The Soay Sheep Chronicles

The third in a three-part series

Part I:  our 2008 AI lambs, posted March 10, 2011

Part II:  our 2009 AI lambs, posted March 12, 2011

If you’ve been here recently, you know I  talked at length about the increased variety of coat color and pattern in British Soay sheep as a result of bringing in new genes via artificial insemination starting with the 2007-2008 lamb crop.  Last year, our 2010 lambs included several AI grandlambs and sure enough, the color fun continued.  Our light phase Mustard son (Dean) from the first year of AI served as one of our six breeding rams. I think I mentioned in the earlier color posts that as a lamb, Dean was a typical light phase Soay and he still is as an adult:

Dean, age 2 (Mustard son)

We hoped Dean would produce some pretty light phase lambs for us, and he did not disappoint.  First up, his twins out of Buttermere.

Hepworth & her twin brother Fouldon (Mustard grandchildren)

Next up, Ellerbeck x Dean twins,  another lovely light phase ewe lamb and … and …

Blakeney & her twin brother Barwick (Mustard grandchildren)

You may be asking yourself, “wait a minute, Dean is light phase.  Where did that dark charcoal son come from?”  Well, remember his grandsire, Mustard, carries the gene for self-coloration, and we know that whatever form of “self” came over with Mustard, it expressed itself in Buckley in 2009 and then Barwick in 2010. Are these four lambs the sweetest-looking Soay you’ve ever seen? Wow.

Since I have focused so far on the contributions made by the sires, it is only fair to point out that the mother of tan Hepworth and Fouldon is a plain brown ewe with extensive white spotting — Buttermere — but she is a carrier for light phase.  And so is the mother of tan Blakeney and charcoal Barwick, a plain brown ewe (Ellerbeck) with white spotting, carrier for light phase.  Isn’t color genetics fun?

Dean kept producing interesting colors for us right through the end of lambing last year. Remember our pretty black ewe Heywood from the 2009 lamb crop, daughter of Xanthoria, a plain brown ewe, and Curtis,the dark charcoal son of  Norris?  Last year we bred Xanthoria to Dean and what should appear but another black lamb.

Cley, age 7 weeks, Mustard granddaughter

Cley, age 3 months

Cley, age 6 months

There’s a video of Cley the day she was born if you’re interested in seeing how totally black she was when she came out.  She has the same unusual eye “ring” we saw in Cantrall and Buckley the year before, and the same white “dot” on her lip (but this time on her right lip) that we saw in Heywood.  But Heywood is out of Norris, and Cley is out of Mustard.  What’s going on here?  Genetic diversity at work!

One of the most intriguing parts about all this new color is what role the ewes play in the transmission of colors and patterns to their offspring.  Here is another picture of Xanthoria, mother of two black ewe lambs (so far), one a granddaughter of light phase Mustard, and one a granddaughter of brown Norris:

Xanthoria, mother of Heywood & Cley

Too bad you can’t see Xanthoria’s white belly and dark legs in this picture – typical British pattern and markings.  She was described as “very dark brown with black legs” as a lamb, so she must contribute color genetics to her black lambs.  But look back at the picture of her with Heywood.  Who knew she would throw black lambs?

Remember Keverne’s triplets from the 2009 lamb crop, the black/tan/chocolate trio? Look back at Keverne in the picture of her triplets; she also is a plain brown ewe with a white belly and white triangular eye markings.  Nonetheless, two years running she produced a light-phase lamb with eye rings, first Cantrall in 2009, and then Westerfield in 2010.  Here’s Westerfield:

Westerfield, age 10 weeks, Mustard grandson

Westerfield never was as “chocolatey” as Cantrall, and Westerfield’s eye rings faded as he matured, leaving him looking much more like a conventional light phase British Soay sheep.

Last year (2010 lamb crop) we also used a Norris son, Glen, as one of our breeders. His lambs are not as distinctive in color as the lambs out of Dean, but at least one of Glen’s offspring, a pretty ewe named Mattishall, shows some of the darker color we first saw in Norris’ daughter Vieva and his son Curtis, Glen’s father:

Mattishall, age 5 months, Norris granddaughter

I need to circle back to something I said much earlier in this group of posts:  our Norris and Mustard progeny and grandlambs are by no means all new colors.  In fact, our last lamb in 2010 came out a textbook mouflon brown, but as you can see, her “common” coloring slows her down not one bit:

Yarmouth, age 5 weeks, Norris granddaughter

Hmm, Yarmouth’s legs look pretty dark in this picture, don’t they?  I need to get back out into the gimmers’ pasture and see how her legs and face look by now.  Maybe she has some of the darker coloring from her grandsire after all.

It’s no secret that a lot of the lambs from the AI project, both generations, remain on our farm.  What else would you expect from a geneticist?  But we have sent AI grandlambs to new homes in seven states and British Columbia (so far) and we expect these ambassadors of diversity to contribute to the important work of genetic conservation and preservation in the flock throughout North America.

With 2011 lambing set to begin this week, who knows what new color adventures await us and where they will end up?  Stay tuned.

