Showdog.com Forum · Jack Russell Terrier
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| Author | Topic : Colour Genetics | |||
| MaxJax Basic User Posts : 362  |
I thought it might be nice to start researching colour in the hope that one day Jeff will get to the Jacks. Unfortunately I don't know much about colour genetics so I'm wondering if anyone with a bit more knowledge is willing to help out
 AKC Standard: White, white with black or tan markings, or a combination of these, tri-color. Colors are clear. As long as the terrier is predominantly white, moderate body markings are not to be faulted. Grizzle is acceptable and should not be confused with brindle. Disqualification: Brindle markings. The Australian National Kennel Council states that the tan markings can be from the lightest tan to the richest tan (chestnut). The following information I have found comes from this website: russellterrier.org/colorgenetics.html Although Jack Russells are mostly white, the white isn't the base color of the dog -- it is actually spotting. The colored patches on the terrier show the true base color of the dog. AA - black Aay - black carrying tan Aas - black carrying saddle markings Aat - black carrying tan-point ayay - tan ayas - tan carrying saddle markings ayat - tan carrying tan-point asas - saddle markings asat - saddle markings carrying tan-point atat - tan-point The dominant B gene produces the black color in terriers that are A or at and gives tan Jack Russells their black noses. Jack Russells that are bb have liver (or brown) noses and liver coloring where black should be, whether the terrier is A or at. BB black Bb black carrying liver bb liver (since Liver is unacceptable, and almost unheard of, in JRTs I think we should stick to BB - Jeff has said not to include the rare traits) The dominant C gene allows for full expression of color. Nearly all Jack Russells are homozygous (carry both genes for) C. The chinchilla gene (cch) dilutes color, like the d gene does. But it has its greatest effect on tan, producing a cream color. It is possible that "lemon" Jack Russells get their light color from the cch gene. The D series. Another of the simpler series, this one consists of two alleles, listed in order of dominance. D intense pigmentation d dilution of pigment I don't know whether we should use the 'd' gene or the 'cch' gene for the light tan. I think if we stick to simplicity we should use CC for all JRTs and then include the dilute genes DD - chestnut Dd - chestnut carrying lemon dd - lemon Although from personal experiences I would say that there is a standard tan colour (not as dark as chestnut and not as light as lemon) so perhaps we should go with: CCDD - chestnut CCDd - chestnut carrying tan CCdd - tan cchdd - lemon The E series. This series affects the expression of black pigment. Most Jacks are EE, with full expression of black pigment, but sometimes you'll see a brindle pop up. Brindle is the expression of black bars on a tan background and is unacceptable for Jack Russells. The recessive e gene, when homozygous (ee), restricts all black pigment (except in the nose) and produces color that can range from red to yellow. The markings contain no black hairs whatsoever, regardless of whether the terrier is A, ay or at. Although rare, there are ee Jack Russells and they are accepted by most registries because their noses are black and their color classification falls under the broad term "tan." Given the rarity of ee we should probably just go with EE, although I'm really not sure if the Grizzle effect would come from this gene. The G series. This series affects progressive graying. G allows graying g no graying Again, because of the rarity of graying in JRTs we should just go with all Jack Russells being gg. The M series is merle - there is no merle in Jack Russells so all are mm (no merle). The S series. This series allows white markings and its alleles are listed in decreasing order of dominance. S Solid. si Irish spotting (white on muzzle, forehead, chest, belly, feet) sp piebald spotting sw extreme-white piebald spotting Jack Russells get their white from the two piebald genes, sp and sw and the amount of white is largely dictated by modifiers. A dog with plus modifiers will have more color, while a dog with minus modifiers will have more white. The modifiers make it very difficult to tell whether a terrier is homozygous for one of the piebald alleles or has both. According