Abstract
Rare biosphere represents the majority of Earth's biodiversity and performs vital ecological functions, yet little is known about its biogeographical patterns and community assembly processes in terrestrial ecosystems. Herein, we investigated the community composition and phylogeny of rare (relative abundance <0.1%) and abundant (>1%) bacteria in dryland grassland soils on the Tibetan Plateau. Results revealed similar biogeographical patterns of rare and abundant bacteria at both compositional and phylogenetic levels, but rare subcommunity was more heavily influenced by stochasticity (72%) than the abundant (57%). The compositional variation of rare bacteria was less explained by environmental factors (41%) than that of the abundant (80%), while the phylogeny of rare bacteria (36%) was more explained than that of the abundant (29%). The phylogeny of rare bacteria was equally explained by local factors (soil and vegetation) and geospatial distance (11.5% and 11.9% respectively), while that of the abundant was more explained by geospatial distance (22.1%) than local factors (11.3%). Furthermore, a substantially tighter connection between the community phylogeny and composition was observed in rare (R2 = 0.65) than in abundant bacteria (R2 = 0.08). Our study provides novel insights into the assembly processes and biographical patterns of rare and abundant bacteria in dryland soils.
Highlights
The bacteria in low abundance represent the majority of Earth’s biodiversity (Naeem and Li, 1997), and these rare bacteria contain an enormous pool of genetic novelty (Vigneron et al, 2018)
The community composition of rare bacteria was more strongly influenced by local environmental factors, while that of abundant bacteria was predominately explained by geospatial factors (Liu et al, 2015; Mo et al, 2018)
Rare bacteria comprised 87.7% of the total bacterial richness (6,923 operational taxonomic units (OTUs)), but their total relative abundance accounted for only 10.1% of the entire community
Summary
The bacteria in low abundance represent the majority of Earth’s biodiversity (Naeem and Li, 1997), and these rare bacteria contain an enormous pool of genetic novelty (Vigneron et al, 2018). Rare bacteria are responsible for nitrogen and carbon assimilation in freshwater lakes (Montoya et al, 2004; Hua et al, 2015; Hausmann et al, 2016), they enhance plant defence against aphids (Hol et al, 2010), and provide insurance during ecological restoration (Gibbons et al, 2013; Mouillot et al, 2013; Jousset et al, 2017) Variation in these low abundance, but functional important microorganisms could cause substantial consequences on an ecosystem. The relative importance of local environmental factors and geospatial factors on the biogeography of rare and abundant bacteria could be different from that identified in aquatic ecosystems To test these hypotheses, the bacterial community structure was investigated using DNA-based amplicon sequencing of 16S rRNA gene, and both the community Bray-Curtis compositional dissimilarity and βMNTD phylogenetic distance were calculated. These metrics were used to compare the community compositions and phylogenies of rare and abundant bacteria along a 1200 km grassland transect on the Tibetan Plateau
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
