Regional community assembly drivers and microbial environmental sources shaping bacterioplankton in an alpine lacustrine district (Pyrenees, Spain)

Abstract

SummaryMicrobial communities in natural ecosystems are subject to strong ecological rules. The study of local communities along a regional metacommunity can reveal patterns of community assembly, and disentangle the underlying ecological processes. In particular, we seek drivers of community assembly at the regional scale using a large lacustrine dataset (>300 lakes) along the geographical, limnological and physico‐chemical gradients in the Pyrenees. By using high throughput amplicon sequencing of the 16S rRNA gene, and inferring environmental sources of bacterial immigrants, we showed that surface aquatic bacterial assemblages were strongly influenced by terrestrial populations from soil, biofilms or sediments, and primarily selected by a pH‐alkalinity gradient. Indeed, source proportions explained 27% of the community variation, and chemistry 15% of the total variation, half of it shared with the sources. Major taxonomic groups such as Verrucomicrobia, Actinobacteria and Bacteroidetes showed higher aquatic affinities than Parcubacteria, Gammaproteobacteria, Alphaproteobacteria or Betaproteobacteria, which may be recruited and selected through different hydrographic habitats. A regional fingerprint was observed with lower alpha diversity and higher beta diversity in the central Pyrenees than in both ends. We suggest an ecological succession process, likely influenced by complex interactions of environmental source dispersal and environmental filtering along the mountain range geography.

Recent Differentiation of Aquatic Bacterial Communities in a Hydrological System in the Cuatro Ciénegas Basin, After a Natural Perturbation

“…For instance, the establishment of bacterial communities in beech tree holes seems to be governed by functional redundancy and founders’ effect ( Pascual-García and Bell, 2020 ). In contrast, communities from oligotrophic lakes in the Pyrenees have shown to be influenced by the interactions between environment and the community as well as migration processes, being environmental filtering a strong force ( Ortiz-Álvarez et al, 2020 ). Therefore, both the Grinnellian and Eltonian niches are relevant for the establishment of the lake microbial communities.…”

Bacteria in the lakes of the Tibetan Plateau and polar regions

“…Regional-scale comparative studies on lake bacterial communities are important in providing the understanding of basic questions of aquatic microbial ecology, such as how communities vary across spatial scales and environmental gradients. Several recent studies have shown a very important effect of local environmental conditions such as pH ( Ortiz-Álvarez et al, 2020) and salinity (Logares et al, 2013), and hydrographic factors such as water residence time and connectivity (Niño-García et al, 2016;Ruiz-González et al, 2015) in explaining spatial variations in lake bacterial communities at the regional scale. Despite the substantial efforts that have been made in disentangling the mechanisms shaping lake bacterial communities within relatively homogeneous regions, there have been few studies focus on the possible diverse response of lake bacteria to climate change between regions that have different regional climates and geomorphological conditions (Daniel et al, 2016).…”

Bacterioplankton Zonation Does Exist in High Elevation, Polymictic Lakes

“…Spatial analysis of microbial communities across different ecosystems has improved the detection of microbial hotspots and the testing of ecological assembly processes ( Gonzalez et al, 2012 ). Several variables have been identified in potentially shaping microbial communities in freshwater ecosystems such as the concentration of dissolved organic matter, pH, and hydrology ( Ruiz-González et al, 2015 ; Niño-García et al, 2016 ; Muscarella et al, 2019 ; Ortiz-Álvarez et al, 2020 ). However, when the vertical dimension is considered, one of the main environmental factors determining the variability in microbial composition is the existence of a thermal stratification that creates dispersal barriers for prokaryotes and non-motile phytoplankton ( Xiao et al, 2011 ; Peura et al, 2012 ; Yu et al, 2014 ; Cheng et al, 2020 ).…”