A Tentative Model for Astrex Genetics, by Helga Vierich
Genetics model for Astrex/ CPlop coat genes
Almost
all of the blue and black CPLops glow- like maybe they are or resemble
satin animals. I have gone over this systematically. I have been
thinking about this for some days now:
Normal Satin Astrex
Gene 1: hair shaft diameter/shape-alleles Sa sa sa/sax
Gene 2 hair shaftcurl/wave-alleles Wa Wa wa
Gene 3 guard hair/ less g/h-alleles G G/g g
Gene 4 Belly/neck curly -alleles bn bn Bn
Gene 5 Body Wave -alleles Ku Ku ku
Gene 6 Curl Solid/Curl spotting -alleles sp sp Sp/sp
Gene 7 Balding kit molt - alleles Bm Bm Bm/bm
Myohmy sasa wawa gg bnbn kuku spsp BmBm
China Doll sax/sax wawa gg BnBn kuku spsp BmBm
Isadora --same ---
kits with 48 hr baldness:s
sax/sax wawa gg Bn Bn kuku Spsp bmbm
The
two last alleles within the astrex “suite” (haha) are NOT
desirable, I'm thinking. At least not at this time. But both definitely
exist. The "curl spotting" causes the curls to be distributed on the
body in the way color is distributed on animals with English Spotting.
So you can have "patches" of curl in a field of straight fur, and you
can have "charlies" where the only curly fur is in areas like ears and
whisker bed where other genes do not allow curl to be expressed. We
have this in the CPLops. Not good but it has interesting future
possibilities - can you imagine a black and white with the black spots
curly and the white straight – it would not even be that neat an overlap
but what a challenge for the breeder some decades down the road!
As
for the balding kit gene - we have to wait and see how the coats on
these kits look in a year, and whether they bald with their next molt.
What I think happened in the Astrex is that the
original mutation was first found in the bigger Rex rabbits during the
1920's. From there, people
developed the Astrex breed, as a
variety of the Rex, and these animals all looked pretty much the way the
Astrex does here at my place. Now, the bigger Rex has evolved since
then, as breeders increased the body size and the thickness of bone.
the modern standard sized Rex rabbits, both here and in the UK, no
longer looks the same as it did in the 1930s.
In the
meantime, there were other importations that brought Astrex to the USA,
both in the 1930's and at later dates. These American Astrex lines
appear to have been lost. However they did not disappear without
leaving something behind. I believe there probably a lot of crosses
made to other Rex varieties to get new colours and to avoid too much
inbreeding. Animals of good type for the Rex breed but who exhibited no
curl may have been kept for breeding back into standard Rex lines. In
those days, knowledge of genetics within the general population was
pretty minimal, as DNA was yet to be discovered. Since the desired
curly coat genetically a bit more complicated than a simple single
recessive, (even though the only genetic work done on it to that point
in time, did, unfortunately come to this conclusion), people probably
got discouraged and gave up trying for curly rabbits and went back to
breeding straight coated Rex. But these recessive curl genes were still
lurking within the lines. A lot of these curly genes were continuing
to spread through the whole Rex genome and so inevitably got spread in
the Mini Rex genome as this breed was developed.
I have
made a case here for the linkage of the original “astrex curl suite”
with the harelike type of the early rexed rabbit. Now, just because
something is linked does not mean it cannot occur separately from the
other trait, only that it is harder to get than the two characteristics
together. . I think the linkages we see between the curl and the body
type may mean that these genes are located on the same chromosome. But I
think that full body curl gene is on another chromosome... or else it
is at opposite arms of the same chromosomes and so is more likely to
break off and recombine with something else (like the normal alleles on
the locii for the other genes) during meiosis. So the curly gene suite
gradually got broken up again.
And so now, sixty years
later, we do see these genes coming together in the right way -just by
random chance- to make that curly coat.. But for the Astrex that came to
Canada in the late 1940's, time has, in a way, stood still. They were
kept relatively pure until I got them, and I have tried to keep them as I
found them.
There ALSO has been sufficient time
for the linkages between body type and curl genes to be broken
repeatedly in the lines of Rex and now Mini Rex that have been evolving
in breeders’ hands in the nearly ninety years since the mutations were
first discovered. So when the curly coat reappears it may do so on
rabbits of all shapes and sizes.
However, here at
Golden Spike, this has not happened, since they were not much crossed
with anything outside their breed until I got them, and even then, I
tried to preserve them as I had found them, because I had made a promise
to the old lady I got them from.
I did however use some
Astrex to add certain colours to other breeds I was working on. Here,
in recent years, despite years “submerged” in several completely
different lines with a more “commercial” and compact shape a certain
slender elegant hare-like type and the full body curl have tended to
re-emerge together. This is only my impression, but it is very strong
impression. Or I would not even have bothered advancing this linkage
theory at all.
Whether the Astrex will ever recognized as a
breed by the ARBA is not known at the present time. I would like to
see the original type restored and written into the standard, but I
speak only from personal hope