by Eric Stewart

            No, don’t shy away just yet....genetics isn’t that difficult to understand.  In fact, genetics is much more interesting and applicable than that old prune of a teacher in high school perhaps made it sound.  I’ve had quite a number of breeders ask me a multitude of questions in the past couple months with regard to color genetics. I believe the easiest way to explain the principles is to teach them.  These color genetics will be geared more toward our lops but are applicable to all breeds of rabbits.  If you’ve heard that different breeds have different genetics, you’ve heard wrong....we all have the same species of rabbit here folks; occasionally varying names for the same color but not genes.

            First, let’s start with the basics: Genes are what determine specific characteristics of all organisms.  All mammals receive a set of genes from each parent (under normal circumstances *grin*) - that all makes sense, right?  We have a term to refer to specific genes.  We call these genes alleles,  ie. “I have brown eyes, therefore I must have at least one allele for brown eyes” or “I am going bald, therefore I must have the alleles for baldness (thanks alot mom and dad, I’d rather inherit $$.)”  Combinations of alleles make up our traits, the same applies to rabbit colors.  Some alleles are dominant and some recessive.   This means that although both alleles may be present:

·        The  dominant allele’s trait is visually apparent over a recessive  (you can SEE it.)

·        However, the recessive’s trait  are not visually apparent over a dominant’s trait (it is there but you can’t SEE it.) 

·        Dominant alleles are represented by a capital letter, recessives are represented by a lower case letter.

            There are 5 basic alleles that are considered or discussed at length when determining a rabbit’s color.  The A allele determines the number of colors on the hairshaft (agouti, tan pattern or self.)  B determines the basic color (black or chocolate variations.)  C determines the presence or absence of yellow pigment (full yellow/orange color, chin genes, pointed white, or REW.)  D dictates the density (dense or dilute.)  The E determines the amount of expression of the basic color or underpigments on the hairshaft (steel, full extension, harlequin and non extension.)  These alleles interact to give us the colors we have at present.  Each allele has a minimum of 2 variations (variants) in an order of dominance.  DON’T GET FREAKED OUT....this will all make sense very soon...........

A- Is for agouti, it is referred to as the agouti gene.  This is the dominant wild type; an ‘A’ is dominant over ‘at’ (tan pattern) and ‘at’ is dominant over ‘a’ self.  We will not cover the Tan pattern as they are not recognized in the lop breeds.  Agouti’s have a banded hairshaft as well as the typical nostril, collar, triangle, belly, tail, jowls eye circles and ear lacing markings.  Self colored animals do not have any of these markings nor do they have a banded hairshaft....They go in descending order, easy to remember, eh?

Now for a couple examples, ‘aa’=self, ‘AA’=agouti,  ‘Aa’=agouti. Look in your standard of perfection page 152 to find examples of agouti and self colors recognized by the ARBA for lops.

B- O.K., this is an easy  one folks; you can actually think of it as the brown allele if you like...it determines whether or not a rabbit’s base color is black (black or blue) OR brown (chocolate or lilac.) B is most common in the lops and codes for a normal base, b codes for brown. Pretty simple; BB=normal, Bb=normal, bb=chocolate or lilac.

C- This is perhaps the most complex allele of them all, don’t get frustrated though....break it down and its easy.

·        ‘C’ is the premier dominant color (wild type), it causes all of the normal underpigments to be expressed.  It is what makes a tort orange, the banding on chestnut agoutis and opals as well as ticking on gold tipped steels to be orange or fawn.

·        ‘cchd’ is the next most dominant and is responsible for stripping the coat of most of it’s yellow underpigments and only leaving silver/white behind; its what makes a tort turn into a sable point, a chestnut into a chinchilla, opal to squirrel, gold tipped steel to silver tipped steel, etc.

·        ‘cchl’ follows on the proceedings’ heels, the two are very closely related but create slightly different effects.  ‘cchl’ takes the remaining yellow pigments out of  the coat thus leaving a sepia/brownish tinge to the surface pigments instead of black.  This is the allele that creates siamese sables, sable agoutis (notoriously mistaken for chocolate chins-THERE IS A DIFFERENCE), smoked pearls, sable steels, etc.

