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Protistology ■ 7
km2. Thus, since their commissioning approximately five decades ago, the ponds have accumulated anoxic, brackish, hydrocarbon and heavy metal containing sediments overlain by a thinner layer of process-affected water that may be oxic near the surface. Microbial processes are anticipated to play a major role in remediation of these environments, and, although the prokaryotic communities are increasingly well-characterized, little is known about the microbial eukaryotes present in the oxic and anoxic environments. We have recently reported the first NGS-based exploration of protists in tailings ponds. We found that, despite the anoxic and hydrocarbon-enriched nature of the environment, the tailings ponds harbour complex communities of microbial eukaryotes indicating that these organisms should be taken into account when studying the microbiology of the oil sands.
NOVEL PICOPLANKTONIC GROUPS FROM LAKE BAIKAL REVEALED BY MASSIVE SEQUENCING
Annenkova N.V.1, Logares R.2
1 - Limnological Institute SB RAS, Russia
2 - Institute of Marine Sciences, CSIC, Spain [email protected]
Compared to the ocean, freshwater systems offer multiple ecological niches in terms of oxygen and DOC concentrations, light accessibility, temperature variability. However, we are still limited by the data of freshwater microbes biodiversity. Studies are highly biased because correspond mainly to Europe and North America. In particular, studies of Northern Asian protists are very limited, though this region extends on about 8000 km in length and has a big impact on microorganisms' migrations. Lake Baikal is the oldest and deepest lake in the world, being located in Northern Asia. It is cold, oxygen rich, and has one ofthe world richest endemic freshwater biotas, belonging both to very ancient lineages and to recent immigrants. Our goal was to explore small planktonic protists populating the lake. The genetic diversity (V4 region ofthe 18S rDNA) of planktonic microeukaryotes (< 8 ^m fraction) was analyzed in 48 samples using the Illumina MiSeq platform. We determined 1,461 protist OTUs, with 9.6% of them having less than 90% similarity with sequences from SILVA database. We suggest that they belong to endemic Baikal protists. We analyzed the phylogenetic relationships ofgroups such as MAST, Telonemiidae, Perkinsiidae, Chitridiomycota which were not previously described in Lake Baikal. Interestingly, we found Amoebophrya-like 18S rDNA in Baikal, even though Syndiniales were not reported from freshwaters. Overall, the most diverse
group was stramenopiles. This study contributes to improve our understanding of the diversity of protist communities living in ancient lakes as well as to comprehend better intra-lake evolutionary diversification processes. Supported by project of RAS # 0345-2014-0003
MODELLING THE LOCAL-TO-GLOBAL DIVERSITY FOR MICROBES AND MULTICELLULARS: COULD WE ESTIMATE THE NEAR-IMPONDERABLE? Azovsky A.I.
Lomonosov Moscow State University, Moscow, Russia [email protected]
In the current discussion around either "protist diversity is different" or not, the ratios oflocal:global diversity and relative endemicity are often treated as arguments. This approach has, however, been flawed by the fact that actual global diversity of protists is still largely unknown, especially for the rare species. I use simple models to simulate distribution of species on the 400-cell lattice. Three models have been considered:
1) "Everything is everywhere" (equal probability for a particular species to occur at every cell);
2) "Environmental selection" (a species can occupy only a fixed portion of randomly distributed "suitable localities"); and
3) "Endemicity" (most of species are restricted in its potential distribution to a few regions).
To parameterize the models, several world-wide datasets on ciliates, flagellates and harpacticoid copepods were used. The local:regional and re-gional:global diversity ratios and percentage of endemics were estimated by simulating the equal-effort sampling across the lattice, with varying the full number of species ("actual diversity") and number of samplings per cell ("sampling effort"). All parameters, predicted by every model, strongly depended on the sampling effort but were only slightly, if ever, influenced by the observed:actual global diversity ratio. The predictions of the first two models were generally close to each other, but differed noticeably from those of the third one. These results indicate that the above-mentioned parameters are heavily influenced by undersampling. Nevertheless, they can serve as informative characteristics in comparative biodiversity studies, even ifthe true number of species can hardly be estimated overall.
