title: Testing for endemism, genotypic diversity and species concepts in Antarctic terrestrial microalgae of the Tribonemataceae (Stramenopiles, Xanthophyceae).
abstract: The genetic diversity of all available culture strains of the Tribonemataceae (Stramenopiles, Xanthophyceae) from Antarctica was assessed using the chloroplast-encoded psbA /rbcL spacer region sequences, a highly variable molecular marker, to test for endemism when compared with their closest temperate relatives. There was no species endemic for Antarctica, and no phylogenetic clade corresponded to a limited geographical region. However, species of the Tribonemataceae may have Antarctic populations that are distinct from those of other regions because the Antarctic strain spacer sequences were not identical to sequences from temperate regions. Spacer sequences from five new Antarctic isolates were identical to one or more previously available Antarctic strains, indicating that the Tribonemataceae diversity in Antarctic may be rather limited. Direct comparisons of the spacer sequences and phylogenetic analyses of the more conserved rbcL gene revealed that current morphospecies were inadequate to describe the actual biodiversity of the group. For example, the genus Xanthonema, as currently circumscribed, was paraphyletic. Fortunately, the presence of distinctive sequence regions within the psbA/rbcL spacer, together with differences in the rbcL phylogeny, provided significant autoapomorphic criteria to re-define the Tribonemataceae species.
authors.affiliation: Department of Botany, Taras Shevchenko National University, Kiev, Ukraine.
authors.forename: Nataliya
authors.initials: N
authors.lastname: Rybalka
authors.forename: Robert A
authors.initials: RA
authors.lastname: Andersen
authors.forename: Igor
authors.initials: I
authors.lastname: Kostikov
authors.forename: Kathrin I
authors.initials: KI
authors.lastname: Mohr
authors.forename: Andrzej
authors.initials: A
authors.lastname: Massalski
authors.forename: Maria
authors.initials: M
authors.lastname: Olech
authors.forename: Thomas
authors.initials: T
authors.lastname: Friedl
mesh_terms: D000864:Antarctic Regions; D001483:Base Sequence; D044822:Biodiversity; D016000:Cluster Analysis; D048028:DNA, Algal / Q000737:chemistry / Q000235:genetics; D018742:DNA, Chloroplast / Q000737:chemistry / Q000235:genetics; D021901:DNA, Intergenic; D056890:Eukaryota / Q000145:classification* / Q000166:cytology / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D045332:Photosystem II Protein Complex / Q000235:genetics; D010802:Phylogeny; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012988:Soil Microbiology
chemical_list: D048028:DNA, Algal; D018742:DNA, Chloroplast; D021901:DNA, Intergenic; D045332:Photosystem II Protein Complex; C422369:photosystem II, psbA subunit; C101625:RbcL protein, plastid; D012273:Ribulose-Bisphosphate Carboxylase