[Jacob-list] Lilac/purity

[Neal and Louise Grose]

I thought that I should write back and clear up some of my thinking and statements. According to Mary Ellen, I have mostly "chocolate lilacs" except for one aged "grey lilac" that is sired by a ram of western stock. Dr. Sponenberg said once that "lilac is basically whatever isn't black". There may well be several lilac genes. What works for one may not hold for the others. I have excerpted Tara's letter here.

> This is going to be a little uncomfortable to say, but "lilac" expression
> > is "proof" that the animal is "purebred Jacob".
>
> Cool!  I can only say that your "uncomfortableness" really does help put
MY
> mind at ease.  :-/
>
> Yet another PLUS I figure for the lilacs if this color helps to prove a
measure
> of pureness.

Let's not get crazy here. "Purebred" is not the same as purity. You could make a case that all breeds start as crossbred, and then are reselected for type. "Purebred"
is relative, and has a arbitrary starting point. Purity is near impossible. What I am saying is that lilac is intrinsic to the Jacob genome. As a single gene, it can certainly get
shuffled around to somewhere else. I do not see lilac cropping up from other
breeds and know of no other breed where it is found. One theory is that lilac is a form of moorit. Having seen both now, I do not think so. If anything, normal Jacob "black" is a super dark brown (moorit?) and to my eyes, lilac is off tone from that.

> > When we cross our lilac Jacob sheep to homozygous white longwool sheep,
we
> > get piebald black and white lambs. I have done enough test crossing that
I
> > am reasonably sure that the black is the dominant Jacob black.

> To keep this all straight in my mind, I figure so far that lilac is
basically a
> simple recessive (l for lilac gene, B for dominant BLACK; homozygous "l"
(ll)
> gives pheno & geno lilac, "Bl" gives pheno black and geno lilac factor and
"BB"
> is dominant black pheno/geno).

OK, my explanation is going to seem a little goofy. What we have seen in our
flock refutes what Tara says and what is commonly thought. By the good
graces of our friend Betty who lent us a moorit Shetland ram, we will soon have a
few moorit Shetland X lilac Jacob lambs. I predict that they will be black and white, just like
the lilac X white longwools.

 Recessive genes are only expressed in absence of the dominant gene. The lilac is not following this model, instead we are seeing black expressed in absence of two lilacs.
My thinking is this: 
Instead of heterozygous black/lilac shown as (B,l) with these two genes at
the same locus, these may be at two different loci with (L) as a modifier for (B). "Lilac" is recessive to "normal non-lilac", not "dominant black". If (B) is dominant Jacob black, (L) is dominant "normal" and (l)is recessive lilac; then genotypes may be expressed as:

B,B + L,x = black, homozygous black
B,x + L,x = black, unknown genotype
B,x + L,l =  heterozygous lilac (lilac carrier)
B,x + l,l = lilac expression

[ This omits recessive black, dominate and recessive white, and piebald(s). The whole thing could quickly get too complicated to muddle through...]

"...Where the fading lilacs come from (maybe incomplete dominance or modification 
from another series or +/- factors, or roaning?), or..."

I am pretty confident that the fading/premature graying in lilacs is the standard premature gray that we see in the black and whites. People have not culled lilacs as readily as the black and whites. We have quite a few lilacs, and we do not commonly see premature graying.

"...Speaking about testing, has anyone DNA tested the Jacob to prove that it is NOT 
a cross developed historically from a goat and a sheep as some rumour to have 
occurred?  This theory has some merit in the phenotype of the Jacob, that there 
have been goat/sheep crosses that have lived and shepherds of old kept both 
together. .."

As I understand it, sheep and goats do not normally produce viable offspring. If they did produce live offspring, they probably would not reproduce, much like mules do not produce offspring. That said, the more primitive sheep crossed on more primitive goats can sometimes produce viable offspring. There are some reliable reports of Angora goats and Jacob sheep producing live offspring. I would go with the story that Jacob sheep are descended from Mouflon sheep, since (if I remember correctly) most sheep breeds ARE descended from them. Sheep and goats do have a common ancestor.

Neal Grose
Harmony, NC
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