·        ‘c’ is a very cut and dried allele. If there are ‘cc’ then the animal is automatically a REW, it negates the rest of the animals color genome and will definitely be REW. All of the other C alleles are dominant over ‘c’ but when two of these little guys finally get together-they rule the roost.

D- Is for dense/dilute.  The normal wild type is dense ‘D’. This codes for the dominant colors ie. black, chestnut, chocolate, tort, etc. ‘d’ codes for dilute (a.k.a. the ‘blue version’) version of each  dense color ie. blue, opal, lilac, blue tort, fawn, squirrel, etc.  ‘DD’=dense, ‘Dd’=dense, ‘dd’=dilute.

E- Is the extension allele.  O.K., I have got to admit that the ‘E’ alleles can be almost as complicated as the ‘C’ series....bear with me. The wild type is E.  Each time I mention wild type, think of Peter Cottontail-he was a chestnut agouti.  This allows for normal expression of all pigments on the hairshaft.  However, this is the confusing part, it is not the dominant allele.  

·        The dominant allele of the extension series is the ES allele which codes for steel (we all know that steels are my ultimate favorites.)  The steel allele ‘ES’ intensifies the surface pigments so that it basically obscures the ring pattern of the ‘E’ gene.  This is why a steel’s coat lacks the ring of an agouti, has a grayish belly and retains it’s ticking.  This is the trick however, a rabbit with two steel alleles (ESES) appears black even though it is a steel because of the ultra-intensifying effect of ‘ESES’.   A rabbit with at least one A and only one ‘ES’ will have the proper steel ticking, thus good steel color.  A rabbit that is a self, ‘aa’, and only one ‘ES’may show slight steel coloration usually around the nape and lower flanks/chest but will be self colored for the most part because self rabbits lack the necessary agouti ticking. O.K., I’ll admit that steels can be pretty complicated, breeding them correctly, that is.......

·        The ‘E’ gene follows the ‘ES’ in dominance and as stated above codes for normal expression of the pigments on the hairshaft.

·        The next in order of dominance is the harlequin gene ‘ej.’  I am discussing this allele as it is a part of the recognized lop genome.  It is perhaps the most integral part of creating the tri-color pattern.  Any tri-colored rabbit is basically a broken harlequin.  I will stop the discussion here as introducing this allele into a line can be like playing with fire and I would definitely not suggest it:  Unless one has a firm grasp on this variety, I would strongly suggest avoiding it (note that I repeated  that statement.)

·        The most recessive gene is the ‘e’ allele which causes the under pigments to basically overtake the hairshaft.  This is what will change a black to a tort, chestnut agouti to an orange, chin to a frosted and a sable/siamese sable to a sable point.  This goes even further to show the relationship of the alleles, note the rabbits with ‘C’s express the orange (under pigment) and show very little ticking/shading (surface pigment) and the ones with the ‘cchl or cchd’ express white (under pigment) with only slight ticking/shading (surface pigment.)

EE-normal, Ee-normal, ESES-normal, ESE-steel, Ese-steel, Esej-steel, Eej-normal, ejej-harlequin, eje- harlequin, ee- non extension.

Es-Is for English Spot, also known as the broken allele.  Es is dominant over all colors, that is why you must have a broken to get a broken (we’ve had fights over this but I challenge you for documented proof of otherwise) unless one of the parents was a REW which could be a broken but not visibly (remember, although cc is a recessive gene, when present will mask all other genetic combinations.) EsEs-charlie or poorly marked broken, Eses-broken, eses-solid.

Now that you have the background on the general genetics of the different alleles, you should have an idea as to the role of each allele.  A-bands or lack thereof on the hairshaft/agouti-tan markings, B-black vs. brown, C-presence of orange vs. white pigment, D-dense vs. dilute, E-extension of color on the hairshaft, Es-the broken gene (pretty obvious.)  This gives you the power and authority to predict and plan your color breedings; you have the basic knowledge to be a lop color geneticist. Cool, huh?

