![\"\"](\"https:\/\/oceanecology.ca\/wp\/wp-content\/uploads\/2019\/04\/border-collie-parents.jpg\")
<\/a><\/p>\nHere is some more information:<\/p>\n
Male:<\/strong><\/em><\/p>\n Mahogany sable with amber eyes; parents were both black white tri-colored.<\/p>\n Female:<\/strong><\/em><\/p>\n Black white tri-colored with wall eyes – one blue and one marble; nose and front legs have a small amount of ticking; parents were both black white tri-colored.<\/p>\n Pups:<\/strong><\/em><\/p>\n Three of the pups are black white tri-colored.\u00a0 All three have black noses.\u00a0 One of these pups has wall eyes (one blue and one amber) and limited ticking.\u00a0 The other two have brown eyes and no ticking.<\/p>\n Four of the pups are brown and white.\u00a0 All of them have noses which look to be either black\/pink or brown\/pink.\u00a0 One of the four is a chocolate white tri-color with limited ticking and amber eyes.\u00a0\u00a0 The other three are much lighter in color, show a bit of black tipping on their fur, and are likely sables.\u00a0 One of these sables has light patches around the eyes.\u00a0 All three of the sables have wall eyes (one blue and one amber).<\/p>\n What is the genetic explanation for the colors of both parents and pups?<\/strong><\/em><\/p>\n Let’s take a quick look at the genes that affect coat color in border collies.\u00a0 These are:<\/p>\n A locus (agouti):\u00a0<\/p>\n \nAy<\/sup> – sable \nB locus (black\/chocolate):<\/p>\n \nB – black D locus (dilution):<\/p>\n \nD – no dilution \nE locus (extension):<\/p>\n \nE – eumelanin present \nH locus (harlequin merle modifier):<\/p>\n \nH – harlequin K locus (dominant black):<\/p>\n \nK – solid black \nM locus (merle):<\/p>\n \nM – merle \nS locus (spotting):<\/p>\n \nS – no white spotting T locus (ticking):<\/p>\n \nT – ticking Tw locus (tweed merle modifier):<\/p>\n Tw – tweed A locus alleles will only be expressed when a dog does not have a dominant black (K) gene.\u00a0 S locus alleles (white spotting) appear on top of anything else a dog has and are not masked.\u00a0 D and B locus alleles will override all alleles for black (dominant or recessive) and change all eumelanin on the dog.\u00a0 E locus alleles are not overriden by anything except the S (white spotting) locus, so recessive red will be expressed even on a dominant black dog.\u00a0 The H and Tw locii will only be expressed on a dog with the merle allele (M locus) and the T locus will only be expressed on a dog with white spotting (S locus).<\/p>\n Wow!\u00a0 I don’t think I ever handed out a problem that complex to my students!\u00a0 If you find that this is already blowing your mind, a really good site to check out is Dog Coat Colour Genetics<\/a>, which has lots of definitions, explanations, and good pictures.<\/p>\n In researching this topic myself, I found a wonderful infographic called All Border Collie Colors<\/a> made by Suzanne Van Der Kraan.\u00a0 I have taken the liberty of modifying this graphic by adding the genotypes for each color, which helped me wrap my head around the complex interactions between ten gene locii.<\/p>\n\n A couple of great web pages for images of actual collies with particular coat colors are Collie Colors<\/a> and Looks and Diversity in the Border Collie<\/a>.<\/p>\n OK, so there’s all the information necessary to solve the puzzle.\u00a0 Let’s look at each piece in turn.<\/p>\n Male:<\/strong><\/em><\/p>\n The male is a very nice mahogany sable [(kk)(Ay<\/sup>at<\/sup>)], like this rough collie:<\/p>\n What’s interesting here is that the male’s parents were both tri-colored [(kk)(at<\/sup>at<\/sup>)].\u00a0 Sable is dominant to tri-color, and you can’t generate a sable by crossing two pure tri-colors.\u00a0 So, something else must be happening here. My guess is that one of the male’s parents was actually a seal.\u00a0 Seals were often classified as tri-colors, but they have a different genotype [(K-)(Ay<\/sup>-)].