Murat, F.Mbengue, N.Winge, S.B.Trefzer, T.Leushkin, E.Sepp, M.Cardoso-Moreira, M.Schmidt, J.Schneider, C.Mößinger, K.Brüning, T.Lamanna, F.Belles, M.R.Conrad, C.Kondova, I.Bontrop, R.Behr, R.Khaitovich, P.Pääbo, S.Marques-Bonet, T.et al.2023-03-082023-03-082023Nature, 2023; 613(7943):308-3160028-08361476-4687https://hdl.handle.net/2440/137500The testis produces gametes through spermatogenesis and evolves rapidly at both the morphological and molecular level in mammals1–6 , probably owing to the evolutionary pressure on males to be reproductively successful7 . However, the molecular evolution of individual spermatogenic cell types across mammals remains largely uncharacterized. Here we report evolutionary analyses of singlenucleus transcriptome data for testes from 11 species that cover the three main mammalian lineages (eutherians, marsupials and monotremes) and birds (the evolutionary outgroup), and include seven primates. We fnd that the rapid evolution of the testis was driven by accelerated fxation rates of gene expression changes, amino acid substitutions and new genes in late spermatogenic stages, probably facilitated by reduced pleiotropic constraints, haploid selection and transcriptionally permissive chromatin. We identify temporal expression changes of individual genes across species and conserved expression programs controlling ancestral spermatogenic processes. Genes predominantly expressed in spermatogonia (germ cells fuelling spermatogenesis) and Sertoli (somatic support) cells accumulated on X chromosomes during evolution, presumably owing to male-benefcial selective forces. Further work identifed transcriptomal diferences between X- and Y-bearing spermatids and uncovered that meiotic sex-chromosome inactivation (MSCI) also occurs in monotremes and hence is common to mammalian sex-chromosome systems. Thus, the mechanism of meiotic silencing of unsynapsed chromatin, which underlies MSCI, is an ancestral mammalian feature. Our study illuminates the molecular evolution of spermatogenesis and associated selective forces, and provides a resource for investigating the biology of the testis across mammals.en© The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Chromosomes; Evolutionary genetics; Gene expression profiling; Molecular evolution; Sexual selectionTestisSertoli CellsSpermatogoniaX ChromosomeY ChromosomeChromatinAnimalsBirdsMammalsPrimatesEvolution, MolecularMeiosisSpermatogenesisGene Expression RegulationGene SilencingDosage Compensation, GeneticMaleSingle-Cell AnalysisTranscriptomeJournal article10.1038/s41586-022-05547-72023-03-08630754