Dihybrid cross involving dog coat color
Labrador retrievers may be black, brown, or golden in color.
While each color may breed true, many different outcomes occur if numerous
litters are examined from a variety of matings, where the parents are not
necessarily true-breeding. The results below show some of the possibilities.
Propose a mode of inheritance that consistent with these data, and indicate the
corresponding genotypes of parents in each mating. Indicate as well the
genotypes of the dogs that breed true for each color.
A: black x brown = all black
B: black x brown = ½ black, ½ brown
C: black x brown = ¾ black, ¼ golden
D: black x golden = all black
E: black x golden = 4/8 golden, 3/8 black, 1/8 brown
F: black x golden = 2/4 golden, ¼ black, ¼ brown
G: brown x brown = ¾ brown, ¼ golden
H: black x black = 9/16 black, 4/16 golden, 3/16 brown
