Causes and consequences of sex-chromosome turnovers in Diptera Layana Franco, Lorena Alexandra ; https://orcid.org/0000-0002-1253-6297 Toups, Melissa A ; https://orcid.org/0000-0002-9752-7380 Vicoso, Beatriz ; https://orcid.org/0000-0002-4579-8306 ddc:570 Sex-chromosome systems are highly variable across animals, but how they transition from one to another is not well understood. Diptera have undergone multiple sex-chromosome turnovers and expansions while maintaining their general chromosomal content, which makes them an ideal clade to study such transitions. We analyzed more than 100 dipteran whole-genome assemblies and identified 4 new lineages that underwent sex-chromosome turnover (in addition to the 5 previously reported). We find that the majority of turnovers happened in the group Schizophora, which tend to have fewer genes on Muller element F (the chromosome homologous to the ancestral insect X chromosome) than lower dipterans, a factor previously hypothesized to facilitate turnover. Most derived X chromosomes have higher GC content than autosomes, consistent with a high prevalence of male achiasmy in Diptera. In addition, an excess of gene movement out of the X is detected for most of these new X chromosomes, and many of these moved genes have high testis expression in Drosophila, suggesting that out-of-X gene movement contributes to the long-term demasculinization of X chromosomes. Oxford University Press 2026 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/21486 Layana Franco LA, Toups MA, Vicoso B. Causes and consequences of sex-chromosome turnovers in Diptera. <i>Evolution Letters</i>. 2026. doi:<a href="https://doi.org/10.1093/evlett/qrag003">10.1093/evlett/qrag003</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1093/evlett/qrag003 info:eu-repo/semantics/altIdentifier/e-issn/2056-3744 https://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess