Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Evolution [13 p.] mojavensis cluster Y chromosome gene duplication hybrid sterility Drosophila 2025 fdi:010094972 ENG Evolution 0014-3820 ISI:001566048100001 10.1093/evolut/qpaf163 https://www.documentation.ird.fr/hor/fdi:010094972 https://www.documentation.ird.fr/intranet/publi/2025-10/010094972.pdf Early access Horizon (IRD) Y chromosomes play important roles in sex determination, male fertility, and, in some cases, hybrid male sterility. Nearly 40 years ago, Zouros and co-workers found that Drosophila mojavensis males carrying a Y chromosome from the sibling species D. arizonae are sterile, with fertility restored by chromosome 4 from D. arizonae. While these findings could result from gene interactions, they may also suggest the movement of an essential male fertility gene from the Y to chromosome 4 in the D. arizonae lineage. To test this, we analyzed the Y-linked gene content of D. mojavensis, D. arizonae, and the closely related D. navojoa. We identified 5 previously unreported Y-linked genes, bringing the total to 14. These genes fit the pattern observed in other Drosophila species: they originated from autosomal, testis-specific genes that duplicated onto the Y chromosome. All Y-linked genes are shared between D. arizonae and D. mojavensis, ruling out the movement of a protein-coding gene as the cause of sterility. However, we found a huge difference in the copy number of GI26128, an HP1 gene family member, with similar to 1,400 Y-linked copies in D. arizonae but only 6 in D. mojavensis, making it a candidate to explain the hybrid male sterility. 020 UR232 Brésil / Mexique