Meiotic drive

Definition

A form of intragenomic conflict in which one or more loci manipulate the meiotic process to bias transmission of particular alleles or chromosomal regions to offspring at frequencies greater than the Mendelian expectation of 50%. This segregation distortion can operate through preferential inclusion in functional gametes, destruction of competing gametes, or biased chromosome segregation, and represents a powerful evolutionary force that can spread deleterious alleles, reshape genome architecture, and drive speciation.

Etymology

From Greek 'meiosis' (reduction, diminution) + 'drive' (propelling force), reflecting the forced transmission of genetic material.

Example

In Drosophila melanogaster, the Segregation Distorter (SD) system on chromosome 2 causes nearly 100% transmission of the SD-bearing chromosome in males by inducing dysfunction of sperm carrying the wild-type allele, despite severe fertility costs to the carrier.

Synonyms

• segregation distortion
• transmission ratio distortion

Related Terms

• intragenomic conflict
• selfish genetic element
• Mendelian inheritance
• gamete competition
• speciation
• t-complex

Usage Notes

Distinguished from gamete competition (post-meiotic) and zygotic drive (post-fertilization). In arthropods, meiotic drive systems are well-documented in Diptera and Lepidoptera and can influence sex ratios when drive occurs on sex chromosomes. The term is sometimes used broadly to include both meiotic and post-meiotic mechanisms; specialists may prefer 'segregation distortion' for the broader phenomenon.