High-throughput sequencing of microbial eukaryotes in Lake Baikal reveals ecologically differentiated communities and novel evolutionary radiations.
We performed high-throughput 18S rDNA V9 region sequencing analyses of microeukaryote (protist) communities at seven sites with depths ranging from 0 to 1450 m in the southern part of Lake Baikal. We show that microeukaryotic diversity differed according to water column depth and sediment depth. Chrysophytes and perkinsids were diverse in subsurface samples, novel radiations of petalomonads and Ichthyobodo relatives were found in benthic samples, and a broad range of divergent OTUs were detected in deep subbenthic samples. Members of clades usually associated with marine habitats were also detected, including syndineans for the first time in freshwater systems. Fungal- and cercozoan-specific c. 1200 bp amplicon clone libraries also revealed many novel lineages in both planktonic and sediment samples at all depths, a novel radiation of aphelids in shallower benthic samples, and partitioning of sarcomonad lineages in shallow vs deep benthic samples. Putative parasitic lineages accounted for 12.4% of overall reads, including a novel radiation of Ichthyobodo (fish parasite) relatives. Micrometazoans were also analysed, including crustaceans, rotifers and nematodes. The deepest (>1000 m) subsurface sediment samples harboured some highly divergent sequence types, including heterotrophic flagellates, parasites, putative metazoans and sequences likely representing organisms originating from higher up in the water column.
['Yi|Zhenzhen|Z|', 'Berney|Cedric|C|', 'Hartikainen|Hanna|H|', 'Mahamdallie|Shazia|S|', 'Gardner|Michelle|M|', 'Boenigk|Jens|J|', 'Cavalier-Smith|Thomas|T|', 'Bass|David|D|']
D000818:Animals D044822:Biodiversity D005075:Biological Evolution D044523:Chrysophyta D003445:Crustacea D017753:Ecosystem D005658:Fungi D019015:Geologic Sediments D059014:High-Throughput Nucleotide Sequencing D060106:Lakes D009348:Nematoda D010802:Phylogeny D010933:Plankton D012337:RNA, Ribosomal, 18S D012403:Rotifera
Lake Baikal 18S rDNA microeukaryote depth Cercozoa fungi