to Willis and Little, it appears that some alleles in the S series may have incomplete dominance over others, and this likely has much to do with modifiers. Willis (Page 72) says "Generally sp will act as dominant to sw but much will depend upon the modifiers present as to the exact appearance of the spsw dogs. With many plus modifiers, they may seem to be more like spsp and with minus modifiers will show much more white." While modifiers help determine how much white is expressed, they do not appear to determine location of the pigmented areas. Willis, referencing other researchers, says that dogs appear to have standard "centers of pigmentation." He says on Page 71, "Burns and Fraser (1966) argue that the most important centers of pigmentation in the dog are on the ears and head and around the eyes such that these will be the last areas to become white. The next most important areas are at the root of the tail followed by patches on the ribs and finally by areas on the loin and lower part of the back." The amount of white can make it difficult to determine what the base color of the terrier is. For example, a dark tricolor terrier with just a few spots on his ear could appear to be black simply because the white areas of the coat cover all of the tan areas on the dog. We should probably just include a cross-section of spsw, spsp & swsw dogs. The T series. This series allows ticking. T allows ticking t no ticking Some Jack Russells have ticking. It is a dominant trait, and individuals pick up the small spots in the white areas of their coats as they mature. The color of the ticking is determined by the base color of the dog. Ticked Jack Russells are either TT or Tt, non-ticked Jack Russells are tt. The most pronounced example of ticking is found in the Dalmatian. Dals get their white from swsw and are TT. Because it's understood that JRTs are homozygous for certain traits that rarely appear we really only need to show the A, C, D, S & T series so all JRTs will have BB, EE (unless we include the Grizzle effect from this gene), gg & mm genes. Over the next couple of days I will go through and see if I can make a list of all colour combinations for both tan/white & tri-colour JRTs. I'd appreciate some input though as I'm only just learning about colour genetics and I may be incorrect on some points. We also need to come up with percentages for our starter dogs and while in my circle tan/white is much more common than tri-colour that may just be through the breedings of the few kennels I'm associated with. There does seem to be a fairly even distribution of tan & chestnut with lemon being less common, but again your input would be hugely appreciated. Sharon |
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| Fox Hollow Basic User Posts : 173 |
I applaud your research! Wonderful job! I only have the most basic understanding of genetics and haven't made the effort to dig into the thick of it. So I will be no help. But I can give my observations of dogs bred in my region from attending shows. One of the biggest changes I've seen over the last 8 years or so is the appearence of so many black/white's and tri's. Black being dominant is quickly gaining momentum. I see very few true tan/white's (and I look since they are my preference). I have tried to breed tan/white but after 5 litters totaling 15 pups, only 1 was tan/white, the majority were tri. My most recent litter was a black/white bitch to a tan/white stud and I got 3 black/white pups. I did expect the black dominance so no real surprise. But it does illustrate how overpowering that black gene is and why I see so many black/white dogs out there! Like I said, no real help but I think it's very interesting! |
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| Bounce Basic User Posts : 295 |
Your work looks great to me. Sorry to say I cant be of much help with this. I have zero experience with JRTs and I'm not very good with coat genetics. If you need some input I would recommend contacting Marchen Terriers. They have helped out tremendously in both my other breeds(Airedales and wire fox terriers). I could message other Jack breeders if you want and get them to take a look at what you have. Leigh |
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| MaxJax Basic User Posts : 362 |
