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<p>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.</p>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/2076-2607/9/8/155502038nas a2200205   4500008004100000245010100041210006900142260001200211520136000223653001501583653001801598653002201616653001701638653001301655653002201668100002501690700001901715700001701734856008101751       2020                        eng d00aShotgun metagenomics reveal a diverse assemblage of protists in a model Antarctic soil ecosystem0 aShotgun metagenomics reveal a diverse assemblage of protists in   c08/20203 a<p>The soils of the McMurdo Dry Valleys (MDV) of Antarctica are established models for understanding fundamental processes in soil ecosystem functioning (e.g. ecological tipping points, community structuring, and nutrient cycling) because the extreme physical environment drastically reduces biodiversity and ecological complexity. Understanding the functioning of MDV soils requires in‐depth knowledge of the diversity of MDV soil species. Protists, which contribute significantly to soil ecosystem functioning worldwide, remain poorly characterized in the MDV. To better assess the diversity of MDV protists, we performed shotgun metagenomics on 18 sites representing a variety of landscape features and edaphic variables. Our results show MDV soil protists are diverse at both the genus (155 of 281 eukaryote genera) and family (120) levels, but comprise only 6% of eukaryotic reads. Protists are structured by moisture, total N, and distance from the local coast, and possess limited richness in arid (&lt;5% moisture) and at high elevation sites, known drivers of communities in the MDV. High relative diversity and broad distribution of protists in our study promotes these organisms as key members of MDV soil microbiomes and the MDV as a useful system for understanding the contribution of soil protists to the structure of soil microbiomes.</p>10aAntarctica10aextremophiles10afunctional groups10ametagenomics10aprotozoa10asoil microbiology1 aThompson, Andrew, R.1 aGeisen, Stefan1 aAdams, Byron  uhttps://sfamjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1462-2920.15198