Abstract
The biogeographical distribution of soil bacterial communities has been widely investigated. However, there has been little study of the biogeography of soil archaeal communities on a regional scale. Here, using high-throughput sequencing, we characterized the archaeal communities of 94 soil samples across the eastern Tibetan Plateau. Thaumarchaeota was the predominant archael phylum in all the soils, and Halobacteria was dominant only in dry soils. Archaeal community composition was significantly correlated with soil moisture content and C:N ratio, and archaeal phylotype richness was negatively correlated with soil moisture content (r = −0.47, P < 0.01). Spatial distance, a potential measure of the legacy effect of evolutionary and dispersal factors, was less important than measured environmental factors in determining the broad scale archaeal community pattern. These results indicate that soil moisture and C:N ratio are the key factors structuring soil archaeal communities on the eastern Tibetan Plateau. Our findings suggest that archaeal communities have adjusted their distributions rapidly enough to reach range equilibrium in relation to past environmental changes e.g. in water availability and soil nutrient status. This responsiveness may allow better prediction of future responses of soil archaea to environmental change in these sensitive ecosystems.
Highlights
Studying the distribution of soil microbial communities across the space and time may give important indications of the processes that dominate microbial ecology[1]
Regardless of the community metric studied, the archaeal phylotype richness, measured as Operational Taxonomic Unit (OTU) (>= 97% similarity), was negatively correlated with soil moisture(r = −0 .47, p < 0.01) (Table 1). Other soil characteristics, such as total nitrogen, total carbon, soil organic carbon, dissolved total nitrogen, NH4+-N and NO3−-N were negatively correlated with archaeal OTU richness (Table 1). These results suggest that soil moisture could be a driving factor for soil archaeal community composition and phylotype richness across the eastern Tibetan Plateau
We found that Thaumarchaeota was the dominant archael phylum in all three main vegetation types across the >900 km study area, while the relative abundance of Halobacteria was the highest in the desert steppe soils (Fig. 1)
Summary
Studying the distribution of soil microbial communities across the space and time may give important indications of the processes that dominate microbial ecology[1]. Various studies have been conducted to compare patterns in microbial distributions to those commonly observed for animal and plant taxa[2,3] These have included studies of soil microbial communities across North America[4], the Arctic[5], Britain[6] and the western Tibetan Plateau[7]. Tripathi et al.[22] compared soil archaeal communities in moist climates in tropical and temperate eastern Asia, and found evidence that environment in terms of both climate and soil pH has a strong influence on archaeal community structure These latter studies indicated that contemporary environmental factors, rather than dispersal lag and local evolution, are more important in shaping the soil archaeal community structure. We set out to investigate the following questions: 1) What are the dominant archaeal taxa in Tibetan soils? 2) How is the archaeal community distributed across the Tibetan Plateau soils? Can variation in archaeal community be explained in terms of environment alone, without invoking distance and dispersal history as a part of the explanation?
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