I figured I should jump in here....
When I was first writing my genetics webpage I was waiting for people to try and attack my writings as inaccurate, and so far I haven't had any complaints. Chad, you are correct in that the hypo characteristic of true Ray Hine carrot tails is a dominant trait, and its pure form is the "ghost" morph that K&N Reptiles and Jodi Aherns are producing. I just talked to Jodi Aherns, and based on his observations of producing ghosts it sounds to be a dominant trait rather than a codominant, but we are still not 100% sure.
When I get a chance to revise my genetics page I will incorporate the dominant hypo addition. However, I fear it will only serve to confuse people further, and leave people thinking "Is my hypo a line bred or dominant...oh well, I give up. This stuff is just too confusing!". Realistically, if you had two animals side by side that exhibit equal amounts of hypo melanism and with a similar base color (yellow or orange), you can not distinguish a dominant ghost from a line bred hypo.
I am a biologist and have studied basic genetics and even taught it to my Bio 101 lab students, complete with a Punnet Square on how to create a patternless albino with a double het x double het breeding...man were they bored! I don't claim to be a genetics expert, and am always looking to add to my knowledge. It is my understanding that a co-dominant trait is one that has a "super" form, where the homozygous form (carrying two copies of the gene) looks markedly different than the heterozygous form (one copy of the gene), and a dominant trait to be one that doesn't have a "super" form (the homozygous and heterozygous forms look the same). The best example I can think of is with ball pythons...traits like pastel, cinnamon pastel, and mojave have a super forms and are codominant, while spiders do not have a super form (homozygous and heterozygous look the same). Mack snows are clearly codominant under this definition. It is unfortunate that the only distinguishing feature of a "super giant" is relative size, it isn't clear cut like a color difference.
Chad, do you have any examples of reptile morphs (any species) that fall into the other types of dominance?
Chad, I'm just curious, you said:
"a non-super codominant giant gene would look like elephantitis and a non-super codominant mack snow would have SECTIONS of yellow or red pigment not just an overall more yellow hue)."
Where did you get these ideas from?
I do believe that giants are a dominant gene for sure (and very likely a co-dominant) based on my experiences working with the morph over the last few years. I got a good group of giants soon after they were released, and raised a lot of "hets" and full blood giants (giant x giant breeding) to adulthood in 2003 (when they were thought to be recessive). For my ability to sell them, it was unfortunate the vast majority turned out to be males. But for my ability to gauge relative adult male size it worked out well. I couldn't understand why some of my giant "het" males (giant x normal-sized breeding) were getting to giant size, and some of my full blooded giants (giant x giant breeding) weren't getting to giant size. Recognizing this as a dominant gene explains my observations. The large, giant-sized "hets" were carrying one copy of the giant gene and expressing it with a larger phenotype, and the non-giant size, full blooded giants were the 1 out of 4 non giant you would expect from breeding two, one-copy giants together (Gg genotype).
Genetics can be a difficult subject, especially for those that may not have studied it in college (or skipped that class!). Unfortunately not all the "big name" breeders have a full understanding of even some basic concepts. I'll never forget one of the "big name" breeders told me years ago that if you hatch 15 eggs from a double het x double het breeding and didn't get the patternless albino or blazing blizzard the 16th egg was guaranteed to be the double recessive...ummm, no.
I always welcome friendly comments on my genetics page, so if you have any more suggestions let me know. Maybe one day soon when I finish my Master's thesis I can sit down and finish all the sections, and add sections on the new genes that have been discovered since I wrote the first version. If I really want to confuse people maybe I'll put in a Punnett Square of how to produce a super snow patternless albino!
Regards,
Steve Sykes
