{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,8]],"date-time":"2026-04-08T17:04:48Z","timestamp":1775667888840,"version":"3.50.1"},"reference-count":50,"publisher":"Proceedings of the National Academy of Sciences","issue":"41","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2008,10,14]]},"abstract":"<jats:p>The coccolithophore<jats:italic>Emiliania huxleyi<\/jats:italic>is one of the most successful eukaryotes in modern oceans. The two phases in its haplodiploid life cycle exhibit radically different phenotypes. The diploid calcified phase forms extensive blooms, which profoundly impact global biogeochemical equilibria. By contrast, the ecological role of the noncalcified haploid phase has been completely overlooked. Giant phycodnaviruses (<jats:italic>Emiliania huxleyi<\/jats:italic>viruses, EhVs) have been shown to infect and lyse diploid-phase cells and to be heavily implicated in the regulation of populations and the termination of blooms. Here, we demonstrate that the haploid phase of<jats:italic>E. huxleyi<\/jats:italic>is unrecognizable and therefore resistant to EhVs that kill the diploid phase. We further show that exposure of diploid<jats:italic>E. huxleyi<\/jats:italic>to EhVs induces transition to the haploid phase. Thus we have clearly demonstrated a drastic difference in viral susceptibility between life cycle stages with different ploidy levels in a unicellular eukaryote. Resistance of the haploid phase of<jats:italic>E. huxleyi<\/jats:italic>provides an escape mechanism that involves separation of meiosis from sexual fusion in time, thus ensuring that genes of dominant diploid clones are passed on to the next generation in a virus-free environment. These \u201cCheshire Cat\u201d ecological dynamics release host evolution from pathogen pressure and thus can be seen as an opposite force to a classic \u201cRed Queen\u201d coevolutionary arms race. In<jats:italic>E. huxleyi<\/jats:italic>, this phenomenon can account for the fact that the selective balance is tilted toward the boom-and-bust scenario of optimization of both growth rates of calcifying<jats:italic>E. huxleyi<\/jats:italic>cells and infectivity of EhVs.<\/jats:p>","DOI":"10.1073\/pnas.0807707105","type":"journal-article","created":{"date-parts":[[2008,9,30]],"date-time":"2008-09-30T01:09:51Z","timestamp":1222736991000},"page":"15944-15949","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":195,"title":["The \u201cCheshire Cat\u201d escape strategy of the coccolithophore<i>Emiliania huxleyi<\/i>in response to viral infection"],"prefix":"10.1073","volume":"105","author":[{"given":"Miguel","family":"Frada","sequence":"first","affiliation":[{"name":"*Station Biologique, Equipe EPPO-Evolution du Plancton et Pal\u00e9oOc\u00e9ans, Centre National de la Recherche Scientifique et Universit\u00e9 Pierre et Marie Curie (Unit\u00e9 Mixte de Recherche 7144), Station Biologique, 29682 Roscoff, France;"},{"name":"Departamento de Geologia, Faculdade de Ci\u00eancias, Universidade de Lisboa, Edificio C6, Campo Grande, 1749-016 Lisbon, Portugal;"}]},{"given":"Ian","family":"Probert","sequence":"additional","affiliation":[{"name":"*Station Biologique, Equipe EPPO-Evolution du Plancton et Pal\u00e9oOc\u00e9ans, Centre National de la Recherche Scientifique et Universit\u00e9 Pierre et Marie Curie (Unit\u00e9 Mixte de Recherche 7144), Station Biologique, 29682 Roscoff, France;"}]},{"given":"Michael J.","family":"Allen","sequence":"additional","affiliation":[{"name":"Bigelow Laboratory for Ocean Sciences, 180 McKown Point, P.O. Box 475, West Boothbay Harbor, ME 04575-0475"}]},{"given":"William H.","family":"Wilson","sequence":"additional","affiliation":[{"name":"Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH, United Kingdom; and"}]},{"given":"Colomban","family":"de Vargas","sequence":"additional","affiliation":[{"name":"*Station Biologique, Equipe EPPO-Evolution du Plancton et Pal\u00e9oOc\u00e9ans, Centre National de la Recherche Scientifique et Universit\u00e9 Pierre et Marie Curie (Unit\u00e9 Mixte de Recherche 7144), Station Biologique, 29682 Roscoff, France;"}]}],"member":"341","published-online":{"date-parts":[[2008,10,14]]},"reference":[{"key":"e_1_3_3_1_2","first-page":"251","volume-title":"Evolution of Aquatic Photoautotrophs","author":"de Vargas C","year":"2007","unstructured":"C de Vargas, MP Aubry, I Probert, J Young, Origin and evolution of coccolithophores: From coastal hunters to oceanic farmers. 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