Abstract
The biodiversity of ice-free areas in Antarctica has been of interest to scientists of different disciplines for many years. Histories, real and imagined, about the Terra Australis Incognita date back to the time of Aristotele (384 – 322 BC). But it was not until the beginning of the 19th century that the first actual records of Antarctic life became available. Since then, two centuries of intensive research have significantly helped us to track the geological evolution of the continent and its living organisms. Up until around 180 million years ago, Antarctica was part of Gondwana, and with temperatures on average 15°C higher than today, it was home to diverse forms of life. However, after the breakup of Gondwana, Antarctica took its current position at the South Pole, and, later in the Cenozoic, the glaciation of the continent began. With the development of the ice-sheets, most of the Antarctic biota went extinct, and today only about 0.5 % of Antarctica is ice-free. The ice-free areas, found in islands and archipelagos around the coast, and valleys and mountains in land, is where the Antarctic terrestrial biota is mostly found. Mosses, lichens, microalgae, liverworts, mites, springtails, rotifers, tardigrades, and nematodes are the main flora and fauna of Antarctica. Investigations on the systematics, physiology, and ecology of these taxa have resulted in a broad understanding of their biogeography in the continent. Yet, what we know about the biodiversity of Antarctica will certainly increase when molecular tools are used to circumvent the difficulties of distinguishing taxa morphologically, and to survey geographic locations that have been underrepresented in previous surveys.
Environmental DNA (eDNA) metabarcoding is a useful approach for assessing biodiversity in remote areas and in diverse organisms. eDNA metabarcoding is a molecular technique used to simultaneously identify multiple taxa from an environmental sample, which may be from soil, water, faeces, or other material. Until now, eDNA metabarcoding has mostly been used in terrestrial ecosystems to study microbial taxa, and thus its effectiveness for studying plants and animals requires evaluation.
This thesis encompasses three eDNA metabarcoding investigations on the diversity and distribution of plants and animals in Prydz Bay, Ingrid Christensen Coast, East Antarctica.
In the first study, the effects of eDNA metabarcoding analyses on the estimation of eukaryote diversity in soil samples from Stornes Peninsula were analysed. The success in finding common Antarctic taxa validates the use of soil eDNA metabarcoding to study Antarctic terrestrial biodiversity. The results of this experiment also showed that the choice of protocol can have a significant effect on the estimate of eukaryote diversity.
In the second study, the diversity of plants and animals in Prydz Bay was investigated using the soil eDNA metabarcoding recommended in the first experiment. These findings provide valuable insights into the biodiversity of historically under-surveyed areas in Antarctica. The need for expanding the reference databases for Antarctic terrestrial taxa is emphasized by the low taxonomic coverage achieved.
In the third study, the effects of emperor penguins (Aptenodytes forsteri) on the composition of communities in ice-free areas in Amanda Bay was investigated through eDNA metabarcoding. Distinctive eDNA signals across sites showed that emperor penguins might affect the abundance of taxa but not their presence or absence in the ice-free areas of Amanda Bay.
This thesis presents a contribution towards our knowledge of the flora and fauna of ice-free areas in East Antarctica. The findings validate the use of eDNA metabarcoding protocols to investigate the Antarctic terrestrial biodiversity. The results also provide insights into the ecological interactions triggering the composition of communities in Antarctic ice-free areas. Finally, the thesis highlights the lack of genetic reference data as one of the key limitations for future eDNA metabarcoding research in Antarctica.