GLOBAL DIVERSITY AND DISTRIBUTION OF MARINE BENTHIC HETEROTROPHIC FLAGELLATES
Azovsky A.I.1, Tikhonenkov D.V.23
8 • "PROTIST—2016
1 - Lomonosov Moscow State University, Moscow, Russia
2 - Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, Russia
3 - University of British Columbia, Department of Botany, Vancouver, BC, Canada [email protected]
Protists are ubiquitous, but the factors influencing their diversity and biogeography are poorly understood. We use a comprehensive database on the marine benthic heterotrophic flagellate (HF) morphospecies to explore the worldwide patterns in their diversity and distribution in comparison with predictions of the Ubiquity model (UM) and Moderate Endemicity model (MEM). Number of known HF morphospecies was limited (even if considering the rates of descriptions), and local-to-global diversity ratio was relatively high (10-25%). Regional diversity was highly correlated with the investigation effort, indicating considerable under-exploration. Regional endemics were few (not over 19% of total richness), and many morphospecies were widespread or even cosmopolitan. No obvious latitudinal trend in HF diversity was detected. By species composition, the regions were distinctly arranged into three groups according to cold, temperate and warm waters, but not in accordance with geographical distances. This distribution pattern was most likely explained by contemporary climate (temperature) but did not suggest clear geographical barriers for dispersal. Therefore, the HF morphospecies are less concordant with the MEM predictions but closer to the UM than other (larger) protists. (In)consistency between the distributional patterns obtained from genetic- and morphology-based data are briefly discussed. This study was supported by Russian Foundation for Basic Research (grants № 15-04-02245 to AA and № 14-04-00553, 15-29-02518 to DT).
MOLECULAR DIVERSITY OF SUMMER PLANKTON PICOEUKARYOTES IN THE WHITE SEA
Belevich T.A.1, Ilyash L.V.1, Milyutina I.A.2, Logacheva M.D.2, Goryunov D.V.2, Troitsky A.V.2
1 - Lomonosov Moscow State University, Faculty of Biology
2 - Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University [email protected]
Picoeukaryotes (protists < 2 ^m) play an important role in marine ecosystems, although knowledge of their diversity and ecosystem functioning is limited. The White Sea is located in the sub-Arctic zone.
However, its abiotic conditions are characterized by a number offeatures typical ofthe Arctic seas. In this study, the molecular diversity of picoeukaryotes in July 2014 in Kandalaksha Bay (the White Sea) was examined using conventional filter fractionation and Illumina sequencing. In < 2 ^m size fraction 186 taxa were revealed that included some nanoplankton (2—20 ^m) and even microplankton (>20 ^m) taxa. Plankton assemblage was prevailed by autotrophs (>57% of all sequences). Putative picoeukaryotic autotrophs were mostly dominated by three genus: Micromonas sp., Bathycoccus sp. and Ostreococcus sp. (35% of all sequences). Putative heterotrophic picoeukaryote assemblage was more diverse and was presented by marine stramenopiles (MAST, Labyrinthulomycetes), Amoebozoa, Cercozoa and picozoa. Illumina sequencing revealed some new groups and genus of nano- and microplankton organisms which have been never detected in the White Sea. Our study revealed that diversity of picoeukaryotes in summer in the sub-Arctic White Sea corresponds to that ofthe other Arctic seas, such as the Beaufort and Norwegian Seas.
NEW PARAMECIUM SPECIES "CANDIDATUS PARAMECIUM OSSIPOVF Beliavskaia A., Kiselev A., Rautian M. Saint Petersburg State University [email protected] Among Paramecium species P. putrinum is one of the best identifiable. Most important discriminative features are small cell size (70-140 ^m), single big micronucleus (MI) and very special contractile vacuole (CV) represented as set of small vacuoles. We have studied several clones from different collecting sites that were characterized by all features mentioned above but with unusual habitus. Detailed analysis revealed several very specific characteristics ofthese clones. Usually the cells are bigger up to 120140 ^m. Their single MI has got "chromosomal" structure. Contractile vacuole differs from typical P. putrinum one. It has got short channels and is similar to CV of P. nephridiatum, or P. polycarium. Holospora-like bacterium found in P. putrinum do not infect "atypical" strains. Finally the sequence of cytochrome c oxidase subunit I gene has only 86% identity with the one of P. putrinum, which is much higher than difference between different P. putrinum syngens. Taking in account all above, we propose new species "Candidatus Paramecium ossipovi". Scientific research was performed at the Center for Culturing Collection ofMicroorganisms and Center for Molecular and Cell Technologies of Research park of St. Petersburg State University.
