Infrequent marine–freshwater transitions in the microbial world

Logares, Ramiro; Bråte, Jon; Bertilsson, Stefan; Clasen, J.; Shalchian-Tabrizi, Kamran; Rengefors, Karin

doi:10.1016/j.tim.2009.05.010

Cited by 317 publications

(339 citation statements)

References 82 publications

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“…Overall, our results on the putative parasites of Perkinsea show only a few successful crosscolonization events between marine and fresh waters during the evolutionary diversification of this group, implying that the biogeochemical differences between marine and fresh waters represent a strong barrier against cross-colonizations, concordant with recent results from other groups of free-living protists (Logares et al, 2009). …”

Section: Marine-freshwater Colonizationssupporting

confidence: 90%

“…Recent studies indicate that saline and fresh waters contain phylogenetically distinct taxa, implying that cross-colonizations between these environments have been rare during the evolution of most eukaryotic and prokaryotic groups (reviewed in Logares et al, 2009). As parasites usually need to be adapted to both the host and the extracellular environment, their spatiotemporal distribution patterns may therefore differ from that of free-living protists.…”

Section: Introductionmentioning

confidence: 99%

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Freshwater Perkinsea and marine-freshwater colonizations revealed by pyrosequencing and phylogeny of environmental rDNA

et al. 2010

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Protist parasites are ecologically important, as they can have great impact on host population dynamics and functioning of entire ecosystems. Nevertheless, little is known about their prevalence in aquatic habitats. Here, we investigate the diversity and distributional patterns of the protist parasites Perkinsus and Parvilucifera (Perkinsea). Our approach included 454 pyrosequencing of the 18S rDNA gene obtained from a high-altitude lake (Lake Finsevatn, Norway) and phylogenetic analyses of all publicly available sequences related to Perkinsea. The applied PCR primers target a 450 bp region that encompass the variable V4 region of the 18S rDNA gene and have been optimized for the Titanium upgrade of the 454 technology. Nearly 5000 sequences longer than 150 bp were recovered from nearly all eukaryotic supergroups, and of those, 13 unique sequences were affiliated to Perkinsea. Thus, our new strategy for 454 amplicon sequencing was able to recover a large diversity of distantly related eukaryotes and previously unknown species of Perkinsea. In addition, we identified 40 Perkinsea sequences in GenBank generated by other recent diversity surveys. Importantly, phylogenetic analyses of these sequences identified 17 habitat-specific marine and freshwater clades . Hence, only a few successful transitions between these habitats have taken place over the entire history of Perkinsea, suggesting that the boundary between marine and fresh waters may constitute a barrier to cross-colonizations for intracellular parasites.

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Section: Marine-freshwater Colonizationssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Freshwater Perkinsea and marine-freshwater colonizations revealed by pyrosequencing and phylogeny of environmental rDNA

et al. 2010

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“…Thus, the spatial distribution of MAST-4 seemed to be mainly controlled by contemporary environmental factors with a null or low degree of provincialism. Other abiotic factors that are known to be important in defining microbial community composition, such as salinity (Logares et al, 2009) and sampling depth (Winter et al, 2008), were important within each of the defined temperature group.…”

Section: Discussionmentioning

confidence: 99%

Biogeography of the uncultured marine picoeukaryote MAST-4: temperature-driven distribution patterns

et al. 2013

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The MAST-4 (marine stramenopile group 4) is a widespread uncultured picoeukaryote that makes up an important fraction of marine heterotrophic flagellates. This group has low genetic divergence and is composed of a small number of putative species. We combined ARISA (automated ribosomal intergenic spacer analysis) and ITS (Internal Transcribed Spacer) clone libraries to study the biogeography of this marine protist, examining both spatial and temporal trends in MAST-4 assemblages and associated environmental factors. The most represented MAST-4 clades appeared adapted to different temperature ranges, and their distributions did not suggest clear geographical barriers for dispersal. Distant samples sharing the same temperature had very similar assemblages, especially in cold temperatures, where only one clade, E1, dominated. The most highly represented clades, A and E1, showed very little differentiation between populations from distant geographical regions. Within a single site, temporal variation also followed patterns governed by temperature. Our results contribute to the general discussion on microbial biogeography by showing strong environmental selection for some picoeukaryotes in the marine environment.

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“…A possible explanation for the differences observed for freshwater and saline environments regarding the assembly mechanisms of the mixed communities composition and the importance of freshwater specialists versus generalists could be that saline conditions are more ancestral (Logares et al, 2009), and that moderately saline conditions, like the ones in the salinity incubations of our experiment, are closer to the ionic conditions within cells (Kü ltz 2001;Cossins et al, 2011). Low-conductivity environments, such as the freshwater incubations, represent hypoosmotic conditions that require a greater extent of specific adaptations from bacteria.…”

Section: Fate Of Dispersed Bacterial Communitiesmentioning

confidence: 99%

Mechanisms determining the fate of dispersed bacterial communities in new environments

2012

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Recent work has shown that dispersal has an important role in shaping microbial communities. However, little is known about how dispersed bacteria cope with new environmental conditions and how they compete with local resident communities. To test this, we implemented two full-factorial transplant experiments with bacterial communities originating from two sources (freshwater or saline water), which were incubated, separately or in mixes, under both environmental conditions. Thus, we were able to separately test for the effects of the new environment with and without interactions with local communities. We determined community composition using 454-pyrosequencing of bacterial 16S rRNA to specifically target the active fraction of the communities, and measured several functional parameters. In absence of a local resident community, the net functional response was mainly affected by the environmental conditions, suggesting successful functional adaptation to the new environmental conditions. Community composition was influenced both by the source and the incubation environment, suggesting simultaneous effects of species sorting and functional plasticity. In presence of a local resident community, functional parameters were higher compared with those expected from proportional mixes of the unmixed communities in three out of four cases. This was accompanied by an increase in the relative abundance of generalists, suggesting that competitive interactions among local and immigrant taxa could explain the observed 'functional overachievement'. In summary, our results suggest that environmental filtering, functional plasticity and competition are all important mechanisms influencing the fate of dispersed communities.

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Infrequent marine–freshwater transitions in the microbial world

Cited by 317 publications

References 82 publications

Freshwater Perkinsea and marine-freshwater colonizations revealed by pyrosequencing and phylogeny of environmental rDNA

Freshwater Perkinsea and marine-freshwater colonizations revealed by pyrosequencing and phylogeny of environmental rDNA

Biogeography of the uncultured marine picoeukaryote MAST-4: temperature-driven distribution patterns

Mechanisms determining the fate of dispersed bacterial communities in new environments

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