02380nas a2200253 4500008004100000245012200041210006900163260001200232300000900244490000600253520157500259653001501834653002701849653002401876653001901900653001601919653001901935653002701954100002501981700002902006700002602035700002102061856004402082 2021 eng d00aPhagotrophic protists and their associates: Evidence for preferential grazing in an abiotically driven soil ecosystem0 aPhagotrophic protists and their associates Evidence for preferen c08/2021 a15550 v93 a

The complex relationship between ecosystem function and soil food web structure is governed by species interactions, many of which remain unmapped. Phagotrophic protists structure soil food webs by grazing the microbiome, yet their involvement in intraguild competition, susceptibility to predator diversity, and grazing preferences are only vaguely known. These species-dependent interactions are contextualized by adjacent biotic and abiotic processes, and thus obfuscated by typically high soil biodiversity. Such questions may be investigated in the McMurdo Dry Valleys (MDV) of Antarctica because the physical environment strongly filters biodiversity and simplifies the influence of abiotic factors. To detect the potential interactions in the MDV, we analyzed the co-occurrence among shotgun metagenome sequences for associations suggestive of intraguild competition, predation, and preferential grazing. In order to control for confounding abiotic drivers, we tested co-occurrence patterns against various climatic and edaphic factors. Non-random co-occurrence between phagotrophic protists and other soil fauna was biotically driven, but we found no support for competition or predation. However, protists predominately associated with Proteobacteria and avoided Actinobacteria, suggesting grazing preferences were modulated by bacterial cell-wall structure and growth rate. Our study provides a critical starting-point for mapping protist interactions in native soils and highlights key trends for future targeted molecular and culture-based approaches.

10aAntarctica10aco-occurrence networks10aMcMurdo Dry Valleys10aRhogostoma sp.10aSandona sp.10asoil food webs10avariation partitioning1 aThompson, Andrew, R.1 aRoth-Monzón, Andrea, J.1 aAanderud, Zachary, T.1 aAdams, Byron, J. uhttps://www.mdpi.com/2076-2607/9/8/155502687nas a2200205 4500008004100000022001400041245013600055210006900191260001200260300001400272490000700286520195800293653004302251653002302294653002102317653003102338653002202369100002502391856006502416 2021 eng d a0722-406000aPhagotrophic protists (protozoa) in Antarctic terrestrial ecosystems: Diversity, distribution, ecology, and best research practices0 aPhagotrophic protists protozoa in Antarctic terrestrial ecosyste c08/2021 a1467-14840 v443 a

Phagotrophic protists (formerly protozoa) are a highly diverse, polyphyletic grouping of generally unicellular, heterotrophic eukaryotes that are key regulators of the soil microbiome. The biodiversity and ecology of soil phagotrophic protists are still largely uncharacterized, especially in the Antarctic, which possesses some of the harshest terrestrial environments known and potentially many physiologically unique and scientifically interesting species. Antarctic soil systems are also highly limited in terms of moisture, temperature, and carbon, and the resulting reduced biological complexity can facilitate fine-tuned investigation of the drivers and functioning of microbial communities. To facilitate and encourage future research into protist biodiversity and ecology, especially in context of the broader functioning of Antarctic terrestrial communities, I review the biodiversity, distribution, and ecology of Antarctic soil phagotrophic protists. Biodiversity appears to be highly structured by region and taxonomic group, with the Antarctic Peninsula having the highest taxonomic diversity and ciliates (Ciliophora) being the most diverse taxonomic group. However, richness estimates are likely skewed by disproportionate sampling (over half of the studies are from the peninsula), habitat type bias (predominately moss-associated soils), investigator bias (toward ciliates and the testate amoeba morphogroup), and methodological approach (toward cultivation and morphological identification). To remedy these biases, a standardized methodology using both morphological and molecular identification and increased emphasis on microflagellate and naked amoeba morphogroups is needed. Additionally, future research should transition away from biodiversity survey studies to dedicated ecological studies that emphasize the function, ecophysiology, endemicity, dispersal, and impact of abiotic drivers beyond moisture and temperature.

10aabiotic drivers of protist communities10aAntarctic protozoa10aCorythion dubium10aphagotrophic soil protists10aprotist diversity1 aThompson, Andrew, R. uhttps://link.springer.com/article/10.1007/s00300-021-02896-301897nas a2200133 4500008004100000245008000041210006900121260001200190520131700202100002501519700002301544700001701567856017901584 2019 eng d00aProvisional checklist of terrestrial heterotrophic protists from Antarctica0 aProvisional checklist of terrestrial heterotrophic protists from c11/20193 a

Heterotrophic soil protists encompass lineages that are both evolutionarily ancient and highly diverse, providing an untapped wealth of scientific insight. Yet the diversity of free-living heterotrophic terrestrial protists is still largely unknown. To contribute to our understanding of this diversity, we present a checklist of heterotrophic protists currently reported from terrestrial Antarctica, for which no comprehensive evaluation currently exists. As a polar continent, Antarctica is especially susceptible to rising temperatures caused by anthropogenic climate change. Establishing a baseline for future conservation efforts of Antarctic protists is therefore important. We performed a literature search and found 236 taxa identified to species and an additional 303 taxa identified to higher taxonomic levels in 54 studies spanning over 100 years of research. Isolated by distance, climate and the circumpolar vortex, Antarctica is the most extreme continent on Earth: it is not unreasonable to think that it may host physiologically and evolutionarily unique species of protists, yet currently most species discovered in Antarctica are considered cosmopolitan. Additional sampling of the more extreme intra-continental zones will probably result in the discovery of more novel and unique taxa.

1 aThompson, Andrew, R.1 aPowell, Gareth, S.1 aAdams, Byron uhttps://www.cambridge.org/core/journals/antarctic-science/article/provisional-checklist-of-terrestrial-heterotrophic-protists-from-antarctica/DC08D89ABDC5AF2CC83E38B1C6F1F78C