A horse breeder would like to understand the genetics of the presence of the unique cremello
or smokey cream coat colour in her small herd of horses. She approaches you, a Genetics
student, and provides the following information about her herd of horses: When the breeder
set up her farm, she started with one mare and one stallion, which have since died of old
age. The mare was a chestnut colour and the stallion a cremello or smokey cream. The pair
produced four foals, first two fillies, then a colt and finally another filly. None of the foals born
had the stallion's smokey cream colour. When the mares reached breeding age, the breeder
purchased sperm from three unique stallions to inseminate her mares. The sperm to
inseminate the oldest of her three mares was from a stunning smokey cream-coloured
stallion. The donors for the other two mares were chestnut colour. The oldest mare, once
inseminated, produced a colt that was chestnut colour. The second eldest mare produced a
colt that was also chestnut in colour and the youngest mare produced a filly that was smokey
cream-coloured. The breeder also sold her chestnut stallion's sperm to a farmer who
inseminated a cremello mare, and the pairing produced a chestnut colt.
1.1 Construct a pedigree based on the information supplied by the breeder. Follow the
examples and details from the GNE3701 study material to prepare your pedigree. (12)
1.2 Analyse the pedigree and indicate the pattern of inheritance that is displayed.
Provide reasoning for excluding patterns of inheritance that have been discussed
in the GNE3701 study material. In your reasoning use evidence from the pedigree.
(13