I have produced the Peanut Butter brooksi for the last three seasons and I have never produced a female Peanut Butter.
that's odd. in birds, at least--and birds and reptiles are closely related--the sex-linked traits show up first on the females. With birds, here's why that happens: a sex-linked trait is one that occurs on the gene pair that determines gender. an added gene on that pair is what "makes" a female a female. that leaves only ONE position available for the sex-linked color morph gene. So if ONE gene is present on the pair, on a female it's the only color gene so the trait manifests itself even if the trait is a recessive one (there's no "other" or wild-type gene on that pair to dominate it); on a male, there's a corresponding and dominant "normal" or wild type gene on that same pair, so the male with a single gene for that recessive sex linked trait looks normal and is het. (OR maybe the females are single factor and the males double factor--see below)
at least, that's my understanding of how it works. paul hollander will be able to give a much better (and perhaps more correct?!) answer to this and my comments below. Paul?
>>The Peanut Butter recessive trait starts out amelanistic but then gets more pigment and turns into a type of hypomelanism as it matures.
this and the picture confuse me. the three snakes-in-hand are clearly hatchlings, so they're at the "start out" phase. but the snake on the left doesn't look anything like an amelanistic to me. nothing like other getula amels, at least: amel chain kings are white with yellow bands; amel cal kings generally the same, though i acknowledge the diff on the lavendar albino, or whatever they're called. still, that latter type would look more like other amels to most people, imho, than it would look like the snake on the left in the first pic, i'd think. so why call it an amel? is that what all amel brooksi look like? that would sure be a dramatic diff from the other amel getula.
>>The pic on the bottom shows a PB male on the left. A female het PB in the middle and a male het PB on the far right. Note that the het female (middle) is lighter than the het male PB (right):
Again, Paul will more intelligently address this than i can. But let me describe a "single-double-factor co-dominant sex-linked" trait I worked with with the Gouldian Finch, when i was breeding birds (I hope i got that nomenclature right)! Maybe this example will make something click as you try to sort out what's happening with your PBs.
In Gouldian Finches, the normal body color is dark forest green. A bird of the above type with only ONE of the mutation genes would be light green if a male, but yellow if a female. Why? It's as if the "yellow" gene "blends" with the normal green gene, on the male, to produce a light green, diluted green. And in fact these males were called dilutes. But remember on the female the other slot on that gene pair is occupied by the gene that makes her a female, so there's no blending, she just ends up yellow. Breed to produce a bird with TWO of the mutation genes, and you get males that are yellow bodied...those males would have two of the yellow genes on the same pair, no green wild-type gene to blend with it, so the full effect of the morph is shown.
(NOTE: if i've got any of this wrong, i apologize. I THINK it's an accurate explanation, while perhaps not entirely correct in the terminology, of what was happening)
I mention it because it could be what's happening with your PBs, except that in your case the males are lighter. Maybe those lighter males are double-factor animals? Maybe the sex-determination gene function is different in snakes than in birds? If they're "the other way around" then maybe the dark animal at right in the pic is NOT a het--maybe the parent you figured was a homozygous parent is a SINGLE factor example, not a double factor--in that instance half the males would get the gene from that father, half would get a gene from the mother (if the parent is a double-homozygous parent then all the males would get the mutant gene and if it's one of these single-double factor co-dominant traits, all males would show the effects, but if the parent is single factor (maybe you haven't seen a double factor male example yet?) then you'd get some males that were in fact het, and some that weren't, and because it's co-dominant the half that are "het" SHOW the trait, the other half don't carry any gene for it at all.
So it'd be useful to know more about test pairings you've done. What produced these three babies? What's the parentage of the three? What test breedings have you done with the parents that produced the first PB three years ago? The outcomes? What other babies were in the clutch with that first PB? And how have you paired them up? The outcomes? (I bought the first "yellow" gould genes into the U.S., and it took more than ayear of breeding and this kind of analysis of the results before we figured out what was going on...and the gouldians can reach reproductive age at 6 mos, whereas your snakes take a couple years at least, so 3 yrs might not have given you time to have seen enuff diff breeding results to have the data necessary, whereas in 3 yrs i was on perhaps the 6th generation of the finches).
1)So, whats going on with this reccesive gene? How does the Peanut Butter morph start out amelanistic lavender and then turn hypomelanistc?
well, one question would be whether it's actually a simple recessive gene.
also, an animal probably doesn't start out as one thing and end up as another, you're just describing appearances, not genotype. Example: amel hondurans--start out white and (red and yellow) or white and (orangeish-red and orangeish-red) but some of them gain a huge amount of yellow over time, end up with all the white turned bright yellow. And some don't. they're all still amels when they hatch and amels as adults, they didn't turn into something else. some other factors brought about some changes in them as they aged. so it would maybe be useful to describe color changes, not changes in terms that we consider genetic traits.
>>
>>2)Is it possible that recessive traits can be also sex linked?
sure. the black headed lady gouldian finch is a recessive sex-linked trait (or expressed in the other way, red-headedness is a dominant sex-linked trait. for practical purposes this means females of either type can be ONLY "pure"--that is, red with no black gene (remember the sex-determinant gene is filling the other spot) or black with no red gene. A male, however, can be 'pure' red and red visually, with a 2nd red gene filling the second slot, or red het/black, showing the dominant red gene but hiding or carrying the recessive black gene.
I hope this helps, and that when others smarter about these things elaborate (Ok, clarify!) something will click that helps you sort out what's happening with your critters.
terry
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.