Howdy ya\'ll,
Not sure how I missed this discussion... genetics is my favorite topic, lol. I\'d like to point out a few things regarding \'Dominant white\', \'recessive white\' and \'blue\', as well as the structure of the Seller\'s site.
John, Lee set up the hierarchy as such that genes are grouped in to subclasses within their main grouping. In plain speak, Dominant white may be in with other genes within that general grouping, but it will be within it\'s own specific sub-group along with \"only\" the associated alternative alleles. Unless Lee has changed the structuring in the last year or so, the specific family groupings are all in the same box. So.... Dominant white \"I\", wild type \"i+\" (normal coloration), Smokey \"I^S\" and Dun \"I^d\", are all the documented allelic alternatives at \"this locus\". \"Bl\" blue may be within the same main grouping, but that doesn\'t mean it is found on the same spot on the chromosome or even that it\'s on the same chromosome. You can tell what is related to what by the \"tab field\" that each gene is listed in.
Regarding \"how\" each of these genes work, Dominant white AND the alternative alleles in it\'s family are very specific in their functionality, they are \'dilutors\'. Blue is also a dilutor. Recessive white on the other hand is an \"inhibitor\", which means that it actually stops the production of pigment all together. It helps to know where and when these genes work also. Both types of pigment are produced by melanocytes, which are highly specialized cells that come from the same nerve tissues that form the brain and spinal tissues. Very early in the embryo\'s development the melanoblasts break off from the lower (back) portion of the neural crest (pre-brain tissues) and \"travel\" throughout the body, depositing themselves in connective tissues such as the skin and the areas where feathers grow from. Once firmly rooted they become melanocytes which produce the pigment granules that we call \"color\". Inhibitor type genes \"stop\" the production of pigment in a unique way, as most of the melanoblasts don\'t survive long enough to become melanocytes, so they won\'t produce pigment at all. There can be negative effects of this as can be seen in recessive white cats (and many other recessive white animals). Some recessive white complications are deafness and in some cases blindness. Quite simply put, in some cases the genetic cause of recessive white is so strong in it\'s affects that melanoblasts die before implanting in the eyes or ears to become sight tissues or hearing tissues. In extreme cases there can be major brain function loss also associated.
Dilutors on the other hand work in an entirely different way, they work more like faucets regulating the flow or production of melanin (pigment granules) so that the final color is diluted. That being said, there are a few breeds and strains within breeds that are white \"because of\" the Bl blue gene. If you breed splashes to splashes you will \"technically\" get nothing but \"splashes\"......... but..... you can breed selectively towards a whiter and whiter flock. They wouldn\'t be any less white than whites made from the Dominant white gene, as both genes are considered to be \"incompletely dominant\". Which is why sometimes there a splotches of color \"bleeding through\" in white birds. It\'s not always caused by heterozygousity. As for the \"non-related\" genes that intensify or or negate the outward effects of another gene, otherwise called enhancers or in some cases negative trait causers, life doesn\'t take place in a vacuum. A perfect example of this resides in \"blue ameraucanas\", as no two blues look the same... some have narrow lacing, some have wide lacing and some are about right. Supporting genes have a LOT to do with the final product and cannot be ignored. I have at this time american pit fowl that posses the non-related genes powerful enough to completely cover up any traces of \"Bl\" blue. If a person didn\'t know what signs to look for, they would swear on a stack of bibles that the fowl were \"pitch black\". So......... don\'t judge a book by it\'s cover, as you have to meander through it\'s pages if you wish to understand the true meaning.
Which brings me to my last point...
In the past, poultry breeders who wanted a \"stay white\" breed of fowl quite honestly \"threw everything at the wall to see what stuck\", lol. In other words, they purposely bred dominant white, recessive white, blue, mottled, barring and anything else that stopped, slowed, diluted or \"got rid of\" color in order to make perfectly white birds that \"stayed that way\". Ironically, this is one of the main reasons why \"white fowl\" can be one of our greatest repositories for \"lost COLOR & PATTERN genes\" in the modern poultry world. If people only knew how great the potential of these fowl were, they\'d be grabbing up birds from old lines of \"white fowl\" and breeding them to colored fowl to see just \"what\" exactly they were hidding.
Regards,
Dan