Thanks guys. It's taken me a while to get back to this - real life is getting in the way  The little I know came from researching this so I guess we're all in the same boat. It's interesting to see another perspective on the high occurance of black & tri-colour, perhaps we should look at an even split of black/white, tan/white and tri and hope that we haven't bred the tans out altogether. Fox, from what I understand here about your own dogs there's a pretty good chance that your bitch is AA (carrying both black genes) and according to this research if the stud dog is a true tan/white then he must be ayay which means that if all your puppies are black then they must be Aay which means they're all carrying the tan gene. If you take these babies back to another tan/white you should get a bit luckier in producing a tan/white yourself. Of course there's every chance that they'll throw the A gene and not the ay but that comes down to luck. I'm about to breed my tan/white bitch to a tri-colour dog that has produced both tan/whites & tris so he's obviously an Aay, knowing my luck I'll get all tan/whites when I want a tri Hopefully sometime soon I'll be able to start producing a list of the possible mixes of genetics for each coat colour, I'll definitely get in touch with Marchen and see if she can take a look and we'll see if we can get the ball rolling. Sharon |
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| MaxJax Basic User Posts : 362 |
If we keep things simple we could just stick to the 3 AKC recognised colours - A Loci: A - black ay - tan as - saddle markings (tricolor) at - tan-point (tricolor) S Loci: sp - piebald spotting sw - extreme-white piebald spotting Black/White AAspsp AAspsw AAswsw Aayspsp Aayspsw Aayswsw Tan/White ayayspsp ayayspsw ayayswsw Tri-Color ayasspsp ayasspsw ayasswsw ayatspsp ayatspsw ayatswsw asasspsp asasspsw asasswsw asatspsp asatspsw asatswsw atatspsp atatspsw atatswsw I haven't included any grizzle, ticking or tan shadings since they're not in the actual colour classification. If we want to get technical and have chestnut/white, tan/white, lemon/white with/without grizzle, with/without ticking etc then a few more genes are required. Now for the percentages of our starter dogs - Depending on what we've been breeding, and how much inbreeding has gone on in earlier generations we could find we have totally bred out one (or even two) of the colours (like labs being all black now). Even so, what do you think if we start out with an even distribution of all 3 coats? Say, 33% black/white 33% tan/white 34% tri-color A general consensus would be great, so if Jeff sees our thread and everyone in agreement we might be next on the list. Leigh, if you could email all the JRT kennels that would be awesome. When we've got a few responses I'll email Jeff and get him to have a look. Like I mentioned before this is all new stuff to me so if anyone wants to add anything or tell me I'm wrong somewhere please speak up so we can fix it. Thanks, Sharon |
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| Bounce Basic User Posts : 295 |
I think this simplified version looks great. I also completely agree with the color percents you have proposed. I will send out a message and let others in the breed know about the post. Oh! I had also been meaning to ask you. Can JRTs be all white? Leigh |
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| Arrosa Premium Member Posts : 275  |
I wish I could offer an intelligent informed opinion, but I don't have one. LOL I'm fine with whatever the majority decides. |
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| Jumping Jacks of Glory Basic User Posts : 1,000+ |
Sounds good but, you may want to check out the CKC standard and the JRTCC (Jack Russell Terrier Club of Canada) just in case you missed any info. I'm not sure if there is any more info but just in case.  JJG |
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| Jakes Jacks Basic User Posts : 469 |
Hi There, I have PRT's in real life. Parson's are the AKC version of the Jack at this time, Russells may be recognized shortly. In PRT's the recognized colors are White, Tri (Black, brown and white),Black,Brown, Tan and Lemon. I believe the dominance should be 25% tri, 25% tan and white, 20% Black, 10% Brown and 5% lemon and 15% white. These percentages are based on what I've seen at the shows. The Black and White will dominate if the breeders choose to go that direction, so far it has not happened. There appears to be more Tris then anything but that is probably cyclical as this year I'm seeing more tan and whites at the shows. Since Jeff does not want to work with DQ's at this point, the color Blue and Brown Tri's should not be submitted even though they occur. |