“O.K., now I know all the stupid letters-that means nothing to me.  My pedigrees certainly do not have all of those letters stamped on each animal; this was a waste of my time.”  Actually, each animal DOES have those letters stamped on it.....it’s coat color tells you the ‘letters.’  When you look at a rabbit and see the variety to which it belongs; that is its phenotype (what you see.)  All the funky ‘letters’ represent the genotype (the alleles/DNA that God put inside the cells that dictate what it may pass on to its offspring.)  You generally cannot see recessive alleles by visually looking at the rabbit.  A rabbit’s phenotype is determined by its genotype.  What you see is determined by the rabbit’s genetic composition.  Let’s say your herd buck is a chestnut agouti named....ummm, let’s say ‘Bubba.’  You know that he has a banded hairshaft and agouti/tan markings so he must have an ‘A’.  He is black on top and not chocolate so he must have a ‘B’.   He shows orange pigment in his ring/markings so he must have a ‘C’ .  He is black on top and not blue so he must have a ‘D’.  He has even distribution of coat extension (he is of the normal wild type,) therefore he must have an ‘E.’  By merely looking at Bubba you have determined that his genotype is A_B_C_D_E_. Those little lines after the letters are spaces to add what his other alleles may be, you cannot determine those alleles by looking at him but you may fill in some blanks by looking at his pedigree. Lets say that his father was a Black Tort and his mother a Squirrel; determine their genotypes by looking at their phenotypes:

·        Daddy was a tort; tort is a self color-’aa’,  wasn’t a chocolate tort so he was ‘B_’, was orange so ‘C’, was not a dilute so ‘D_’, lacked the surface pigments so excessive orange was shown ‘ee.’  aaB_C_D_ee

·        Mommy was a squirrel; squirrel has a banded hairshaft and agouti/tan markings so ’A_’,  she is not chocolate/lilac on top so ‘B_’, she has pearl white ring pattern/markings instead of orange so ‘cchd_’,  blue surface color means she was dilute and not dense so ‘dd’ (remember, with recessive genes, it takes 2 to make it happen,) and she displayed the even distribution of surface pigments of a normal wild typed animal so ‘E_.’

       A_B_cchd_ddE_

Let’s look at Bubba again; we know his patchy genotype from merely looking at him, now let us add a few more pieces... Daddy was a self ‘aa’ therefore he could only pass on an ‘a’ to his son.  Remember each parent passes on a set of genes to the offspring; “Can’t pass on whatcha ain’t got.” Daddy also passed on an ‘e’ to Bubba so we now know that Bubba is AaB_C_D_Ee.  Pretty easy eh?  Mommy was a squirrel so you know that he must have gotten his ‘A’ from her and his ‘E’ from her; however, she was recessive in two areas, she passed on a ‘d’ and either a ‘cchd’ , ‘cchl’, or ‘c’ {its hard to tell which of the three without test breeding her.)  Therefore  daddy threw in his ‘C’ and ‘D’ to make Bubba a bouncy baby chestnut agouti AaB_C_DdEe.  Note that spaces are left on the B and C alleles as we are not entirely sure what is there....that would take additional investigative work.  You can continue to do this as far back on the pedigree as possible.

You can peruse your pedigrees, assigning what genotypes are present to the best of your assertation:  This will aid you in determining what you may get with regard to color when you breed particular animals together.  You would do this by creating a Punet square with the parental genotypes on the axis’.   For example:  Dad-Black Gold Tipped Steel  aaBBC(cchd)DDESe

                                         Mom-Opal AaBBCcddEe

·              Take each parents genotype and split it up so that you put together                                               every  possible combination.  Since each parent only passes on one set of                             alleles to the offspring, each parent can pass on 5 alleles to the young. When the two         sets combine, making a pair, your end result is attained.

