linkage

Genetic linkage describes the way in which two genes that are located close to each other on a chromosome are often inherited together. In 1905, William Bateson, Edith Rebecca Saunders, and Reginald C. Punnett noted that the traits for flower color and pollen shape in sweet pea plants appeared to be linked together. A few years later, in 1911, Thomas Hunt Morgan, who was studying heredity in fruit flies, noticed that the eye color of a fly was associated with the fly's sex and hypothesized that the two traits were linked together. These observations led to the concept of genetic linkage, which describes how two genes that are closely associated on the same chromosome are frequently inherited together. In fact, the closer two genes are to one another on a chromosome, the greater their chances are of being inherited together or linked. In contrast, genes located farther away from each other on the same chromosome are more likely to be separated during recombination, the process that recombines DNA during meiosis. The strength of linkage between two genes, therefore, depends upon the distance between the genes on the chromosome.

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