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| JackBandit Basic User Posts : 3 |
I would love to help, but this is all way over my head. Im not a Jack Russel breeder lol im just a guy with a Jack Russel who started to play a game : ). I would love to learn more about the genetics and what not, so if anyone wants me to dig then im in. |
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| MaxJax Basic User Posts : 362 |
Thanks for your responses. I'm going to have to delve a little more into the genetics if we are to add all those colour classifications. I looked at the AKC breed standard for Parsons and all I saw was white, white with black or tan markings, or a combination of these, tri-color. In Australia anything brown (chestnut, tan, lemon) is all classed under tan but I think it'd be much more interesting to have a broader colour range so I'll work on it. White JRTs - I've seen a few white JRTs so I know they are around but I'm not sure how the genetics would work. From what I've learnt about the genetics the white is not a base colour, but actually a marking, which means white JRTs are not actually white but either black or tan with heavy markings that cover that base colour so I'm really not sure how to work that in with the genetics. Perhaps anything with 'swsw' can be classed as white. I think I can work out all the other colours with the C & D Locus. Jakes, when you refer to brown is that the darkest shade (what I've referred to previously as chestnut)? Sharon |
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| Fox Hollow Basic User Posts : 173 |
Just a quick note to say that I know many all white JRT's. I wouldn't say they are aboundant but they do make up a small but definate portion of the population. |
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| MaxJax Basic User Posts : 362 |
OK, here's the revised version. It's a little confusing to look at but I'd appreciate a second set of eyes. The white is what worries me the most but I basically added every combination to the 'swsw' gene since there really could be anything under those white markings. Technically the white dogs could have very small coloured markings but for the purpose of this game we'll call them all white. A Loci: A - black ay - tan as - saddle markings (tricolor) at - tan-point (tricolor) C Loci C - full expression of colour (black, brown & tan) cch - chinchilla (lemon) D Loci D - non dilute (black & brown) d - dilute (tan & lemon) S Loci: sp - piebald spotting sw - extreme-white piebald spotting (white) Black/White 20% AA-Aay-Aas-Aat|CC-Ccch|DD-Dd|spsp-spsw AACCDDspsp AACCDDspsw AACCDdspsp AACCDdspsw AACcchDDspsp AACcchDDspsw AACcchDdspsp AACcchDdspsw AayCCDDspsp AayCCDDspsw AayCCDdspsp AayCCDdspsw AayCcchDDspsp AayCcchDDspsw AayCcchDdspsp AayCcchDdspsw AasCCDDspsp AasCCDDspsw AasCCDdspsp AasCCDdspsw AasCcchDDspsp AasCcchDDspsw AasCcchDdspsp AasCcchDdspsw AatCCDDspsp AatCCDDspsw AatCCDdspsp AatCCDdspsw AatCcchDDspsp AatCcchDDspsw AatCcchDdspsp AatCcchDdspsw Tan/White 25% ayay-ayas-ayat|CC-Ccch|dd|spsp-spsw ayayCCddspsp ayayCCddspsw ayayCcchddspsp ayayCcchddspsw ayasCCddspsp ayasCCddspsw ayasCcchddspsp ayasCcchddspsw ayatCCddspsp ayatCCddspsw ayatCcchddspsp ayatCcchddspsw Tri-Color 25% asas-asat-atat-|CC-Ccch|DD-Dd|spsp-spsw asasCCDDspsp asasCCDDspsw asasCCDdspsp asasCCDdspsw asasCcchDDspsp asasCcchDDspsw asasCcchDdspsp asasCcchDdspsw asatCCDDspsp asatCCDDspsw asatCCDdspsp asatCCDdspsw asatCcchDDspsp asatCcchDDspsw asatCcchDdspsp asatCcchDdspsw atatCCDDspsp atatCCDDspsw atatCCDdspsp atatCCDdspsw atatCcchDDspsp atatCcchDDspsw atatCcchDdspsp atatCcchDdspsw White 15% AA-Aay-Aas-Aat-ayay-ayas-ayat-asas-asat-atat|CC-Ccch-cchcch|DD-Dd-dd|swsw AACCDDswsw AACCDdswsw AACCddswsw AACcchDDswsw AACcchDdswsw AACcchddswsw AAcchcchDDswsw AAcchcchDdswsw AAcchcchddswsw AayCCDDswsw AayCCDdswsw AayCCddswsw AayCcchDDswsw AayCcchDdswsw AayCcchddswsw AaycchcchDDswsw AaycchcchDdswsw Aaycchcchddswsw AasCCDDswsw AasCCDdswsw AasCCddswsw AasCcchDDswsw AasCcchDdswsw AasCcchddswsw AascchcchDDswsw AascchcchDdswsw Aascchcchddswsw AatCCDDswsw AatCCDdswsw AatCCddswsw AatCcchDDswsw AatCcchDdswsw AatCcchddswsw AatcchcchDDswsw AatcchcchDdswsw Aatcchcchddswsw ayayCCDDswsw ayayCCDdswsw ayayCCddswsw ayayCcchDDswsw ayayCcchDdswsw ayayCcchddswsw ayaycchcchDDswsw