               aBCDES                 aB(cchd)DES         aBCDe             aB(cchd)De

ABCdE  AaBBCCDdESE   AaBBC(cchd)DdESE  AaBBCCDdEe AaBBC(cchd)DdEe 

ABcdE   AaBBCcDdESE    AaBB(cchd)cDdESE   AaBBCcDdEe  AaBB(cchd)cDdEe

ABCde   AaBBCCDdESe   AaBBC(cchd)DdESe   AaBBCCDdee  AaBBC(cchd)Ddee

ABcde    AaBBCcDdESe    AaBB(cchd)cDdESe    AaBBCcDdee    AaBB(cchd)cDdee

aBCdE   aaBBCCDdESE  aaBBC(cchd)DdESE    aaBBCCDdEe   aaBBC(cchd)DdEe

aBcdE     aaBBCcDdESE    aaBB(cchd)cDdESE     aaBBCcDdEe   aaBB(cchd)cDdEe

aBCde    aaBBCCDdESe    aaBBC(cchd)DdESe    aaBBCCDdee   aaBBC(cchd)Ddee

aBcde     aaBBCcDdESe     aaBB(cchd)cDdESe     aaBBCcDdee     aaBB(cchd)cDdee

            O.K., did you see how I merely took all of the possible variations to each parents genotype and put them along two axis’ (remember, each parent passes on one set of genes to the offspring)?  Dad is on the horizontal axis and mom on the vertical axis.  Dad has 4 possible combinations and mom has a whopping 8.... 4X8=32 possible genotypes they could produce: That is genotypes produced, not phenotypes produced.  You can see that there are 11 possible colors that can be produced from such a breeding, as you wont visually see all of the variations of the genotypes (when you ‘look’ at a lop, a ‘CC’, ‘Cc’ and a ‘Ccch’ all look the same.) 

            A breeding of the above animals could produce Black gold tipped steel, poorly ticked black gold tipped steel, silver tipped steel, poorly ticked silver tipped steel, chestnut agouti, orange, black, tort, chin, frosted, seal, and sable point.   As you look over the Punet square you will notice the majority of the ‘hits’ are steel or some steel variation with the slimmest chances being the more recessive colors ie. chin, frosted, seal and sable point.

Not that difficult is it?  If you have trouble understanding it all, read over it again, make notes, put things into your own words, look back at the beginning of the article to review concepts....you’ll get the hang of it!

Here are some of the more common lop colors.

·        Chestnut Agouti:A_B_C_D_E_

·        Opal:A_B_C_ddE_

·        Chinchilla:A_B_cchd_D_E_

·        Sable Agouti:A_B_cchl_D_E_

·        Squirrel:A_B_cchd_ddE_

·        Frosted:A_B_cchd_D_ee (these are currently INCORRECTLY listed as shaded animals, something to think about for the next standard.)

·        Blue Frosted:A_B_cchd_ddee

·        Orange:A_B_C_D_ee  (these are generally and erroneously called ‘fawn’ by english lop breeders and have been for years.)

·        Fawn:A_B_C_ddee  (these are generally referred to as ‘lynx’, perhaps the most erroneous of them all as even the color description in the standard of perfection states that they should have brown eyes....it’s a dilute, it should state that they must have blue/gray eyes. A true lynx is orange shot lilac....not blue.)

·        Black:aaB_C_D_E_

·        Blue:aaB_C_ddE_

·        Chocolate:aabbC_D_E_

·        Lilac:aabbC_ddE_

·        BEW:____   ____vv (If ‘cc’ present, it makes the BEW a REW.)

·        REW:____cc____

·        Black Tort:aaB_C_D_ee

·        Blue Tort:aaB_C_ddee

·        Sable Point:aaB_cchd or cchl_D_ee

·        Smoked Pearl:aaB_cchd or cchl_ddee

·        Black Gold Tipped Steel:A_B_C_D_ES_

·        Poorly Ticked Black Gold Tipped Steel:aaB_C_D_ES_

(Each steel variant has the same self version.                                                    I wont repeat the poorly ticked example as it is repetitous.)

·        Black Silver Tipped Steel:A_B_cchd_D_ES_

·        Blue Gold Tipped Steel:A_B_C_ddES_

It is important to note that these are not all the colors recognized in the lop standard; merely more common ones.  Genotypes of other varieties may be extrapolated by using this article and the principles of Mendelian genetics.  Also realize that just because you bred two animals together that ‘should’ produce a particular color, unless the odds are high you may not see it unless you repeat the breeding several times.

I’ve done my best to keep this an introduction to lop genetics, if the interest is clearly present I will provide a more in-depth article the next time.   Please contact me with specific questions and we’ll address the areas of difficulty.  Excellent resources regarding rabbit color genetics are available at the Library of Congress and Bobby Schott from GA is by far the foremost expert in the fancy.  Good luck and don’t give up!

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