X chromosome causes disprortionately more speciation, new U/Rochester research shows.

"Researchers at the University of Rochester believe they have just confirmed a controversial theory of evolution. The X chromosome is a strikingly powerful force in the origin of new species. Biologists have argued for years whether the X chromosome—the female chromosome in most animals—plays a special role in the process of speciation. In a new study in the journal PLoS Biology, Daven Presgraves, professor of biology at the University of Rochester, has confirmed that the X chromosome is indeed heavily influential—and the reason may be nothing like what biologists expected."