Tag Archives | Appaloosa Project

Leopard Complex (Lp) test now available

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The official Leopard Complex test is now available for $25 from UC Davis. A paper detailing the causative mutation is expected in the near future. Congratulations to Sheila Archer, Dr. Rebecca Bellone and the Appaloosa Project on the discovery!

For more information on Leopard Complex, including some older posts that explain how it works together with patterning genes to produce the variety of appaloosa coat patterns, can be found by clicking on “Appaloosa” under the Categories menu to the right of this page.

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Belton patterned horses

This is “Gump.” He’s a Paint Horse that shows here in the Carolinas, and is the horse that first had me wondering about the possibility of a dark ticking pattern that was separate from any of the white patterning genes. As you can see, he has quite pronounced spotting on his face much like one might expect to see on a leopard. The problem is that were he actually a leopard as well as an overo, those spots would replace his bay areas, not his white areas. (For those just joining the conversation, the two previous posts explain this in much more detail.) I suspect those familiar with leopard patterns would also recognize that there area around his mouth doesn’t look right for the appaloosa pattern, either. It is too “clean”, with the spots and the white very clearly defined. If you cover his face so that just his muzzle shows, he looks like a pinto with “kissy spots” and not a leopard appaloosa.

So he is just a pinto. Here is a side shot to show the rest of his pattern.

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As this picture shows, he’s a frame overo. That white on the side of the neck and again on the side of the body are classic placements for that particular pattern. He probably also has one of the sabino patterns, since he has high stockings in the back. Frame does not typically add white to the legs, so frame horses with white legs are usually carrying something else in addition to frame. Since the various sabino patterns are widespread in riding horses, and especially in stock horses, it’s the most likely cause.

What struck me about Gump is that his pattern has a torn, angular look, which is quite different from his extremely round ticks.

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There is spotting on his leg white, too, though I did not manage to position myself for the best lighting in this photo. Like the spots on his face, these are round even though the rest of his stocking goes up in ragged angles.

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The character of the ticking and his pattern do not match.

That is particularly interesting to me, because most of the pinto patterns interact with one another. They don’t just overlap one pattern on top of the other. The presence of one tends to effect the appearance of the others. That overall influence gives most patterned horses a harmonious look. It also complicates matters for those of us interested in teasing apart and defining the different patterns, when the action of one mutation changes the actions of a second, unrelated mutation. Sheila Archer, of The Appaloosa Project, refers to this as patterns “talking” to one another. I have always liked that way of phrasing it, and would say that much of what I find most interesting about patterns these days revolves around those “conversations” between the patterns. The discordant patterns on Gump say that whatever is causing his ticking, it doesn’t seem to be “talking” to the rest of his patterning. That would at least suggest that it is something separate from whatever is causing his pinto pattern.

Gump sat in my “weird stuff” file for years, until last month, when a Facebook friend linked to this horse. When I first saw the image as a thumbnail, I assumed someone had found Gump. The ticking and even her base color is that similar! But that’s not Gump. That’s an Australian sport pony named Haley’s Comet.

Around the same time, another horse came to my attention. Her image was used on the header of the Paint Horse Connection, a quarterly newsletter that goes out to American Paint Horse Association members, and in an article in the Paint Horse Journal.

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Like Gump, she is a frame overo, but without the sabino-type leg white. And like Gump, she has the spots that are very concentrated on her face, compared to the spots on her body. Because her body has broad areas of white patterning, it’s even more striking on her.

That was what made me think of the Belton pattern in English Setters. They sometimes have that same kind of larger, more concentrated spotting on the face compared to the body.

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They aren’t all like that. One of the most interesting thing about the ticking (Belton) pattern in dogs is that it does have a lot of variation even within a single breed. But on a horse this kind of concentration on the face is quite unusual. Heavily concentrated dark ticking is odd in horses. Having it more pronounced on the face is stranger still.

You might notice that these horses all have a similar spotting arrangement, but that arrangement is rather different from Vision Morinda, the horse posted previously. Her ticking is more uniform, smaller and denser. It is hard to know, with so few horses like this, if these are variations on the same trait, or different things entirely. But having seen a handful of horses like this now, I know I’ll be looking at ticking more closely in the future. And certainly if any readers find horses with interesting spots inside markings or patterns that don’t fit what might be expected for a tobiano or one of the overos, please pass them along!

