Cryptic invasion by non-native reed canary grass, Phalaris arundinacea, in Japan endangers native conspecific populations through displacement and hybridization

Cryptic invasion by non-native reed canary grass, Phalaris arundinacea, in Japan endangers native conspecific populations through displacement and hybridization | 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 Research Article Cryptic invasion by non-native reed canary grass, Phalaris arundinacea, in Japan endangers native conspecific populations through displacement and hybridization Satoshi Yamamoto, Chika Egawa, Yasuyuki Yoshimura, Natsumi Ueda, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7457695/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 Invasions by non-native conspecific populations can result in genetic disturbance and even local extinction of native populations. In cases of intraspecific cryptic invasion, where distinction between native and non-native individuals by morphology is difficult, it is challenging to delineate the extent of invasion and assess its ecological impact. Phalaris arundinacea is a cosmopolitan grass species native to Eurasia and North America. Although it is also native to Japan, commercial strains from the USA have been introduced and grown for nearly 150 years. The cryptic spread of these non-native genotypes has raised concerns regarding their impact on native populations. Here, we investigated the distributions of native, non-native, and admixed P. arundinacea in eastern and northern Japan. We collected over 270 individuals in the Hokkaido, Tohoku, Kanto, and Koshinetsu regions and analyzed genome-wide single nucleotide polymorphisms and chloroplast sequences. Nearly all individuals north of 39.7°N were genetically identified as purely non-native, whereas admixed individuals were widespread south of this latitude. These findings suggest that the effect of non-native P. arundinacea on native individuals varies by region: native individuals have been largely displaced in the Hokkaido and northern Tohoku regions and genetically introgressed in the rest of the Tohoku region. Furthermore, in the Kanto region, pure native genotypes were detected only in a restricted area. Native populations in both eastern and northern Japan are at substantial risk of local extinction. Alien species genetic disturbance SNP admixture analysis Full Text Supplementary Files TableS10713.xlsx TableS20713.xlsx 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-7457695","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":511519574,"identity":"b85685a1-b30b-484d-97bc-0dab4e086309","order_by":0,"name":"Satoshi 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In cases of intraspecific cryptic invasion, where distinction between native and non-native individuals by morphology is difficult, it is challenging to delineate the extent of invasion and assess its ecological impact. \u003cem\u003ePhalaris arundinacea\u003c/em\u003e is a cosmopolitan grass species native to Eurasia and North America. Although it is also native to Japan, commercial strains from the USA have been introduced and grown for nearly 150 years. The cryptic spread of these non-native genotypes has raised concerns regarding their impact on native populations. Here, we investigated the distributions of native, non-native, and admixed \u003cem\u003eP. arundinacea\u003c/em\u003e in eastern and northern Japan. We collected over 270 individuals in the Hokkaido, Tohoku, Kanto, and Koshinetsu regions and analyzed genome-wide single nucleotide polymorphisms and chloroplast sequences. 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