimen, not a part of a breeding group, but had been produced by a herd of pure Sorraias. Yes, I could have been lied to, but the horse was definitely Iberian, and in a location where this would be very unusual. And the people representing the horse as Sorraia had nothing to gain from falsely representing it.

Conversations with Dr. Gus Cothran indicate that the bloodtyping data support that the Sorraia is indeed an Iberian breed (this is hardly surprising), but that it lacks anything unique that would be indicative of subspecies status. The bloodtyping data indicate a fairly inbred population (which again is no surprise) with little variation. The Sorraia does have bloodtyping markers consistent with those in other breeds of Iberian descent, and shows no close relationship (on bloodtyping analysis, which does have some theoretical problems in this excercise) to any North American population. The Sorraia does share a reasonably rare bloodtyping antigen variant with the Cerbat population (which currently includes dark and roan horses but no duns).

Dr. Cothran also indicated that analysis of the D-loop mitochondrial DNA was not all that helpful in horses in assessing relationships and family trees. That said, he did indicate that the Sorraia did have some unusual D-loop characteristics. Other mitochondrial analysis might ultimately prove more useful, but it is important to remember that mitochodrial DNA comes only from the maternal line, so that a foal resulting from a Belgian stallion and a Spanish mare would resemble only the Spanish horse on analysis of mitochondrial DNA, and would give no hint as to the paternal side of the pedigree.

In the light of the historical and bloodtype evidence (which is much more than hear-say) I have to conclude that the Sorraia is not a subspecies of horse. This in no way detracts from the Sorraia's status as an interesting and extremely important rare breed, but it does not support its status as a subspecies.

What is the relationship of Sorraia's and North American Colonial Spanish Horses?

This is another important question. If the Sorraia were an important and integral founder of what are today's Colonial Spanish Horses, then this could be a breed resource of great immediate value and interest in Spanish Mustang breeding programs.

The historical evidence for the foundations of the North American Colonial Spanish horse include horses of many different colors. These are specifically laid out in various accounts, most notably the detailed one concerning the horses of Cortez. This, again, is at odds with a unique and uniform subspecies having been brought over to the Americas.

The bloodtyping evidence has also failed to demonstrate a tight link between today's Sorraias and today's North American Colonial Spanish Horses. A link, yes, but a tight link expected of a founder and its descendants, no. The available evidence supports that these two breeds are within an overall breed group of Iberian horses that includes other breeds such as the Criollos of South America, the various Paso breeds, as well as the Lusitano and Andalusian.

How do we best conserve these resources?

Strategies for conserving the Sorraia are perplexing at best, since at this point the Sorraia is a very small and very homogeneous population. At some point its vigor may be dependent on introducing some closely related stock, but that is problematic since no candidate populations are readily apparent. The evidence points to dun Colonial Spanish Horses as having only a superficial similarity to this interesting and important breed, and so should only be included in its conservation plan reluctantly if at all.

The available evidence also suggests that selection for solid colored duns and grullos among the Colonial Spanish Horses is not going to arrive at a point where these can be considered Sorraias. Such horses may have a superficial resemblance, the but underlying DNA and bloodtypes are not going to be Sorraia. Related, yes, but Sorraia, no.

The process of homogenizing horse populations for color is not without hazard and losses. When horses are discarded from breeding for nothing more than color the breed loses the potential benefit of some very good horses, and horses that are typical of the breed and its history. The North American branch of the Colonial Spanish Horse was always multicolored, and always moreso than other branches. There are a variety of historical, and some accidental, reasons for this, and it does remain a fact beyond mere speculation. The duns and grullos are no purer, no more Spanish, and no closer to some Iberian original than are their nondun relatives.

The process of homogenization on duns and grullos troubles me as a breed conservationist. I have seen it eliminate some interesting and useful horses. One especially tragic case to me was a beautiful blood-bay Sulphur colt who was to my eye very typey and had a great deal to offer. By the time of the SMR inspection of these horses this little bay was nowhere to be found - he was simply the wrong color in the wrong place, at the wrong time. He disappeared only because duns were favored.

The contention that the odd solid colored dun or grullo North American Colonial Spanish Horse is a Sorraia is fascinating to me, since most of these horses have full siblings that are bay or black. This means that the same mating is producing entirely different breeds, which makes no genetic sense.

One other issue is that of "type" in Colonial Spanish Horses, as well as in the Sorraia. The Sorraia is reputed to have a more uniform type than our Colonial Spanish Horses. This should come as no surprise to anyone, since the Sorraia is descended from relatively small numbers selected and bred by relatively few people. The Americas were first populated by a wide number of horses from a variety of Iberian strains. That foundation, coupled with the succeeding five centuries in various environments, assures that type is going to be variable.

How variable? I find it interesting that breeders have endless discussions on the finer points of Spanish type. These are well, good, and important. Also important to realize, though, is that even some of the more peripheral types, if put up next to a Morgan or Quarter Horse, are obviously a different type, and likely Iberian. Do not read this to mean that I think type is unimportant, for it is critically important to the conservation of the Colonial Spanish Horse. It is variable, but still distinctive and consistent enough to recognize and value.

As a summary, I have concluded that the Sorraia is not a subspecies, but is an integral component of the Iberian horse breed group. I have never stated that it is a mere color breed, for it is much more than that even though its current uniformity for color is from human, not natural, selection. Its relationship to any North American Colonial Spanish Horse is distant, and no greater than other breeds within the group. Both the Sorraia and the North American Colonial Spanish Horse are vitally important as conservation priorities, and only with clear thinking and appropriate conservation programs are they going to avoid extinction. To lose either or to discount the importance of either, is a great disservice to humanity."