Evolutionary dynamics of enlarged sex chromosomes and novel pseudoautosomal regions in Sylvioidea songbirds

Evolutionary dynamics of enlarged sex chromosomes and novel pseudoautosomal regions in Sylvioidea songbirds | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Evolutionary dynamics of enlarged sex chromosomes and novel pseudoautosomal regions in Sylvioidea songbirds Bengt Hansson, Hanna Sigeman, Simon Ellerstrand This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6395738/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Sex chromosomes often contain recombining pseudoautosomal regions (PARs). Uncovering the dynamics of PAR is crucial for understanding sex chromosome evolution. We analyse PAR dynamics in Sylvioidea songbird neo-sex chromosomes formed by multiple sex chromosome–autosome fusions. We show that the otherwise highly conserved ancestral songbird PAR has stopped recombining independently multiple times when novel PARs formed in the new sex-linked regions. Such PAR transitions were associated with PAR-end fusions, but resulted from subsequent recombination suppression events rather than the fusions themself. We provide support for the hypothesis that episodes of recombination suppression are preceded by sex-associated sequence divergence close to the PAR boundary, and suggest that PAR-end fusions have released the ancestral PAR from constraints in evolving recombination suppression and allowed PAR transitions along the neo-sex chromosomes. This study reveals exceptional PAR diversity among birds and provides novel insights into the process of recombination suppression. Biological sciences/Evolution/Evolutionary genetics Biological sciences/Genetics/Evolutionary biology Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SigemanetalSupplementaryCode29April2025.zip Supplementary Code SigemanetalSupplementaryTables29April2025.pdf Supplementary Tables SigemanetalSupplementaryFigures29April2025.pdf Supplementary Figures Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6395738","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":456048512,"identity":"92980fb8-18fa-4b41-a1e3-dacc581175a2","order_by":0,"name":"Bengt 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