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bioRxiv · 10.64898/2026.07.28.741199

Re-inventing sex: A W chromosome and a path out of parthenogenesis for Bunonema nematodes

Fierst, J. L.·Arbex Herden, L.·Eggers, V. K.·Burns, C. A.·Sosa, J. A.·Kayastha, P.·McCauley, M. A.·Willicott, K.
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Abstract

Sex chromosomes are deeply conserved in some organisms but remarkably labile in others. Here we describe the evolution of a novel sex chromosome in the nematode Bunonema JU3390, a species with an autosome-derived genomic segment currently functioning as a female-limited W chromosome. We propose this neo sex chromosome system evolved to escape lethal structural mutations accumulated during a period of parthenogenesis, demonstrating the role of evolutionary contingency in this rapid re-invention of sex.

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Fierst, J. L., Arbex Herden, L., Eggers, V. K., Burns, C. A., Sosa, J. A., Kayastha, P., McCauley, M. A., Willicott, K.. 2026-07-30. Re-inventing sex: A W chromosome and a path out of parthenogenesis for Bunonema nematodes. https://doi.org/10.64898/2026.07.28.741199

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