\u00a0 Here is an example of a border collie with a seal coat:<\/p>\n Note that the coat is very similar to a black white tri-color, such as the the one shown below, which has quite limited amounts of brown.<\/p>\n Another clue to the male’s genotype is that there is at least one chocolate puppy in the litter.\u00a0 To get chocolate, you need to have (bb).\u00a0 Since neither of the parents are chocolate, they must each be carrying a single recessive chocolate allele, and the chocolate pup received a recessive allele from each parent.<\/p>\n My guess at the cross that produced the male is:<\/p>\n [(kk)(at<\/sup>at<\/sup>)(Bb)(D-)(mm)(si<\/sup>si<\/sup>)] \u00a0 x\u00a0\u00a0 [(K-)(AY<\/sup>-)(B-)(D-)(mm)(si<\/sup>si<\/sup>)]<\/p>\n black white tri-color\u00a0\u00a0 x\u00a0\u00a0 seal<\/p>\n and the male’s genotype is:<\/p>\n [(kk)(AY<\/sup>at<\/sup>)(Bb)(D-)(mm)(si<\/sup>si<\/sup>)]<\/p>\n Female:<\/em><\/strong><\/p>\n On first glance, the female seems to be a fairly typical black white tri-color.\u00a0 However, two things should be noted: (1) she has light ticking on her nose and forelegs, so she must have a (T-) genotype; and (2) she has blue eyes.<\/p>\n There are three ways in which border collies can have blue eyes:<\/p>\n A clue to the blue eye mystery is the color of several of the pups’ noses.\u00a0 They appear to have some pink, mixed with either brown or black.\u00a0 This is likely a mosaic pattern, which indicates that they may have the merle gene (M-).\u00a0 However, except for the blue eyes, the female shows little indication of being a merle.\u00a0 My guess is that she is a cryptic merle (Mc<\/sup>-), like this Australian shepherd:<\/p>\n My guess at the cross that produced the female is:<\/p>\n [(kk)(at<\/sup>at<\/sup>)(Bb)(D-)(Mc<\/sup>-)(T-)(si<\/sup>si<\/sup>)] \u00a0 x\u00a0\u00a0 [(kk)(at<\/sup>at<\/sup>)(Bb)(D-)(mm)(tt)(si<\/sup>si<\/sup>)]<\/p>\n black white tri-color cryptic merle with ticking \u00a0 x\u00a0\u00a0 black white tri-color without ticking<\/p>\n Note that both parents could be cryptic merles and ticked, or that one parent could be ticked and one could be a cryptic merle.\u00a0 Also, one parent could be (BB).<\/p>\n In any case, I’m guessing that the female’s genotype is:<\/p>\n [(kk)(at<\/sup>at<\/sup>)(Bb)(D-)(Mc<\/sup>m)(Tt)(si<\/sup>si<\/sup>)]<\/p>\n Pups:<\/strong><\/em><\/p>\n Based on the above rationalization, the pups are produced by the cross:<\/p>\n [(kk)(AY<\/sup>at<\/sup>)(Bb)(D-)(mm)(tt)(si<\/sup>si<\/sup>)]\u00a0\u00a0 x\u00a0\u00a0 [(kk)(at<\/sup>at<\/sup>)(Bb)(D-)(Mc<\/sup>m)(Tt)(si<\/sup>si<\/sup>)]<\/p>\n mahogany sable\u00a0\u00a0 x\u00a0 black white tri-colored cryptic merle with ticking<\/p>\n My guesses at their genotypes are:<\/p>\n So there you have it!\u00a0 Other guesses welcome!<\/p>\n","protected":false},"excerpt":{"rendered":"
\naw<\/sup> – agouti\/wolf grey
\nat<\/sup> – tri-color or tan points
\nasa<\/sup> – saddle
\na – recessive black<\/p>\n
\nb\u00a0 – chocolate<\/p>\n
\nd – dilution of eumelanin to blue or lilac<\/p>\n
\ne – eumelanin suppressed to produce recessive red<\/p>\n
\nh – non-harlequin<\/p>\n
\nkbr<\/sup> – brindle
\nk – non-solid black<\/p>\n
\nMc<\/sup> – cryptic merle
\nMa<\/sup> – abnormal merle (maltese blue)
\nm – non-merle<\/p>\n
\nsp<\/sup> – piebald
\nsw<\/sup> – extreme white
\nsi<\/sup> – irish spotting (may not be on S locus)<\/p>\n
\nt – no ticking<\/p>\n
\ntw – non-tweed<\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n\n
\n
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<\/a><\/p>\n\n
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\nBlack white tri-colored cryptic merle with ticking (one pup like the female)<\/li>\n
\nBlack white tricolored (two pups)<\/li>\n
\nChocolate white tri-colored with ticking (one pup)
\n<\/a>
\nMahogany sable or chocolate sable cryptic merle (three pups)
\n<\/a>