Antarctic biodiversity surveys using high throughput sequencing: understanding landscape and communities of the Prince Charles Mountains.

Abstract

Antarctic soils are home to small, inconspicuous organisms including bacteria, unicellular eukaryotes, fungi, lichen, cryptogamic plants and invertebrates. Antarctic soil communities are distinct from other soil biota as a consequence of long-term persistence under harsh environmental conditions; furthermore their long history of isolation is responsible for a high degree of endemism. Of major concern is the establishment of non-indigenous species facilitated by human-mediated climate change and increased human activity, threatening the highly specialised endemic species. A lack of baseline information on terrestrial Antarctic biodiversity currently impairs efforts to conserve the unique but still largely unknown Antarctic biota. In this thesis I apply metagenetic high throughput sequencing (MHTS) methods to address the deficiency of biological information from remote regions of continental Antarctica, and use the data generated to explore environmental constraints on Antarctic biodiversity. In Chapter 1, I introduce current issues impeding the generation of baseline Antarctic biodiversity data and evaluate the application of using MHTS techniques. This review highlights the potential of using MHTS approaches using amplicon sequencing to retrieve Eukaryotic biodiversity information from terrestrial Antarctica. In Chapter 2, the eukaryotic diversity of three biologically unsurveyed regions in the Prince Charles Mountains, East Antarctica (PCMs) is explored. Total eukaryote biodiversity in the PCMs appears to follow an altitudinal or latitudinal trend, which is less obvious for terrestrial invertebrates. In order to apply MHTS to the study of Antarctic invertebrates, the comparative taxonomic assignment fidelities of metagenetic markers and morphological approaches are explored in Chapter 3. Fidelities of taxonomic assignments to four Antarctic invertebrate phyla differed depending on metagenetic marker, and only application of non-arbitrary sequence processing parameters resulted in these findings. In Chapter 4, I use MHTS-derived biodiversity information to explore the relationship between soil properties and invertebrate biodiversity in the PCMs. Across large spatial scales distribution of phyla Tardigrada and Arachnida and classes Enoplea (Nematoda) and Bdelloidea (Rotifera) in inland areas are constrained by terrain-age-related accumulation of salts, while other Classes (Chromadorea, Nematoda and Monogonata, Bdelloidea) are better able to tolerate high salinity. In moister, nutrient-richer and more coastal areas, this effect was less pronounced and a higher invertebrate diversity was found. The methods applied and developed in this thesis are a valuable starting point to advance the collection of biodiversity information across terrestrial Antarctica and other remote habitats. The work presented here provides examples for generation and usage of MHTS information from remote Antarctic habitats, demonstrates how biodiversity information retrieved using different metagenetic markers can be combined, developed methods for assessing the quality of MHTS markers and finally demonstrated the application of MHTS data to investigate the environmental determinants of invertebrate diversity in remote ice-free habitats. Future MHTS biodiversity studies of Antarctic terrestrial habitats should incorporate large sample numbers and use combined data from multiple genetic markers.