Law of Independent Assortment

The law of independent assortment states that genes for different traits are sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene (assuming the genes are on different chromosomes or far apart on the same chromosome).

• Independent assortment is illustrated by a dihybrid cross: e.g., in peas, seed color and seed shape alleles assort independently, producing the classic 9:3:3:1 ratio in the F2 generation.
• This law holds true for genes located on separate chromosomes (or sufficiently far apart on the same chromosome). Genes that are close together on the same chromosome may be linked, which is an exception to independent assortment.
• Remember: independent assortment is about multiple genes. Don't confuse it with the law of segregation (which is about the two alleles of one gene separating).

• Genetics questions involving two traits often rely on this law. For example, a problem might state that one trait is inherited independently of another - indicating no linkage and an application of independent assortment.
• If an exam asks why all combinations of traits occur in offspring (even combinations not seen in the parents), the answer is usually independent assortment during meiosis (unless linkage is involved).