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More thoughts on ancient appaloosas

It has been exciting to see that the recent paper on horse color and cave art has gotten a lot of attention in the mainstream press. It is great to see scientists like Rebecca Bellone, the lead researcher from The Appaloosa Project, recognized for their work. I also love the idea that an area of study traditionally connected with agricultural and veterinary science could be used to better understand seemingly unrelated fields of archeology and art history. It makes sense that in understanding the horse, whose history is so intertwined with our own, we gain insight into ourselves.

That is the larger picture. From the smaller picture that is the focus of this blog, the study offers some big surprises.

To adequately explain, I’ll need to expand on the comments that were made in the earlier post on gene locations. In 2009, the paper “Coat color variation at the beginning of horse domestication” was published. In that study, ancient remains were tested for the presence of color mutations. The range of tests available at the time included:
Extension (black/red)
Agouti (bay/black)
Cream
Silver
Frame
Sabino1
Tobiano

Those tests determined that all but the frame gene were present among the early domesticated horses. That is certainly in keeping with the theory that frame is a New World mutation. It also showed that in the wild populations – horses living somewhere between 15,000 and 3,100 BC and predating domestication – the only mutation was black. Black horses were found among the wild populations in Romania, Ukraine and the Iberian Peninsula. The other populations, which included remains from Siberia and Germany, were entirely bay.

The two patterning genes, Tobiano and Sabino1, were found in remains of domesticated horses. That is in keeping with the idea that spotting mutations are linked to selection for tameness. The Russian Farm Fox study is often cited as a good example of this, but most people familiar with newly introduced “pocket pet” species have seen this in action. It usually doesn’t take long after a species becomes popularized before spotting patterns begin to appear.

What makes the cave painting study so fascinating is that the appaloosa patterning gene was found in a wild population. And it wasn’t just one horse. Of the thirty-one samples, six were carrying the mutation for leopard complex (Lp). Were someone to assemble a random sampling of modern domestic horses, it would be unusual to say the least to find that kind of ratio of appaloosas to non-appaloosas.

Also interesting is the fact that while there were six leopard complex horses, there were no chestnuts. Chestnut is found in the Przewalski Horses, where it has been documented as far back as the early twentieth century in skins taken in Mongolia. In the cave art study, there was a single Romanian sample that tested as carrying chestnut, so the mutation did exist at least in that population.  It would seem to be rare compared to leopard complex, and not nearly as old. The German samples with leopard complex date between 15,000 and 11,000 BC, whereas the Romanian with the chestnut allele is 4,300 BC. This is interesting when one considers how in many primitive European pony breeds, chestnut is non-existent, or when found is considered proof of foreign influence. It also gives a certain level of credibility to claims made by both Gypsy Cob and British Spotted Pony breeders that appaloosa coloring was once part of the native population.

It is also interesting that this mutation occurred in a wild population, and was obviously perpetuated, despite the fact that homozygous leopard complex horses have a defect. They are blind in low-light situations, which should act as a negative selection factor. None of the horses tested as homozygous for leopard complex.

Limitations

As exciting as the results of the study are, some limitations have to be remembered. Probably the most important is that this was a really small sample set. Getting usable genetic material from ancient remains is difficult, which is why there are only 31 samples. Broken down by time frame and geographic location, you end up with even smaller groups. These tests can certainly confirm that a mutation was present, but it is hard to draw any firm conclusions about the whole of the ancient horse population based on so few animals.

We also only have a partial picture, because we only have a partial set of color tests. The previous study, done in 2009, used some of those same samples. Without the leopard complex test, which was not yet developed then, we only knew that the wild horses were bay or black. With the new test, we now know that, yes, they were bay and black – and some where varnish roans (leopard complex). We don’t yet know if they had the patterning genes that turn leopard complex into true leopard patterns, though certainly the cave paintings would suggest that this was so. Likewise, we assume that the original horses were dun, since that coloration is associated with wild equines, including the last remaining wild horse. A completely reliable test for dun is not yet available, so that part of the picture is incomplete as well. Those bays and blacks, now known to in some cases be bay or black varnish roans, may later prove to be dun and grulla varnish roans – or not!

We know they were not silver or cream, since those can be and were tested. But as new color tests are developed, we may later learn that some of those horses were also roan or grey or splash. It may be that varnish roan will eventually lose its place, but for the moment it is the oldest tested pattern.

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