The principle of independent assortment applies to chromosomes, which are a group of genes linked together, because they are directly involved in the process. The chromosomes, not the individual genes, are the ones that assort independently during meiosis.

A gene map is used to show the relative location and the distances between genes. It allows the scientists to determine the recombination frequency of genes during crossovers.

Crossing over lets technologists determine the relative closeness of two genes. If crossing over happens fairly often between two genes, the genes must be far apart. If crossing over happens fairly rarely, the genes must be close together. Taking data about the frequency of crossing over helps to line up the genes into a gene map.

According to the studies made by Alfred Sturtevant, by finding the recombination frequency for a gene pair, we can determine the relative distances between genes. If two genes on the same chromosome are close together, the recombination is low; hence, the crossover would rarely happen. On the other hand, recombination frequency is high if the genes are distant from each other. In this case, the two genes that would usually assort independently are the ones that are far from each other.