Okay, so let's go back to the beginning. One of the rabbit color genes is called 'E', short for extension, and it affects how the color is extended down the hairshaft. There are five possibilities on this gene, each called an allele. Each allele in this case is incompletely dominant. There is a descending order of dominance, but a recessive allele can work in the background to change up the color some. Here they are: (By the way, capital letters denote dominant traits, lower case letters are recessive traits. Generally the stuff in the parenthesis are subscript or superscript letters, but lacking that capability here, I'm just using parenthesis.)
- E(D) Dominant black--this one is quite rare, only found in few breeds. It takes regular agouti patterning like castor, and turns it all black, gets rid of all the agouti markings. Not an issue in most breeds.
- E(S) Steel--dominant over normal color, this one extends the base color up the hairshaft, pushing the center agouti band clear out to the end of the hairshaft, leaving a gold tipping (or silver tipping on a chinchilla). Steel usually only fully presents itself in agouti rabbits, since it's moving an agouti pattern around to make the tipping.
- E Normal Extension--this is your normal patterning. In agouti rabbits, you get your normal undercolor, center fawn band, and outer color with normal tipping--everything in it's proper place, or properly extended, which is why this is called the Extension gene.
- e(j) Harlequin--this one takes the normal agouti patterning, and instead of splitting it up on one hairshaft, splits it up in patches on the skin, either in patterned bands/bars, intermixed hairs called brindle (roan in horses), or simply splotches. So, a genetic chocolate agouti that should have chocolate and fawn on the hairshaft would become a chocolate/fawn harlequin, with splotches of those two colors in some definite pattern, some random mix, or simply brindled.
- ee Fawn--this last one on the totem pole is what we call the fawn colors--yellow based pheomelanin golden, orange or red tones. The center fawn agouti band gets pushed to the outside, leaving only the fawn (and often a white base color). For agouti rabbits, this forms fawn/cream/orange/red colors. For non-agouti rabbits, the main body color is still fawn, but the normal genetic color still shows up on the extremities, forming tortoiseshells.
A harlequinized color is what happens when a rabbit with an 'E' allele higher than harlequin (usually just plain normal 'E') has a harlequin e(j) recessive. Because this series is incompletely dominant, the harlequin messes with the color. It can cause dark ticking, or harlequin patterning where the agouti markings should be, etc. A/E Gene Combinations has a great chart to show how the colors interact.
If a rabbit ends up with two harlequin alleles, or a harlequin and a fawn, they will show harlequin traits--like the tris, which are broken harlequin. If your buck has a recessive harlequin, and so does the doe--or if one of them carries recessive harlequin, and the other recessive fawn (either tortoiseshell or fawn agouti), either way you could end up with harlequin line kits. If you mate the tri kits back to a solid harlequin or fawn carrier, you could end up with harlequin kits.
