[Jacob-list] Re: Lilac question

[Grose]

First off, it does not come as any shock to me that the nice lady in Scotland had never heard of an off color Jacob sheep. With all due respect, until about 1965, no respectable Holstein breeder had ever had a cow that threw a Red and White calf AND I happen to know that there were some outstanding Red and White herds started with calves that were given under the understanding that NO one would find out where they came from. That is not to say that your friend is being disingenuous, just thank goodness they sent there culls to us.

Getting back to my example of black and white crossbred lambs out of a lilac Jacob parent, there were some questions about the longwool parent. The original group was made up of 4 Lincoln/Finn ewes and a stunning looking Cotswold/Finn ram. They have been maintained as a line -bred group since. They are white and colored and show a simple dominant/recessive relationship between the white and colored genes. The color in these guys varies from silver[blue?] to oatmeal, and not the saturated black of the Jacob sheep. I left out the lambs from colored FinnX ewes from my analysis. All of the lambs from the cross of white FinnX parent and lilac Jacob parent had black with white markings, and the color was the saturated black of the dominant black [Extension locus, Ed allele in Ingrid's book]. These lambs varied from 95% to 50% black. 
I need to back up here and give credit where credit is due. This situation was presented to Dr. Phillip Sponenberg 2 years ago and he gave a likely solution. In Jacob sheep, "lilac" is "not black". The lilac gene "masks" the expression of the black gene/s. In the crossbred lambs in the example above, it is probable that the lambs could not ALL have expressed a black allele from the FinnX parent. This may provide a possible mechanism for the variations in lilac expression and in explaining the lilac circle around the eyes of heterozygous black/lilac Jacobs. The variations that we see in lilac Jacobs may be due to the variations in the underlying black. In this situation, my guess is that the locus for lilac is different than the locus for black. In other words, instead of lilac represented as ElEl and black as EdEx, lilac would be EdEx+LlLl  and black would be EdEx+LdLx [or something].

This would also go some way to explain why this would not show up readily in original populations. I hope this makes some sense, it barely does to me.
                           
                                       Neal Grose
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