What is the Ratio of Dihybrid Cross?

The ratio of a dihybrid cross represents the expected proportion of different genotypes in the offspring resulting from the mating of two individuals heterozygous for two different genes.

In a dihybrid cross, two traits governed by different genes are considered simultaneously. Each gene can have two alleles, one dominant and one recessive, denoted by capital and lowercase letters, respectively. When two heterozygous individuals (RrYy x RrYy ) are crossed, the Punnett square is used to determine the possible genotypes in their offspring.

The resulting genotype ratio is typically 9:3:3:1, representing four possible combinations:

1. 9/16 will have both dominant traits (R_Y_).
2. 3/16 will have the first dominant trait and the second recessive trait (R_yy).
3. 3/16 will have the first recessive trait and the second dominant trait (rrY_).
4. 1/16 will have both recessive traits (rryy).

This 9:3:3:1 ratio demonstrates the expected genetic outcomes of a dihybrid cross and helps predict the genetic diversity of offspring for two traits simultaneously.