Selfish X Chromosome in Fruit Flies Cheats Meiosis in Both Sexes

Scientists have discovered a selfish X chromosome in *Drosophila testacea* [druh-ZOH-fuh-luh tes-TEH-see-uh] that defies traditional genetic inheritance. Researchers at the University of British Columbia and the University of Victoria identified this chromosome. It manipulates meiosis [my-OH-sis] in both male and female fruit flies. This selfish X chromosome biases its transmission through sperm and eggs. It reveals a sophisticated mechanism of genetic conflict. Lead author Graeme Keais [GREEM KEY-iss] explains that previous research focused on sex-specific meiotic drive. "This is the first known instance of a selfish chromosome that successfully distorts inheritance in the gametes of both sexes," he stated. The selfish X chromosome targets the testes and ovaries. In males, it eliminates Y-bearing sperm, favoring female offspring. In females, it is preferentially included during egg cell division. Dr. Steve Perlman [STEEV PERL-muhn] highlights the chromosome's adaptability. He stated that it demonstrates "the astonishing adaptability of selfish genetic elements." The selfish X chromosome acts as a supergene [SOO-per-jeen], a cluster of linked genes that don't recombine. It has expanded to nearly twice the size of a typical X chromosome. This expansion is due to the accumulation of repetitive DNA sequences. These sequences may enable its cheating behavior during female meiosis. This discovery impacts understanding of population genetics. It also influences sex ratios and species evolution. The research employed observational methods and molecular assays. These methods analyzed genetic inheritance patterns and characterized the chromosome's structure. The findings reshape evolutionary theory and genome biology.