In rabbits, spotted coat (S) is dominant to solid color (s) and black (B) is dominant to brown (b). A true-breeding black spotted rabbit is mated to a true-breeding brown solid rabbit to produce a heterozygous F1 generation. Two F1 individuals are mated, and you do not see the typical 9:3:3:1 ratio of offspring, so you take an F1 rabbit and perform a test cross. Instead of the expected ratio, you see that most progeny look like the parental rabbits but a few are new, unique phenotype. This tells you that: