“…Fieldwork was conducted in the PCMs (East Antarctica; figure 1 a ) from 26 November 2011 to 21 January 2012 at Mount Menzies (MM), Mawson Escarpment (ME) and Lake Terrasovoje (LT), and is described in detail elsewhere [26]. A total of 136 samples were considered for this study, with 20 from MM, 64 from ME and 52 from LT.
Figure 1.Sampling locations yielding invertebrate phylotypes in the Prince Charles Mountains, East Antarctica.…”
Section: Methodsmentioning
confidence: 99%
“…After filtering the raw sequence data based on quality scores ( Phred score 19), and removal of chimeras in a de novo approach employing U search v. 6.1. [44], phylotype clustering was performed as described in Czechowski et al [26] and taxonomy assigned using the Silva database v. 119 [45]. To allow abundance correction using the CSS algorithm [46] instead of depreciated resampling approaches [47], stringent filtering removed all phylotypes covered by less than 100 sequences and all samples with less than 1000 reads, analogous to, but more stringent than, other metabarcoding studies [48,49].…”
The potential impact of environmental change on terrestrial Antarctic ecosystems can be explored by inspecting biodiversity patterns across large-scale gradients. Unfortunately, morphology-based surveys of Antarctic invertebrates are time-consuming and limited by the cryptic nature of many taxa. We used biodiversity information derived from high-throughput sequencing (HTS) to elucidate the relationship between soil properties and invertebrate biodiversity in the Prince Charles Mountains, East Antarctica. Across 136 analysed soil samples collected from Mount Menzies, Mawson Escarpment and Lake Terrasovoje, we found invertebrate distribution in the Prince Charles Mountains significantly influenced by soil salinity and/or sulfur content. Phyla Tardigrada and Arachnida occurred predominantly in low-salinity substrates with abundant nutrients, whereas Bdelloidea (Rotifera) and Chromadorea (Nematoda) were more common in highly saline substrates. A significant correlation between invertebrate occurrence, soil salinity and time since deglaciation indicates that terrain age indirectly influences Antarctic terrestrial biodiversity, with more recently deglaciated areas supporting greater diversity. Our study demonstrates the value of HTS metabarcoding to investigate environmental constraints on inconspicuous soil biodiversity across large spatial scales.
“…Fieldwork was conducted in the PCMs (East Antarctica; figure 1 a ) from 26 November 2011 to 21 January 2012 at Mount Menzies (MM), Mawson Escarpment (ME) and Lake Terrasovoje (LT), and is described in detail elsewhere [26]. A total of 136 samples were considered for this study, with 20 from MM, 64 from ME and 52 from LT.
Figure 1.Sampling locations yielding invertebrate phylotypes in the Prince Charles Mountains, East Antarctica.…”
Section: Methodsmentioning
confidence: 99%
“…After filtering the raw sequence data based on quality scores ( Phred score 19), and removal of chimeras in a de novo approach employing U search v. 6.1. [44], phylotype clustering was performed as described in Czechowski et al [26] and taxonomy assigned using the Silva database v. 119 [45]. To allow abundance correction using the CSS algorithm [46] instead of depreciated resampling approaches [47], stringent filtering removed all phylotypes covered by less than 100 sequences and all samples with less than 1000 reads, analogous to, but more stringent than, other metabarcoding studies [48,49].…”
The potential impact of environmental change on terrestrial Antarctic ecosystems can be explored by inspecting biodiversity patterns across large-scale gradients. Unfortunately, morphology-based surveys of Antarctic invertebrates are time-consuming and limited by the cryptic nature of many taxa. We used biodiversity information derived from high-throughput sequencing (HTS) to elucidate the relationship between soil properties and invertebrate biodiversity in the Prince Charles Mountains, East Antarctica. Across 136 analysed soil samples collected from Mount Menzies, Mawson Escarpment and Lake Terrasovoje, we found invertebrate distribution in the Prince Charles Mountains significantly influenced by soil salinity and/or sulfur content. Phyla Tardigrada and Arachnida occurred predominantly in low-salinity substrates with abundant nutrients, whereas Bdelloidea (Rotifera) and Chromadorea (Nematoda) were more common in highly saline substrates. A significant correlation between invertebrate occurrence, soil salinity and time since deglaciation indicates that terrain age indirectly influences Antarctic terrestrial biodiversity, with more recently deglaciated areas supporting greater diversity. Our study demonstrates the value of HTS metabarcoding to investigate environmental constraints on inconspicuous soil biodiversity across large spatial scales.
“…DNA extractions of Australian and Antarctic soils were performed at the South Australian Research and Development Institute (SARDI) using a method optimized for the retrieval of DNA from different soil types and the retrieval of invertebrates in agricultural ecosystems for plant pathogen detection [26,[36][37][38][39], that processes 400 g of starting material. Cross contamination during extraction was detected by measuring the concentration of blank extractions [26].…”
Section: Dna Extractionsmentioning
confidence: 99%
“…Cross contamination during extraction was detected by measuring the concentration of blank extractions [26]. DNA was stored at -20 °C (SARDI) and at -60 °C (University of Adelaide).…”
Section: Dna Extractionsmentioning
confidence: 99%
“…With such metabarcoding methods (sensu [21]), morphologically conserved species are rapidly distinguished in parallel from substrates such as soil, snow or water [22][23][24][25], using simple sampling procedures and laboratory workflows [23,26]. In Antarctica, HTS based metabarcoding studies have investigated viruses [27], bacteria [17,28,29] and predominantly unicellular, fungal or algal, eukaryotes [18,26,30]. Such metabarcoding studies could also be increasingly applied specifically to invertebrate taxa, and may there be particularly useful to provide broad taxonomic classification across large spatial distances (i.e.…”
taxonomy determination did not outperform metabarcoding approaches. Our study demonstrates how barcoding markers can be tested prior to their application to specific taxonomic groups, and that taxonomy fidelity of markers needs to be validated in relation to environment, taxa, and available reference information.
Keywords:environmental DNA, metataxonomic, mitochondrial cytochrome c oxidase I, COI, 18S rDNA, Illumina, 454, biodiversity survey
IntroductionBiodiversity information from Antarctic terrestrial habitats is important for estimating the effects of environmental change on Antarctic ecosystems [1,2], conservation management in light of increasing threats from nonindigenous invasive species [3], and investigations on the historic effect of glacial constraints on the evolution of Antarctic biotas over millions of years [4]. Undertaking such biodiversity research in terrestrial Antarctica is challenging due to the logistics of accessing remote locations in a harsh environment [5]. In recent years, biodiversity information for terrestrial Antarctic plant life has improved due to compilation of occurrence records from smaller-scale studies into easily accessible databases, and may in the future be easier to obtain through remote sensing technology [6,7]. However, the distribution and diversity of Antarctic invertebrates remains understudied [8,9] despite their important role in nutrient cycling and soil formation [10].Deficient biodiversity information for terrestrial Antarctic invertebrates is caused by the persistence of slow and inefficient survey methods. Antarctic springtails, mites, tardigrades, nematodes and rotifers are morphologically conserved, but still frequently analyzed with morphological approaches, requiring highly skilled taxonomists -time required to identify such invertebrates can be considered inversely proportional to their size [11][12][13][14]. Not reliant on morphological identification, DNA- Abstract: Biodiversity information from Antarctic terrestrial habitats helps conservation efforts, but the distribution and diversity particularly of microinvertebrates remains poorly understood. Springtails, mites, tardigrades, nematodes and rotifers are difficult to identify using morphological features, hence DNAbased metabarcoding methods are well suited for their study. We compared taxonomy assignments of a high throughput sequencing metabarcoding approach using one ribosomal DNA (18S rDNA) and one mitochondrial DNA (cytochrome c oxidase subunit I -COI) marker with morphological reference data. Specifically, we compared metabarcoding or morphological taxonomic assignments on multiple taxonomic levels in an artificial DNA blend containing Australian invertebrates, and in seven extracts of Antarctic soils containing known micro-faunal taxa. Avoiding arbitrary application of metabarcoding analysis parameters, we calibrated those parameters with metabarcoding data from non-Antarctic soils. Metabarcoding approaches employing 18S rDNA and COI markers enabled detection of small and cryptic Antarctic i...
The ecological drivers of soil biodiversity in the Southern Hemisphere remain underexplored. Here, in a continental survey comprising 647 sites, across 58 degrees of latitude between tropical Australia and Antarctica, we evaluated the major ecological patterns in soil biodiversity and relative abundance of ecological clusters within a co-occurrence network of soil bacteria, archaea and eukaryotes. Six major ecological clusters (modules) of co-occurring soil taxa were identified. These clusters exhibited strong shifts in their relative abundances with increasing distance from the equator. Temperature was the major environmental driver of the relative abundance of ecological clusters when Australia and Antarctica are analyzed together. Temperature, aridity, soil properties and vegetation types were the major drivers of the relative abundance of different ecological clusters within Australia. Our data supports significant reductions in the diversity of bacteria, archaea and eukaryotes in Antarctica vs. Australia linked to strong reductions in temperature. However, we only detected small latitudinal variations in soil biodiversity within Australia. Different environmental drivers regulate the diversity of soil archaea (temperature and soil carbon), bacteria (aridity, vegetation attributes and pH) and eukaryotes (vegetation type and soil carbon) across Australia. Together, our findings provide new insights into the mechanisms driving soil biodiversity in the Southern Hemisphere.
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