Morphology, Genome Plasticity, and Phylogeny in the Genus
Protist, Vol. 164, 643–659, xx 2013 http://www.elsevier.de/protis Published online date xxx ORIGINAL PAPER Morphology, Genome Plasticity, and Phylogeny in the Genus Ostreococcus Reveal a Cryptic Species, O. mediterraneus sp. nov. (Mamiellales, Mamiellophyceae) a,b c d a,b Lucie Subirana , Bérangère Péquin , Stéphanie Michely , Marie-Line Escande , a,b,2 a,b e a,b Julie Meilland , Evelyne Derelle , Birger Marin , Gwenaël Piganeau , a,b a,b a,b,1 Yves Desdevises , Hervé Moreau , and Nigel H. Grimsley a CNRS, UMR7232 Laboratoire de Biologie Intégrative des Organisms Marins (BIOM), Observatoire Océanologique, Banyuls-sur-Mer, France b UPMC Univ Paris 06, Observatoire Océanologique, Banyuls-sur-Mer, France c Québec-Océan, Département de Biologie and Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec (QC) G1 V 0A6, Canada d INRA UMR1319, AgroParisTech, Micalis, Bimlip, Bât. CBAI, BP 01, 78850 Thiverval-Grignon, France e Biozentrum Köln, Botanisches Institut, Universität zu Köln, Zülpicher Str. 47b, 50674 Köln, Germany Submitted December 4, 2011; Accepted June 18, 2013 Monitoring Editor: David Moreira Coastal marine waters in many regions worldwide support abundant populations of extremely small (1-3 m diameter) unicellular eukaryotic green algae, dominant taxa including several species in the class Mamiellophyceae. Their diminutive size conceals surprising levels of genetic diversity and defies classical species’ descriptions. We present a detailed analysis within the genus Ostreococcus and show that morphological characteristics cannot be used to describe diversity within this group. Karyotypic analyses of the best-characterized species O. tauri show it to carry two chromosomes that vary in size between individual clonal lines, probably an evolutionarily ancient feature that emerged before species’ divergences within the Mamiellales.
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