Biology subjects

de los Rios, A.

Publications and source records attributed to de los Rios, A..

3 recordsLinked to original sources

bioRxiv2025

Aridity drives global convergence of desert microbiomes and biogeochemical activities

Deserts cover a third of the worlds surface, supporting unique biomes and ecosystem services. Yet, we lack a comprehensive assessment of what defines and drives the microbial communities that dominate life in these regions. Here, we conducted a standardized field survey in contrasting cold, hot, and polar deserts across the seven continents, and observed geographically distant deserts share similar structure, function, and activities. Desert communities are dominated by genomically streamlined Actinobacteriota and Chloroflexota, and compared with non-desert soils, are significantly enriched with stress tolerance genes, mobile genetic elements, and antiviral strategies, revealing previously unknown ecological and evolutionary dynamics. Metabolically, these communities exhibit reduced capacity for carbohydrate and protein degradation, and instead are enriched for chemosynthetic carbon fixation, continuous energy harvesting using atmospheric trace gases and sunlight, and energy reserve biosynthesis. All sampled soils mediated respiration, trace gas oxidation, and carbon fixation, with detectable activity even in hyper-arid Atacama and Antarctic soils at the margins of life. Driver analyses identified aridity as the primary overriding driver of the microbial communities and biogeochemical activities. Collectively, these findings suggest that aridity selects for metabolically self-sufficient taxa capable of continuously meeting energy and carbon needs independently of vegetation-derived inputs, while enduring physicochemical stressors and potentially elevated viral pressure. These new insights are integral to forecast the future of soils amid increasing desertification. Significance statementDesert soils occupy a vast and expanding portion of Earth, yet what defines and governs their dominant microbial life remains incompletely defined. By assessing the composition, capabilities, and activities of microbial communities across deserts on all seven continents, we identify unifying signatures of life under extreme water limitation. We show microbial communities are highly self-sufficient, capable of acquiring energy and carbon even where plant inputs are minimal. This planetary-scale understanding of the desert microbiome has important ramifications for forecasting potential shifts of microbial communities and the services they provide as desertification intensifies.

microbiology↗

bioRxiv2025

Metabolically flexible microorganisms rapidly establish glacial foreland ecosystems

An overriding question in ecology is how new ecosystems form. This question can be tested by studying colonisation of environments with little to no pre-existing life. Here, we investigated the functional basis of microbial colonisation in the forelands of a maritime Antarctic and an alpine Swiss retreating glacier, by integrating quantitative ecology, genome-resolved metagenomics, and biogeochemical measurements. Habitat generalists and opportunists rapidly colonize both forelands and persist across soil depth and decadal chronosequences that serve as proxies for temporal community dynamics. These microbes are metabolically flexible chemotrophic aerobes that overcome oligotrophic conditions by using both organic and inorganic compounds, including atmospheric trace gases and sulfur substrates, for energy and carbon acquisition. They co-exist with metabolically flexible early-colonising opportunists and metabolically restricted later-colonising specialists, including photosynthetic Cyanobacteria, ammonia-oxidising archaea, and obligate predatory and symbiotic bacteria, that exhibit narrower habitat distributions. Analysis of 589 species-level metagenome-assembled genomes reveals early colonisation both by generalists and opportunists is strongly associated with metabolic flexibility. Field- and laboratory-based biogeochemical measurements reveal the activity of metabolically flexible microbes rapidly commenced in the forelands. Altogether, these findings suggest primary succession in glacial foreland soils is driven by self-sufficient metabolically flexible bacteria that mediate chemosynthetic primary production and likely provide a more hospitable soil environment for subsequent colonisation.

microbiology↗

bioRxiv2025

Towards a monograph of marine Verrucariaceae in Southern South America and maritime Antarctica: Integrative taxonomy reveals a previously unknown diversity

The family of predominantly lichen-forming Verrucariaceae, contains several lineages that have adapted to live in the stressful conditions of the intertidal and supralittoral zones of rocky seashores in both hemispheres. The marine Verrucariaceae has been the subject of several systematic and taxonomic studies over the past few decades, although these studies have primarily concentrated on groups from the northern hemisphere. This study aims to address the paucity of taxonomic studies in the southern hemisphere by examining a substantial number of specimens collected in Southern South America and maritime Antarctica over the past two decades by the authors. We opted for an integrative taxonomic approach that joins the characterization and measurement of morpho-anatomical characters, coupled together with molecular barcoding to produce species delimitations to overcome the difficulties derived by the scarcity of taxonomic characters and the high plasticity of those characters. We barcoded a total of 301 specimens using the universal barcode un fungi (nrITS) and used single-locus species delimitation algorithms (ASAP, PTP, GMYC) to produce candidate species hypothesis that were corroborated with the morphological data. Our findings indicate that the taxonomic diversity of the Southern Hemisphere Verrucaria marina group has been significantly underestimated in previous studies. A total of 27 species were found in the region, 21 of which represent new taxa for science. Thorough descriptions together with illustrations showing the main characters of the species are provided for each taxon. In addition, we explored the systematics of the new taxa. We reconstructed the phylogenetic relationships of the family based on on six molecular markers (ITS, mcm7, nrSSU, nrLSU, mtSSU, RPB1). Our results showed that marine Verrucariaceae from the studied area belong to two distinct and non-related clades. A small group of species were related to the northern hemisphere species Turgidosculum ulvae. The second and more numerous group, which included the characteristic species Mastodia tessellata for a clade sister to the European genus Verrucariopsis. The systematic consequences of our findings are discussed. None of the previously reported species from the northern hemisphere and considered bipolar were found during our study.

genetics↗