Dihybrid Cross

The difference between a dihybrid cross and a monohybrid cross is that a dihybrid cross involves two types of alleles at the same time.

Usually, we can figure out the offspring of a dihybrid cross in two ways. The first way is to take one allele from each trait at a time from a single parent and combine every two to form a gamete. List the male gametes on one row of the Punnett square and female gametes on the column of the Punnett square. We can have 16 genotypes from the cross and then conclude the genotypic and phenotypic ratios.

The second way is to create two Punnett squares by separating the two traits. Put one allele at a time from each parent on the sides of the square. If there were two traits such as black/brown hair and brown/blue eyes, the first Punnett square can be allele combinations for hair color and the second square for eye color. Then, we can determine the genotypic and phenotypic ratios of offspring by combining the traits of two squares.