{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T06:04:17Z","timestamp":1782281057908,"version":"3.54.5"},"posted":{"date-parts":[[2026,2,9]]},"group-title":"Evolutionary Biology","reference-count":32,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,2,9]],"date-time":"2026-02-09T00:00:00Z","timestamp":1770595200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"name":"Intramural Research Program of the NIAID, NIH"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,2,6]]},"abstract":"<jats:title>Summary<\/jats:title>\n                <jats:p>\n                  Genetic exchange in\n                  <jats:italic>Leishmania<\/jats:italic>\n                  is established, yet the molecular mechanisms enabling hybrid formation in sand flies remain poorly defined. In\n                  <jats:italic>Leishmania<\/jats:italic>\n                  , as in plants and several protists, two paralogs of the conserved meiotic endonuclease SPO11 are present, but their contribution to hybridization is unknown. Here, we dissect the roles of SPO11-1 and SPO11-2 during in vivo sand fly infections using targeted gene deletions, catalytically-dead mutants, expression analyses, and genome-wide characterization of hybrid progeny. We show that both SPO11 paralogs are essential for efficient hybridization: deletion of either paralog in both parents abolishes hybrid recovery, and catalytic inactivation fails to rescue mating. When only one parent lacks SPO11-1 or SPO11-2, hybrid formation is reduced in a strain-dependent manner, revealing asymmetric requirements for each paralog. Genomic analysis of hybrids from SPO11-deficient crosses reveals polyploidy and altered parental genome contributions, including unbalanced and near-balanced triploid configurations, indicating disrupted reductional processes. Together, these results establish SPO11-dependent DNA break formation as a core requirement for\n                  <jats:italic>Leishmania<\/jats:italic>\n                  hybridization and define distinct, strain-specific roles for the two SPO11 paralogs.\n                <\/jats:p>\n                <jats:sec>\n                  <jats:title>Highlights<\/jats:title>\n                  <jats:list list-type=\"simple\">\n                    <jats:list-item>\n                      <jats:label>\u25a1<\/jats:label>\n                      <jats:p>\n                        <jats:italic>Leishmania<\/jats:italic>\n                        encodes two non-redundant\n                        <jats:italic>SPO11<\/jats:italic>\n                        paralogs that are differentially required in each mating partner for efficient hybridization.\n                      <\/jats:p>\n                    <\/jats:list-item>\n                    <jats:list-item>\n                      <jats:label>\u25a1<\/jats:label>\n                      <jats:p>The catalytic activity of SPO11 is essential, indicating conservation of its ancestral mode of action.<\/jats:p>\n                    <\/jats:list-item>\n                    <jats:list-item>\n                      <jats:label>\u25a1<\/jats:label>\n                      <jats:p>Loss of either paralog disrupts reductional division and prevents balanced genome segregation.<\/jats:p>\n                    <\/jats:list-item>\n                    <jats:list-item>\n                      <jats:label>\u25a1<\/jats:label>\n                      <jats:p>\n                        Cell fusion proceeds without\n                        <jats:italic>SPO11<\/jats:italic>\n                        , revealing a separation between fusion and meiosis-like functions.\n                      <\/jats:p>\n                    <\/jats:list-item>\n                    <jats:list-item>\n                      <jats:label>\u25a1<\/jats:label>\n                      <jats:p>\n                        <jats:italic>SPO11<\/jats:italic>\n                        -deficient hybrids show widespread aneuploidy and highly distorted parental genome contributions.\n                      <\/jats:p>\n                    <\/jats:list-item>\n                  <\/jats:list>\n                <\/jats:sec>","DOI":"10.64898\/2026.02.05.703715","type":"posted-content","created":{"date-parts":[[2026,2,9]],"date-time":"2026-02-09T16:05:11Z","timestamp":1770653111000},"source":"Crossref","is-referenced-by-count":0,"title":["Cryptic Sex in\n                  <i>Leishmania<\/i>\n                  Depends on\n                  <i>SPO11<\/i>\n                  Paralogs"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8983-3487","authenticated-orcid":false,"given":"C.M.C.","family":"Catta-Preta","sequence":"first","affiliation":[{"name":"Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA"},{"name":"Department of Parasitology, Institute of Biomedical Sciences, University of S\u00e3o Paulo, S\u00e3o Paulo, SP, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7308-4044","authenticated-orcid":false,"given":"V.L.","family":"Da Silva","sequence":"additional","affiliation":[{"name":"Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA"},{"name":"Department of Biochemistry, Institute of Chemistry, University of S\u00e3o Paulo (USP), S\u00e3o Paulo, SP, Brazil"},{"name":"Department of Chemical and Biological Sciences, S\u00e3o Paulo State University (UNESP), Botucatu, SP, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"C.","family":"Meneses","sequence":"additional","affiliation":[{"name":"Laboratory of Malaria and Vector Research, Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K.","family":"Ghosh","sequence":"additional","affiliation":[{"name":"Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D.L.","family":"Sacks","sequence":"additional","affiliation":[{"name":"Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 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