Contrasting early successional dynamics of bacterial and fungal communities in recently deglaciated soils of the maritime Antarctic

Abstract

Although microorganisms are the very first colonizers of recently deglaciated soils even prior to plant colonization, the drivers and patterns of microbial community succession at early‐successional stages remain poorly understood. The successional dynamics and assembly processes of bacterial and fungal communities were compared on a glacier foreland in the maritime Antarctic across the ~10‐year soil‐age gradient from bare soil to sparsely vegetated area. Bacterial communities shifted more rapidly than fungal communities in response to glacial retreat; species turnover (primarily the transition from glacier‐ to soil‐favouring taxa) contributed greatly to bacterial beta diversity, but this pattern was less clear in fungi. Bacterial communities underwent more predictable (more deterministic) changes along the soil‐age gradient, with compositional changes paralleling the direction of changes in soil physicochemical properties following deglaciation. In contrast, the compositional shift in fungal communities was less associated with changes in deglaciation‐induced changes in soil geochemistry and most fungal taxa displayed mosaic abundance distribution across the landscape, suggesting that the successional dynamics of fungal communities are largely governed by stochastic processes. A co‐occurrence network analysis revealed that biotic interactions between bacteria and fungi are very weak in early succession. Taken together, these results collectively suggest that bacterial and fungal communities in recently deglaciated soils are largely decoupled from each other during succession and exert very divergent trajectories of succession and assembly under different selective forces.

A poisoned apple: First insights into community assembly and networks of the fungal pathobiome of healthy-looking senescing leaves of temperate trees in mixed forest ecosystem

“…To quantify the relative proportion of deterministic and stochastic processes in community assembly, the phylogenetic normalized stochasticity ratio (pNST) and beta nearest taxon indices (βNTI) based on the null model theory were calculated using ‘iCAMP’ package in R ( Stegen et al., 2013 ; Ning et al., 2020 ; Sun et al., 2021 ). The fungal ITS gene sequences obtained by Illumina sequencing have been recently used to construct the phylogenetic and null model analyses for determining the assembly processes of fungal communities ( Gyeong et al., 2021 ; Wang et al., 2022 ; Zhao et al., 2022 ). Although 18S nuclear ribosomal small subunit rRNA gene (SSU) is more appropriate and commonly applied to construct the phylogenetic tree of fungi than the ITS gene, it has lower hypervariable domains in fungi ( Schoch et al., 2012 ).…”

Responses of soil micro-eukaryotic communities to decadal drainage in a Siberian wet tussock tundra

“…Despite these efforts, certain ITS2 sequences assigned to 'unclassified fungi' actually did not represent fungi. Particularly with datasets from polar regions the number of reference sequences available in public databases is rather limited (Gyeong et al, 2021). To refine the exclusion of non-fungal ITS2 sequences, we performed additional BLASTN searches against the NCBI nucleotide collection (nr/nt) (downloaded Dec 2022) for those ITS2 sequences categorized as 'unclassified fungi' by the UNITE database.…”

UAVs for Science in Antarctica

“…To examine poorly understood linkages of microbial communities between lake ecosystems and surrounding soils and glaciers, as to provide the context of the fieldwork area and discriminate different classes (moraines, glacier/lake ridge, ice patch within lake) and to guide the sampling of microbial communities in cryoconite holes, UAV surveys developed in Lake Untersee Oasis in Queen Maud Land, East Antarctica played an important role as reported by Weisleitmer et al (2020) [62]. The analysis of soils in a recent glacier retreat front was guided by UAV surveys that allowed reconstructing successional stages with very detail, as reported by Gyeong et al (2021) [63]. The role played by the ornithogenic factor in soil formation in Antarctica was analysed by Abakumov et al (2021) [64] on field and laboratory data on soil features and also on UAV imagery to help identifying different soil areas and field routes.…”