For now …

The first in a three-part series

Part II: more new colors in our 2009 AI lambs, posted March 12, 2011

Part III: more new colors in our 2010 lambs, posted March 14, 2011

In the last three years, the color palette of British Soay sheep in the United States and Canada has expanded dramatically.  Looking back, it is apparent that much of the variety of color and pattern seen in the ancestral Soay of St. Kilda was not represented in the six Soay sheep that emigrated to Quebec in 1990.  It was not until artificial insemination (AI) began in 2008 on our farm and on Kathie Miller’s farm that at least some of these “missing” genes came to be represented in the full Soay sheep in North America.

Genetic diversity in action: our 2010 British Soay lambs

The growing range and nuance in fleece color mark an intriguing new chapter in the life story of these sheep.  There is no better way to “talk” about the new colors than through pictures.  But first … a bit of historical and genetic context.

From 1990, when the first Soay lambs (Nougat and Carob) were born on George Berci’s farm near Montreal, until 2008, all the descendants of the original six founders looked pretty much alike:  brown fleece, white belly, sometimes a triangular white eye marking, sometimes darker legs, and occasionally a tan or white-spotted animal.  This homogeneity is not surprising, since five of the six founders– Maple, Butternut, Lily, Walnut, and Augustus — derived from a single flock in England and were substantially interrelated. Within that flock, where cousins bred to cousins, nieces to uncles, and so forth, there developed strong family resemblances, as illustrated by this early picture of the Berci flock, including some of the founders:

Berci flock in early 1990s

Without the introduction of any additional genetic input for about two decades, this homogeneous look would persist as descendants of the original flock expanded in number and spread geographically across the U.S. and back into Canada.  There were no self-colored animals, either black (dark phase) or chocolate (light phase).  Shades of gray seldom if ever appeared.

All of that changed when Gaerllwyd Norris and Gaerllwyd Mustard rode into town in little plastic tubes.

Portable Mustard (top) & Norris (lower)

The tubes contained semen donated by Christine Williams in Wales.  The relevant parts of the donor rams’ job resumes are as follows:

Mustard, whose RBST registration number S10149 can be seen on the right-hand end of the upper set of straws, is a light phase ram of the “wild” or “mouflon” pattern (white or light tan belly and eye markings, light eyelid rims, light lips).  His pedigree tells us that he carries the gene for self-coloration.  Depending on who the mothers are, Mustard can sire brown, tan, chocolate, or black lambs — either in person or long-distance.

Norris, RBST number S10979 on his straws, is a brown-fleeced wild pattern ram.  But we know from his pedigree that he carries the gene for light phase and may also carry the gene for self-coloration, so he also can sire both light and dark phase lambs, and possibly self-colored ones as well.  The genetic potential of Mustard and Norris is no accident; they were selected by Christine and Kathie for the AI project with diversity foremost in mind.

March 28, 2008, our first day of AI lambing, began with the arrival of plain brown mouflon triplets (Norris x Galice), all three in under ten minutes.  We were speechless but elated.  The AI project had worked!  In fairly quick succession we welcomed a pair of twins, light phase as expected since both parents (Mustard x Gala) are light phase, and then the color fun started in earnest.  Josephine, inseminated by Norris, dropped a black ewe, Vieva, the likes of which we had never seen.  Although Vieva looked black when she came out (sopping wet lambs often look darker until their moms get them cleaned off), on close examination we saw that she was not quite the same jet black common in many mammals (Icelandic sheep, border collies, many other mammalian species).  Instead, from the start she was more of a uniform very dark charcoal color, with her belly gradually lightening and lighter hairs appearing around her back end.  But no way was Vieva the typical mouflon pattern.  Here she is at birth and as she grew:

Vieva, age 1 day, Norris daughter

Vieva, age 7 weeks

Vieva, age 2 years, with sunbleached fleece

Another one of our first crop of AI lambs — Curtis out of Norris x Louisiana — also displayed the new uniform charcoal color and pattern, but not so dramatically as Vieva. As he matured, Curtis developed more eye margin contrast, and an impish white spot around his mouth, not reverting entirely to the more traditional British coloration, but not fully self-colored black, either.  Look at the contrast between Curtis and his plain brown twin Melvin, and then the contrast between Emmett, whose coloring could not be more typical, and his pasture buddy Curtis:

Melvin & Curtis (r), age 12 days, Norris sons

Curtis, age 2

Emmett (Mustard son) & Curtis (Norris son), age 1 yr

Nice pictures, but what does all this mean and why does it matter?

The increased variety of colors and patterns in our British Soay is a visual treat and always intriguing to my resident geneticist.  Even more important is the message this additional phenotypic variability sends about the significance of the AI project.  The new colors and patterns are just the tip of the genetic iceberg.  They are the only part of the infusion of new genetics we can see, but Mustard and Norris have introduced a great many other new genes.  We probably will never know the full extent or identity of all this new genetic material, or precisely what roles each new gene plays in the health and vigor of our flock. What we do know is that the enhanced genetic diversity resulting from the addition of Mustard and Norris to the list of founders increases the extent to which the North American flock reflects the sheep of St. Kilda.  It also re-affirms the need to support efforts to preserve and conserve this genetic heritage through careful conservation breeding.

As you can imagine, we finished our 2008 lambing season in a state of high excitement.  Little did we appreciate what lay ahead.  The second round of AI lambs in 2009 brought more surprises and even more color variety.  I’ll brag on that batch of lambs in my next post.

For now …