Male Chromosomes Are Not Dying Soon, Study Finds
A new study has challenged the notion that Y chromosomes are largely unimportant and will no longer exist in the next 5 million years. The study has based its findings on a comparison of Y chromosomes in eight African and eight European men.
“The Y chromosome has lost 90 percent of the genes it once shared with the X chromosome, and some scientists have speculated that the Y chromosome will disappear in less than 5 million years,” said evolutionary biologist Melissa A. Wilson Sayres, a researcher in the Department of Integrative Biology at UC Berkeley, according to Science Recorder.
The study also acknowledged that few mammals have completely lost their Y chromosome. In December last year they were successful in engineering a male mice without Y-chromosome that was capable of producing normal offspring.
“Our study demonstrates that the genes that have been maintained, and those that migrated from the X to the Y, are important, and the human Y is going to stick around for a long while,” Sayres added.
In a paper published January 9 in the journal PLOS Genetics, researchers showed that the patterns of variation on the Y chromosome among the 16 men were consistent with the natural selection.
“Melissa’s results are quite stunning. They show that because there is so much natural selection working on the Y chromosome, there has to be a lot more function on the chromosome than people previously thought,” said Rasmus Nielsen, UC Berkeley professor of integrative biology and the author of the study.
Sayres explained that the gene that triggered a series of events that eventually results in male features are ultimately fixed on the Y chromosome. They also attract other male-specific genes such as those who control the development of testes, sperm and semen.
“Now the X and Y do not swap DNA over most of their lengths, which means that the Y cannot efficiently fix mistakes, so it has degraded over time,” she said in the press release. “In XX females, the X still has a partner to swap with and fix mistakes, which is why we think the X hasn’t also degraded.”