[Jacob-list] Jacob lilac question

[Jacobflock at aol.com]

Fred here; still puzzled by lilacs.   Like Neil, there is a 50-50 chance this 
may be helpful but a 95% chance I am going to confuse the issue.  It has been 
my sense (also called non-sense) that the lilac genetics seem to parallel and 
include some of the concepts raised by Neil and, in part two, is void of 
unequivocal evidence.

First, the standard.  The Jacob is a ... a dominant black with a recessive 
piebald.  Then the standard goes on to say...the lilac is also a color.  What 
is a lilac and why is it part of the standard?  

The lilac GENE is a recessive trait.  To produce a lilac one must have a 
lilac allele on each side...expressed or a carrier (which may look like a 
black and white).  Two apparent B&Ws can produce a lilac; that is, each can 
be a carrier.  Two true lilacs cannot produce the 'usual' black and white.

The lilac COLOR is PROBABLY black.  COLOR is our perception of light 
reflecting off an object.  In the case of sheep fleece, the COLOR we see is 
the reflection of color pigment (melanin) in the fiber which vary in shape 
and arrangement. The black colors are a tyrosinase product (eumelanin); 
appearing as grey, blue, brown shade. The other color (of no import for 
Jacobs) is phaeomelanin which produce red through yellow.   It is my OPINION 
based on what I have read, that the presence of eumelanin (black-brown 
pigment) and phenomelanin (yellow-red pigment) in the same Jacob is extremely 
improbable.   

Neil recalled Phil Sponenberg's comment that the Jacob is "not black".  Is 
that a statement as to what is seen rather than what is.   It is my opinion 
that the Jacob is black (by definition) and the lilac color is a weaker or 
less dense eumelanin pigment which is reflected by light in a range that can 
be gray to 'blue' and deep black/brown to tan/light brown.

The posts from last year suggested some community confusion regarding 
identifying the difference between the lilac and the DOMINANT 'prematuring 
greying' gene that is observed in B&Ws.  Correct observation of the 'lilac' 
is a basic requirement and may not be easy in all cases.

Where does the varied intensity of the eumelanin arise?  Is it possible that 
a lilac carries a variant at the Extension locus OR carries a Dilution gene 
... black diluted to light brown or bluesih gray? Dilutes tend to have 
problems in some species; particularly in dogs. Is there a D locus for color 
intensity?  Dilution of black (gray) would be recessive to intense black.  Or 
is a lilac (unlike the black E dominant) an E recessive (E referring to the 
Extension locus which also controls the amount of eumelanin)?   The E 
recessive would explain both the recessive lilac genotype and the black 
intensity.  Ryder suggests the 'lilac' gray could be from the Soay (p. 
535ff).  

The lilac (like black) should also be supressed by the homozygous RECESSIVE 
piebald ss gene.  A Jacob color gene is more than one gene... and has 
multiple alleles... and just as the ss gene "stops" the dominant black (to 
place the white markings) in fixed and/or random ways, why not the lilac?  We 
often speak of specific breed markings around the eyes, muzzle (nose and 
mouth), knee and hock spots, etc.,  AND random breed markings around the 
body.  Lilacs have been described as having the lilac ring around the eye.... 
muzzle?...leg? markings; that is to say breed specific and random markings 
are BxW and lilac.  Lilac bodies are often associated with lilac eye rings.  
But other markings (muzzle and legs) may be black...a repeated observation.  
Which raises the next question, is the lilac a homozygous recessive (like the 
'standard black and white)? ... or is the lilac a heterozygous Spotted sheep? 
 

Second, the posts "THIS sheep looks like"... does not contain the information 
that would be most helpful... the PEDIGREE and details of ALL PROGENY.  So 
absent anything about the preceeding generations (known lilacs and 
black/whites and their markings) and ALL the progeny, there is only opinion.  
If the question involves the genetics of color, the answer is in the pedigree 
and ALL the progeny.

We have had lilacs with lilac markings and black leg markings.  Our 
experiments with lilacs are loaded with flaws and dead ends:  We acquired 
some lilac Jacobs in 1995 from a midwest broker that were represented as Hume 
sheep.  We started with Ole, a ten year old lilac and some lilac ewes.  

Mandy (lilac ewe) was bred by Ole (a lilac Hume ram with black leg markings). 
 Mandy had Andy a lilac ram and a ewe lamb named Sandy (a lilac with black 
leg markings).  Sandy was bred to Hot Shot (Hatch ram) the following year and 
produced Sweet Pea.  Sweet Pea carried the hornless gene (H+*hl) and was 
scurred.  This color test was comprimised by the scur (ho+*hl) which 
indicates a cross-bred trait that meant some non-Jacob genes.  Ole and 
another Hume ewe Florrie produced quadruplets: Kamir, Kamon, etc, etc.  
Again, this experience was compromised by Florrie's quadruplets (not usual 
for a Jacob but more closely related to the Boroola gene).  

Which brings me back to the lilac question and to repeat the suggestion: A 
group of ten Jacob breeders with six generations of Jacob lilacs (accounting 
for all progeny) with documentation should give a 95% confidence level as to 
the Jacob genotype.   The English do not like the lilac because they do not 
think it is a true Jacob..but they don't know what it is either.  We included 
the lilac as a Jacob (American) color.  Why?  Someone knows the answer.

Fred