>I have produced the Peanut Butter brooksi for the last three seasons and I have never produced a female Peanut Butter.

The Peanut Butter recessive trait starts out amelanistic but then gets more pigment and turns into a type of hypomelanism as it matures.



>To date ('99 when the first male Peanut Butter was produced) there has never been a FEMALE PEANUT BUTTER PRODUCED. I have been the only person to produce the PB morph in the last three years and I have also never produced a female PB.



>On a side note there is an unusual color difference in the het males and het females of this morph. Here is a pic which is shows a typical female het Peanut Butter and a typical het male Peanut Butter taken this year. They are both clutch mates from '03 and yet both are distinctively different in color.



>1)So, whats going on with this reccesive gene? How does the Peanut Butter morph start out amelanistic lavender and then turn hypomelanistc?



Quick answer: I'm not sure what is going on. But not everything is fully developed at birth. How often do you see a beard growing on a six months old baby boy? One possibility is that the peanut butter mutant gene interferes with normal development of the granules in the melanin pigment cells so that you don't see a significant amount of pigment until much later than normal. This may be wrong though. To really find out, somebody needs to get a bit of a peanut butter's skin at various ages and look at it under a microscope. It might be a good master's degree project for somebody with a leaning toward histology.



>2)Is it possible that recessive traits can be also sex linked?



Yes indeed. Two examples: sexlinked color blindness and sexlinked hemophilia in humans. Two more examples: web-lethal and brown in pigeons.



The common sex chromosome pattern in birds is for males to have two large Z chromosomes and for females to have a large Z and small W chromosome. Colubrid snakes are similar, except the W chromosome, while smaller than the Z chromosome, is pretty large compared to other chromosomes. See Robert J. Baker, Greg A. Mengden, and James J. Bull. 1972. Karyotype studies of thirty-eight species of North American snakes. Copeia 1972: 257-265.



I am not very familiar with brooksi kings, so please correct me when I go off track.



I wonder whether you are defining the peanut butter phenotype too narrowly. The het male in your first post looks like what I would call a normal brooksi, though maybe with a touch of brown in the back instead of jet black. The "het" female looks very different, much lighter than her brother. I've seen pictures of kings that I think are brooksi that look like her, but I don't recall any information about sex. If she is typical of the females with the peanut butter mutant gene, then you may have to define a male peanut butter mutant phenotype and a female peanut butter mutant phenotype (like her).



This rather reminds me of the brindle mutant in the black rat snake. From the pictures, the female brindles are lighter than the normal black rat snakes, and the male brindles are lighter than the female brindles. AFAIK, brindle has not been tested to prove whether or not it is sexlinked, though.



As Terry and Jeff have said, records and quantitative data are an absolute must for figuring out something like this.



I'd like to see the results of the following matings:

1) a peanut butter male x a "het" female like in the picture.

2) A peanut butter male x a normal female

3) A normal male x a "het" female like the one in the picture, and then cross the male x female babies, male babies to normal females, and female babies to peanut butter males.



Good luck with your future breeding. And I hope more people start breeding the peanut butters.



Paul Hollander

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