In a dihybrid cross, what is the ratio of phenotypes typically observed in the offspring?

In a dihybrid cross, which examines the inheritance patterns of two traits simultaneously, the expected phenotypic ratio of the offspring is 9:3:3:1. This ratio emerges from the combination of the two traits, with each trait being inherited independently according to Mendel's laws of inheritance.

When two individuals that are heterozygous for both traits are crossed (for example, AaBb x AaBb), the resulting gametes can form combinations that showcase all the potential trait expressions. The offspring phenotypes can be broken down into four categories:

• 9 individuals that display both dominant traits,

• 3 individuals that express the first dominant trait and the second recessive trait,

• 3 individuals with the first recessive trait and the second dominant trait,

• and 1 individual that exhibits both recessive traits.

This 9:3:3:1 ratio illustrates how the independent assortment of alleles contributes to the genetic variability of offspring in dihybrid crosses. The outcome is significant as it provides insight into the combination and probability of traits being passed to subsequent generations.