ayaycchcchDdswsw ayaycchcchddswsw ayasCCDDswsw ayasCCDdswsw ayasCCddswsw ayasCcchDDswsw ayasCcchDdswsw ayasCcchddswsw ayascchcchDDswsw ayascchcchDdswsw ayascchcchddswsw ayatCCDDswsw ayatCCDdswsw ayatCCddswsw ayatCcchDDswsw ayatCcchDdswsw ayatCcchddswsw ayatcchcchDDswsw ayatcchcchDdswsw ayatcchcchddswsw asasCCDDswsw asasCCDdswsw asasCCddswsw asasCcchDDswsw asasCcchDdswsw asasCcchddswsw asascchcchDDswsw asascchcchDdswsw asascchcchddswsw asatCCDDswsw asatCCDdswsw asatCCddswsw asatCcchDDswsw asatCcchDdswsw asatCcchddswsw asatcchcchDDswsw asatcchcchDdswsw asatcchcchddswsw atatCCDDswsw atatCCDdswsw atatCCddswsw atatCcchDDswsw atatCcchDdswsw atatCcchddswsw atatcchcchDDswsw atatcchcchDdswsw atatcchcchddswsw Brown/White 10% ayay-ayas-ayat|CC-Ccch|DD|spsp-spsw ayayCCDDspsp ayayCCDDspsw ayayCcchDDspsp ayasCcchDDspsw ayasCCDDspsp ayasCCDDspsw ayasCcchDDspsp ayatCcchDDspsw ayatCCDDspsp ayatCCDDspsw ayatCcchDDspsp ayatCcchDDspsw Lemon/White 5% ayay-ayas-ayat|cchcch|dd|spsp-spsw ayaycchcchddspsp ayaycchcchddspsw ayascchcchddspsp ayascchcchddspsw ayatcchcchddspsp ayatcchcchddspsw Let me know if there's any further additions or if you think I've missed something. Sharon |
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| noregrets2003 Basic User Posts : 500+ |
The brown that I've seen in pictures is what I consider a seal brown. The tan and whites can range in the AKC ring from a sorrel (horse color) to a dark chestnut. I've yet to see a lemon but it is described as a biegey color. Most tris brown out on their heads before a year old and if there is not body color can appear to be tan and white. The tri that keeps its black head are unusual in the PRT world. The whites are usually white with some ticking that will tell you the true color. There are a few whites that appear to be pure white as there is no ticking. These whites can dominate when bred to eachother. |
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| Bounce Basic User Posts : 295 |
Everything looks great to me! I really appreciate all the work you've done here MaxJax. I cant wait to get colors in this breed. I really don't see myself breeding for it, but i'm curious to know what color ratios Ive got in my kennel. Leigh Bounce |
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| MaxJax Basic User Posts : 362 |
Exciting News!! I just read in the main colour genetics thread that we are able to incorporate coat type as well as colour! quoteIt would have to be incorporated into each colour gene so we would have a total of 18 classifications - ie. 3 coat types & 6 colours. I'm looking into the gene codes now, does anyone want to have a go at the percentages for each colour/coat? LOL. Sharon |
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| Rainbeaur6 Basic User Posts : 169 |
A quick comment. In the PRT show rings smooths are rare, however they do exist. I would say breaking down the percentages there are 25% smooth, 50% broken and 25% rough, spread evenly across all colors. |
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| Jumping Jacks of Glory Basic User Posts : 1,000+ |
quoteI had mentioned this to Jeff before but he said he was not sure at the time. Looks like he liked it and there was probably either a lot of response or many people with the same idea. I like this much better it will be better with our JRT's since colour on JRT's is really just markings and I know that here in Canada and I am pretty sure in the U.S. it is the same that the body of the JRT is suppose to be white with markings on the base of the tail and on the head. But their is aloud only a certain size that a marking on the body can be. JJG |
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| Jumping Jacks of Glory Basic User Posts : 1,000+ |
How would I go about finding the percentages? Send me a message JJG |
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| noregrets2003 Basic User Posts : 500+ |
In the US all body markings are allowed. The head and tail markings are what you usually see in the show ring however color can happen. The wording is the dog needs to be predominantly white 51%. Looking forward to seeing the jacks with color and hopefully coat type. |
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| Jumping Jacks of Glory Basic User Posts : 1,000+ |
quoteYeah most dogs in the ring have almost all white or literaly all white bodies. JJG |
7/23/2008 4:32:11 PM|
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