Genetic linkage

Genetic linkage occurs when particular genetic loci or alleles for genes are inherited jointly. Genetic loci on the same chromosome are physically connected and tend to segregate together during meiosis, and are thus genetically linked. Alleles for genes on different chromosomes are usually not linked, due to independent assortment of chromosomes during meiosis.
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The situation referring to segregation of two or more genes together as a unit. Genetic linkage is thought to arise to accommodate genes that function best in each other's company, i.e., to provide a necessary cooperative effect that enhances survival. Genetic linkage reflects a lack of meiotic crossovers between two genes.