QUIZ # 1 - answer

Litter study

Many people would assume that innumerable possibilities for coloured puppies of all sorts exist with such a pair of dark and light. Looking at the genetics tells us that the possibilities are quite a bit more limited than one might expect. How is this possible? From this litter, we can extrapolate the following about the parents in regards to the interactions of the A, E and K genes along with the input of the C and S.

The E locus : Sire is clear and displays no dark pigmented coat whatsoever so he must be [ ee ]. The dam does display dark pigmented coat so she must have at least one [ E ]. A black masked puppy was in the litter, so we can assume her dominant is [ E ^m ]. Seeing as clear puppies were also produced, which can only be [ e e ], the Dam must carry a recessive [e]. So now we know that Sire is [e e] and Dam [ E^m e ]

On the A locus : Dam is Black and Tan, so can only be [ a ^t a ^t ]. Seeing as a black & tan puppy was produced, which can also only be [ a ^t a ^t ], this means that the sire must also carry [ a ^t ] as a hidden recessive. Sire is clear [ e e ]. Remember that this can cover up all the A patterns. So what is he? His second A gene could be anything. We cannot know for certain, although there may be more clues to be found by examining his litters produced in the past, seeing future litters he produces, or gathering clues from progeny produced by his offspring.

On the K locus : Dam is Black and Tan which is an expression of A so she is likely [ k k ]. Sire, is clear on the E locus [ e e ] which produces no dark pigment at all and can hide any and all of the K alleles. Seeing as a Brindle puppy was produced, he may carry one brindle gene [ k ^br ]. And seeing as one black and tan puppy was produced which is likely [ k k ], this leads us to believe that the sire could be [ k ^br k ].

On the S locus : Sire appears solid coloured so must carry a dominant [ S ]. The Dam only has a small amount of white on one paw so she also likely has a dominant [ S ]. One broken coated puppy (well-marked particolour) was produced, which means that [ s ⁱ ] or or [ s ^p ] is most likely present in both parents. Both dam and sire are likely [ S s ⁱ ] or [ S s ^p ].

On the C locus: Sire is clear. He was born a middle range champagne colour, probably [ C c ^e ] or [ c ^ch c ^ch ]. The tan points of the dam were golden at birth then lightened to creamy white as she matured. She may be either [ c ^ch c ^ch ] or [ c ^ch c ^e ]. We cannot know for sure, but looking at the puppies produced with clear colours from gold to cream, it is likely that between the parents that we would find [ C ], one [ c ^ch ] and one [ c ^e ] to create the assorted combinations.

With this information, we can see that this breeding had the potential to produce brindle and clear puppies in solid or broken coats. Light portions of the coat could vary from gold to cream. There is also potential for black and tan and tricolour (which results from the effect of the "S" gene on black and tan). Whatever the sire is hiding on A as his second possibility may or may not have been expressed in this one litter. One possibility (still a guess) is Sable with mask.

Black and Tan: From the possibilities determined above for the sire and dam we can see that a black and tan puppy was possible in the eventuality of the two [ a ^t] recessives pairing up. As the puppy matured, the tan points lightened to creamy white which tells of activity on the C locus.

Brindle: A brindle puppy was also possible. He is coloured all over with no white at all. He sports a black mask. His light coat is a caramel gold.

Clear: Clear puppies were also on the potential list. There are a few different genotypes on the "A" locus possible for the three clear puppies that were born. Remember [ee] can hide any and all of the A and K patterns. Right now, there is no way to tell which of these A and K gene code possibilities is carried by these three puppies. Additional clues could be found from progeny produced in the future if they are bred. Puppy # 3 is a Gold particolour, with the gold very well distributed through the head and back. # 4 is a clear champagne colour while # 5 is a clear cream colour.

Unknown: The genotype for our unknown possibility is [a^?a^t] [E^me] [kk]. The [E^me] combination tells us it will have a dark mask. The [kk] combination tells us that A will be expressed. The a? could be any A pattern. A^y, a^w, a^st or a^t.

Like the challenge and want some more? Try to guess what the genetic codes might be for the puppies at the A, C, E, K and S loci. What else can you tell about the parents or puppies genetic codes on other Loci?