Woodland Creek Soay Rams

Woodland Creek Soay Rams
Soay Sheep Ram Assortment

Wednesday, April 25, 2007

Phenotype of Soay sheep carriers of agouti self-color gene

We had another Soay sheep lamb born at Woodland Creek Farm on Monday morning (23-Apr-07). Massena's Rosalina gave birth to a nice little ewe, Yaquina. The sire was Deer Park Hjemstad's Thor, a self-colored black NA Soay ram. Therefore, the ewe lamb has to carry one copy of the self-color allele at the agouti gene locus (controls coat pattern - self-colored (solid coat pattern) or wild (aka 'mouflon') pattern are the two choices found in Soay sheep). Here is a photo of day-old Yaquina.

While it is somewhat hard to tell in a photo of her standing by herself, she is quite dark and to me supports my strengthening hypothesis that there is a correlation between very dark coat colors and s-c agouti carriers. I have assembled a photo folder in my Picasa album showing those NA Soays that lead me to believe there is more than a circumstantial correlation. If you visit our web site and click on the Gallery button, then the Picasa album, you will find the folder.


Now don't misunderstand me - I'm not yet claiming I have proof that ALL NA Soay carriers of s-c agouti will be very dark, nor that all very dark NA Soays are carriers, but IF I had one that was very dark and it were possible that they were a carrier (one parent a known carrier, for example), I would say that it is a decent bet that the dark Soay carried it.
To me this may well explain the observation of many that the Blue Mountain stock is well-known for producing many "mahogany" NA Soays. Since the majority of the NA Soays with self-colored agouti alleles arose from stock from Blue Mountain, it is logical (and known) that many of these "mahogany" Soays carry the s-c agouti allele. This would also mean that if the phenotype of a heterozygote at agouti locus has a distinctly darker coat than homozygous wild agouti pattern, the wild allele is not fully dominant over the recessive self-colored allele.
Of course this is somewhat of a no-risk contention, because given a dark phenotype, one can never prove for certain that a Soay DOES NOT have a copy of the s-c allele, no matter how many lambs they produce.

No comments: