Ground-truthing Phylotype Assignments for Antarctic Invertebrates

Abstract

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...