Selfish Sperm Hijack Genes to Eliminate Rivals

University of Utah study uncovers mechanism behind decades-old evolutionary mystery

Mar. 12, 2026 at 9:00am

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A new University of Utah-led study has discovered how "selfish chromosomes" cheat the rules of genetic inheritance by hijacking the Overdrive (Ovd) gene to destroy rival sperm. The researchers found that Ovd normally acts as a quality control checkpoint during sperm development, but selfish chromosomes exploit the system to kill competitors, boosting their chances of passing into the next generation.

Why it matters

The findings reveal the biology behind segregation distortion, a phenomenon in which genes sway inheritance in their favor to beat the standard 50/50 odds predicted by Mendelian genetics. The study suggests that multiple genetic systems may evolve independently to exploit the same Ovd pathway, offering new insights into male infertility and the evolution of reproductive barriers between species.

The details

The researchers knocked out the Ovd gene in two Drosophila species, each carrying completely different selfish chromosomes, and found no difference in male fertility, establishing that the gene isn't necessary for sperm production. They then exposed normal flies and flies without Ovd to high temperatures, finding that the normal fly stock was sterile while the males without Ovd produced progeny, indicating Ovd's normal function is to block the formation of potentially unhealthy sperm.

  • The version of record of the study was published on Feb. 10, 2026, in the journal Nature Communications.
  • Nearly 20 years ago, then grad student Nitin Phadnis and mentor H. Allen Orr first identified Ovd as an element in male sterility and segregation distortion in hybrids between two Drosophila species.

The players

Jackson Ridges

U biologist and lead author of the study.

Nitin Phadnis

Associate professor at the University of Utah and senior author of the study.

H. Allen Orr

Mentor to Nitin Phadnis who first identified Ovd as an element in male sterility and segregation distortion.

Jackson Bladen

Coauthor who was involved in sorting anesthetized Drosophila.

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What they’re saying

“This is the first time that the same gene has been shown to be crucial for eliminating gametes by multiple independent selfish chromosomes. It indicates that evolutionarily distant selfish chromosomes may often converge on shared cellular processes.”

— Jackson Ridges, U biologist and lead author of the study (Mirage News)

“How selfish genes can cause sterility has been a long-standing mystery in field of speciation. By going for a deep understanding of how Overdrive works, we inadvertently opened up entirely new directions of research into understanding the mechanisms of cellular quality control systems, and how sterility emerges between young species.”

— Nitin Phadnis, Associate professor at the University of Utah and senior author of the study (Mirage News)

What’s next

The team's next steps are to knock out Overdrive in different Drosophila species to assess how many other selfish chromosomes in different species operate through this system of hijacking the Overdrive checkpoint. They're also investigating if segregation distortion occurs in human lineages.

The takeaway

This study provides a breakthrough in understanding the evolutionary mechanisms behind segregation distortion, revealing how selfish chromosomes can hijack a key quality control gene to eliminate rival sperm and gain an unfair genetic advantage. The findings offer new insights into the drivers of speciation and could have implications for research into male infertility.