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Posted by Bob Fengya on March 13, 2001 at 14:22:47:
In Reply to: Leucistic Black Rat posted by CK on March 09, 2001 at 09:19:34:
I have some old background information on the origin of the leucistic "Black Rat" that won't do much to solve the controversy - but may assist others in drawing their own conclusions.
In the early to mid-1980's a unusually-colored male E.o. obsoleta was wild-collected in N. Baltimore Co. MD. This animal was a deep grayish-brown dorsally, with burgundy overtones, venter basically unmarked save for some reddish and gray suffusion posteriorly. The eyes had an unusual copper tint to the irises.
The trait is apparently some form of hypomelanism,and is now generally referred to as the "Rusty" Black Rat.
The animal eventually wound up in the collection of Larry Rouch, formerly of Stafford, VA.
When I first got so see some F1 and F2 offspring ,
it was in the early '90's -- and was informed by Larry the the "rusty" trait was co-dominant, evidenced by the trait showing up in some F1 offspring of the original animal on a W/C normal, and furthermore, that the trait was linked to leucism as well.
He explained that he bred the "rusty" to a T- albino female Black rat - and upon backbreeding the double-heterozygous young that resulted from that union - he was shocked to find leucistic individuals in the F2 generation.
Now, here's where it gets interesting -- a few years later, I once again queried Larry about how he wound up with the first leucistic Black Rats, and he denied breeding albinism into the strain and merely stated that the leucism occurred spontaneously amongst "rusty X rusty" breedings over the years.
Many have stated that they feel the leucistic Black is just an artifact of the introduction of the same trait through deliberate crosses with lindheimeri - But the problem is, over the several years I had visited Rouch's VA business, I never saw Texas rats of any phase in his then-extensive colubrid collection. That's not to say he couldn't have taken a leucistic Texas rat on breeding loan in an effort to create the first Leucistic Blacks -- As he was selling some of the first leucistics he had available for around $500-$750 a pair, I imagine that some could have thought the creation of such an intergrade might be a good way to cash in on the then-exploding colubrid market.
I don't think Rouch was the type to bother with unscrupulous backcrossing as he was a frantically busy guy with a genuine passion for the hobby -- but who really knows? I don't know WHY he first explained the leucism as a result of combining T- albinism to the "rusty" trait - then later denied it - that certainly is suspicious. But it would be a simple matter to re-create the cross for anyone with the time/interest by simply breeding a homozygous "rusty" specimen to a T- albino, and back breeding the resulting generation to see if leucism is indeed a product of their double-heterozygous condition.
Such an experiment may throw a little more negative or positive light on the origin of the leucistic "Black Rats" -- the only thing I can say for certain is that the "rusty" trait has definitely been honestly represented amongst the descendants of the original Maryland male.
We may never know for sure regarding the occurrence of leucism in nominate obsoleta -- with all the misreprentation going on these days, every lucky guy with a new mutation is bound to have the new offering undergo heavy scrutiny.
Perhaps over the next few years, some more information will come to light regarding the origin of this trait in Black Rats - we shall see.
In the meantime, the leucistic Black rats I have seen have been uniformly gentle snakes compared to the generally irascible lindheimeri, and there seems to be a lot less incidence of the disturbing "bug-eyed" mutation associated with some regularity amongst clutches of leucistic lindheimeri.
Just wanted to throw some background onto this controversial Elaphe mutation --best wishes to all.
Bob @ Darkwoods
