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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
