Meiotic drive

Meiotic drive is the disproportionate appearance of an allele among a set of gametes. All nuclear genes in a given diploid genome usually cooperate because each allele has an equal probability of being present in a gamete. This fairness is guaranteed by meiosis. However, there is one type of gene, called a segregation distorter, which "cheats" during meiosis and thus is present in more than half of the functional gametes. Segregation distorters that are present on sex chromosomes (as the X chromosome in several Drosophila species) are denominated sex-ratio distorters, as they induce a sex-ratio bias in the offspring of the carrier individual.