Re: A Colour Question re: E.o. obsoleta

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Posted by Paul Hollander on October 20, 2001 at 16:13:29:

In Reply to: A Colour Question re: E.o. obsoleta posted by patricia sherman on October 17, 2001 at 23:45:54:

: I'd really appreciate some comments about the colour of two of my E.o.o. yearlings.

: The parents are lovely black animals, with white chins and throats, tapering through progressively darker shades of opalescent grey along their bellies towards their black tails. Of the four babies, two are coloured very much like their parents, but the other two have very dark mottled brownish backs, and creamy yellow colouring where the parents have white. Their older sibling (3-yrs-old) is the same colour as the parents.

: In the each of the productive clutches laid by these parents, there were at least a couple of albino babies that died in their shells at or very shortly before the hatching date. I have no background information on the parents, but I believe that they may very well be littermates, and that the colour variance is due to shared genetic composition. What I'm wondering is whether or not this yellow (in one case it is becoming fairly bright as the snake matures) indicates that the parents are of intergrade ancestry. I'd also be interested in knowing whether the albino colouration is commonly associated with a lethal factor.

Very interesting questions. First, I'm not as up on black rat snakes as I could wish, and someone else might have better info than I do. What little I know comes from H.B. Bechtel's book, Color Variants of Amphibians and Reptiles. That has good pictures of a number of variations in the black rat snake. You ought to get the book, look the pictures over, and see if any match what you have. Bechtel also published a paper about black rat snakes in one of the 1985 issues of the Journal of Heredity. If you live near a university with a good library, you might want to check it.

I doubt that what you have is evidence of intergradation. I'd expect intergrades to have a considerable amount of variation, and that would include the parents, too. What you are getting seems more consistent with (but does not prove) the presence of a recessive mutant gene.

You may or may not have a semilethal mutant there. I haven't heard of any in snakes before. But I don't have complete information, and lethals have shown up in plenty of species, so why not snakes? OTOH, there may be some glitch in incubation technique or other environmental factor. I don't know.

Sounds like you have the beginnings of an interesting project there. Hope this is of some help.

Paul Hollander

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: <I>: I'd really appreciate some comments about the colour of two of my E.o.o. yearlings. : : The parents are lovely black animals, with white chins and throats, tapering through progressively darker shades of opalescent grey along their bellies towards their black tails. Of the four babies, two are coloured very much like their parents, but the other two have very dark mottled brownish backs, and creamy yellow colouring where the parents have white. Their older sibling (3-yrs-old) is the same colour as the parents. : : In the each of the productive clutches laid by these parents, there were at least a couple of albino babies that died in their shells at or very shortly before the hatching date. I have no background information on the parents, but I believe that they may very well be littermates, and that the colour variance is due to shared genetic composition. What I'm wondering is whether or not this yellow (in one case it is becoming fairly bright as the snake matures) indicates that the parents are of intergrade ancestry. I'd also be interested in knowing whether the albino colouration is commonly associated with a lethal factor.</I> : Very interesting questions. First, I'm not as up on black rat snakes as I could wish, and someone else might have better info than I do. What little I know comes from H.B. Bechtel's book, Color Variants of Amphibians and Reptiles. That has good pictures of a number of variations in the black rat snake. You ought to get the book, look the pictures over, and see if any match what you have. Bechtel also published a paper about black rat snakes in one of the 1985 issues of the Journal of Heredity. If you live near a university with a good library, you might want to check it. : I doubt that what you have is evidence of intergradation. I'd expect intergrades to have a considerable amount of variation, and that would include the parents, too. What you are getting seems more consistent with (but does not prove) the presence of a recessive mutant gene. : You may or may not have a semilethal mutant there. I haven't heard of any in snakes before. But I don't have complete information, and lethals have shown up in plenty of species, so why not snakes? OTOH, there may be some glitch in incubation technique or other environmental factor. I don't know. : Sounds like you have the beginnings of an interesting project there. Hope this is of some help. : Paul Hollander

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