Selective Pressure Influences Inter-Biome Dispersal in the Assembly of Saline Microbial Communities.

Selection and dispersal are the primary processes influencing community assembly at both global and regional scales. Although the effectiveness of dispersal is often examined within the same biome, microscopic organisms demonstrate the capability to colonise and thrive across different biomes. In this study, we evaluated the relationship between (i) aquatic, (ii) sedimentary and (iii) aerial microbial communities, and how local selective pressures influence the potential impact of inter-biome dispersal, focusing on the salinity gradient stress over time in ephemeral saline lakes.

Understanding stochastic and deterministic assembly processes in microbial communities along temporal, spatial and environmental scales.

Identifying the main drivers of community assembly remains an open fundamental question in ecology. Dispersal processes introduce randomness in community composition while selection for particular environments creates predictable assemblages. However, the interaction between selection and dispersal processes is still poorly understood.

Absence of stress-promoted facilitation coupled with a competition decrease in the microbiome of ephemeral saline lakes.

Salinity fluctuations constitute a well-known high stress factor strongly shaping global biological distributions and abundances. However, there is a knowledge gap regarding how increasing saline stress affects microbial biological interactions. We applied the combination of a probabilistic method for estimating significant co-occurrences/exclusions and a conceptual framework for filtering out associations potentially linked to environmental and/or spatial factors, in a series of connected ephemeral (hyper) saline lakes.

Ecological and Metabolic Thresholds in the Bacterial, Protist, and Fungal Microbiome of Ephemeral Saline Lakes (Monegros Desert, Spain).

We studied the 16S and 18S rRNA genes of the bacterial, protist, and fungal microbiomes of 131 samples collected in 14 ephemeral small inland lakes located in the endorheic area of the Monegros Desert (NE Spain). The sampling covered different temporal flooding/desiccation cycles that created natural salinity gradients between 0.1% (w/v) and salt saturation.

Dynamics and ecological distributions of the Archaea microbiome from inland saline lakes (Monegros Desert, Spain).

We characterized the rich Archaea microbiome of shallow inland lakes (Monegros Desert, NE Spain) by 16S rRNA gene tag sequencing covering a wide salinity range (0.1%-40% w/v) along 3 years. Up to 990 operational taxonomic units (OTUs; >97% identity) were detected allocated in 14 major archaeal phyla and heterogeneously distributed along the salt gradient.

A Randomized Trait Community Clustering approach to unveil consistent environmental thresholds in community assembly.

Similarities and differences of phenotypes within local co-occurring species hold the key to inferring the contribution of stochastic or deterministic processes in community assembly. Developing both phylogenetic-based and trait-based quantitative methods to unravel these processes is a major aim in community ecology. We developed a trait-based approach that: (i) assesses if a community trait clustering pattern is related to increasing environmental constraints along a gradient; and (ii) determines quantitative thresholds for an environmental variable along a gradient to interpret changes in prevailing community assembly drivers.

Microbial composition, potential functional roles and genetic novelty in gypsum-rich and hypersaline soils of Monegros and Gallocanta (Spain).

Soil microbial communities (both Bacteria and Archaea) were studied after 16S rRNA genes massive sequencing in two hypersaline and gypsum-rich contrasted sites located in NE Spain. Soil microbial communities were also locally analysed according to environmental variables, including geological, physico-chemical, biogeochemically, and climatic data. Typical soil characteristics, climate data, and plant composition clearly split the two sites and major differences among the microbial communities for the areas were initially expected.