Colours of the Rainbow

COLOURS OF THE RAINBOW

SAMPLE LITTER

SIRE is a clear Champagne and DAM is Black and Tan. They produced 5 puppies of 5 apparent different colours. Many people would assume that many 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 were 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 so he must be [ee]. The dam does displays 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 must be [ee], the Dam must carry a recessive [e]. 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 the sire must also carry [ a^t ] as a hidden recessive. Sire is clear [ee] which can cover up all the A patterns, so what is he? His second A gene could be anything. We cannot know for certain, without seeing future litters he produces or clues from progeny produced by his offspring.

On the K locus - Dam is Black and Tan which is an expression of A so she must be[ kk]. Sire, is clear on the E locus [ee] 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 must carry one brindle gene [Br]. And seeing as one black and tan puppy was produced which has to be [kk], the sire must be [Br k ]

On the S locus - Sire is solid so must carry a dominant [S]. The Dam only has a touch of white ( toes on one paw) so she must also have a dominant [S]. One Broken coated puppy (well marked parti) was produced, which means that [sⁱ ] or or [s ^p ] must be 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^ce ] or [c^ch c^ch ]. The light pigment on the Dam ( tan points) were very golden at birth then lightened to creamy white as she matured. She may also be either [C c^ce ] or [c^ch c^ch ]. We cannot know for sure, but it is likely between these two that there is one [C], one [c^ch ] and one [c^e ].

Looking at possibilities from the A and E loci combinations

SIRE DAM possibilities for offspring

phenotype Champagne Black and Tan Brindle with mask Black and Tan with mask Clear

genotype [a^? a^t] [Kk] [ ee] [a^ta^t ] [ kk ] [E^m e] [a^? a^t ] [k^br k ] [E^m e ] [a^t a^t ] [kk] [E^m e ] [a^? a^t] [k^br k or kk ] [ee] OR [a^t a^t ] [k^br k or k k ] [ ee ]

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. Also potential for black and tan and tricolour (which results from the effect of the "S" gene on black and tan). What ever the sire is hiding on A may or may not have been expressed in this one litter.

1) 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 [at] recessives pairing up and there is one. As she matured, her tan lightened to creamy white which tells of activity on the C locus.

2) a brindle puppy was also possible and there is one of those too. He is coloured all over with no white at all. He does sport a black mask. His light coat is a caramel gold.

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.

Challenge - Can you guess what the genetic codes might be for the puppies as the A, C, E, K and S loci? What else can YOU tell about the parents or puppies genetic codes on other Loci?