title: Phylogeographical pattern of Euplotes nobilii, a protist ciliate with a bipolar biogeographical distribution.
abstract: Nuclear (18S and ITS) and mitochondrial (16S) ribosomal RNA gene sequences were determined from genetically distinct wild-type strains of Antarctic (nine strains), Fuegian (four strains), Greenland (nine strains) and Svalbard (three strains) populations of the marine ciliate, Euplotes nobilii, and analysed for their nucleotide polymorphisms. A close genetic homogeneity was found within and between the Antarctic and Fuegian populations, while more significant levels of genetic differentiation were detected within and between the two Arctic populations, as well as between these populations and the Antarctic/Fuegian ones. The phylogeographical pattern that was derived from these data indicates that gene flow is not limited among Arctic populations; it equally connects the Arctic and Antarctic populations either directly, or through the Fuegian population. This indication reinforces previous evidence from laboratory assays of mating interactions between some of the strains analysed in this work that Southern and Northern polar populations of E. nobilii belong to a unique, panmictic population that substantially share the same gene pool.
authors.affiliation: Department of Biology, University of Pisa, 56126, Pisa, Italy. gdigiuseppe@biologia.unipi.it
authors.forename: Graziano
authors.initials: G
authors.lastname: Di Giuseppe
authors.forename: Michele
authors.initials: M
authors.lastname: Barbieri
authors.forename: Adriana
authors.initials: A
authors.lastname: Vallesi
authors.forename: Pierangelo
authors.initials: P
authors.lastname: Luporini
authors.forename: Fernando
authors.initials: F
authors.lastname: Dini
mesh_terms: D000864:Antarctic Regions; D059001:Aquatic Organisms / Q000235:genetics; D001110:Arctic Regions; D001483:Base Sequence; D004251:DNA Transposable Elements / Q000235:genetics; D016812:Euplotes / Q000235:genetics*; D051456:Gene Flow / Q000235:genetics*; D014644:Genetic Variation; D006116:Greenland; D008928:Mitochondria / Q000235:genetics; D058974:Phylogeography; D020641:Polymorphism, Single Nucleotide; D015138:RNA, Nuclear / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013538:Svalbard
chemical_list: D004251:DNA Transposable Elements; D015138:RNA, Nuclear; D012336:RNA, Ribosomal, 16S
keywords: bipolar species; microbial biogeography; natural hybrids; nuclear and mitochondrial rRNA gene sequences; protists