Recombination

Definition

The exchange of genetic material between homologous chromosomes or DNA molecules, producing new combinations of alleles and increasing genetic diversity in offspring. In sexual reproduction, recombination occurs during meiosis through crossing over between paired chromosomes; in bacteria and viruses, it occurs through horizontal gene transfer mechanisms. This process is a major source of the genetic variation that underlies adaptation, speciation, and the evolution of traits such as insecticide resistance in arthropod populations.

Etymology

From Latin re- (again) + combinare (to combine), referring to the reshuffling of genetic material into new arrangements.

Example

In the mosquito Culex pipiens, recombination between different resistance alleles at the acetylcholinesterase locus has produced novel haplotypes conferring heightened resistance to organophosphate insecticides.

Synonyms

• Crossing over
• genetic reshuffling

Related Terms

• Crossing over
• Meiosis
• linkage
• haplotype
• genetic drift
• Gene flow
• Horizontal gene transfer
• insecticide resistance

Usage Notes

Distinguish from 'crossing over,' which specifically describes the physical exchange of chromosomal segments during meiosis, whereas recombination encompasses all mechanisms that generate new allele combinations. In population genetics, recombination rate varies across the genome and influences the effectiveness of selection. Recombination frequency is used to map gene positions in genetic linkage studies of model arthropods such as Drosophila melanogaster.