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Evolutionary History of the Antarctic Flora

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Ice sheet reconstructions and glaciological modelling suggest that ice sheets covered most terrestrial areas of Antarctica during the Last Glacial Maximum (LGM; around 22–17 ka), as well as previous Miocene, Pliocene and Pleistocene glaciations. This suggests that most pre-Neogene (older than 23 Ma) terrestrial life in Antarctica would have been wiped out. However, recent Antarctic classic and molecular biogeographic research suggests that much of the contemporary Antarctic terrestrial biota has a long-term history in situ on the continent, Peninsula and associated archipelagos, with timescales of evolutionary persistence ranging through pre-LGM (Pleistocene), Pliocene and Miocene, to Gondwana-breakup. Bryophytes (mosses), a major component of the Antarctic flora, currently stand distinct from these patterns, with classical taxonomic studies suggesting species endemism levels of only 5-10%. Their low endemism levels and contemporary distribution patterns suggest that bryophytes, unlike all other groups considered were driven extinct during Pleistocene glacial maxima and, therefore, today’s biota are recent colonists. Alternatively, bryophytes could have a long-term history on the continent, but their evolutionary divergence processes may be much slower than in the terrestrial biota considered in most other studies. As yet, molecular approaches have not been applied widely to this group in Antarctica, with the few studies available providing contradictory information to that of classical taxonomy. Resolution of the evolutionary history of bryophytes within Antarctica, and confirmation of if and how this differs from all other groups of terrestrial biota, is now critical for advancing Antarctic biogeographic and evolutionary understanding. The study will also provide important new evidence for the routes of bryophyte colonisation into and within Antarctica, thereby placing Antarctic plant biogeography firmly both into the context of that of the surrounding southern landmasses, and that of the glaciation history of Antarctica itself. This study focuses on several abundant moss species with specific distribution patterns (endemic, bipolar, cosmopolitan). Three to four genes per taxon are being targeted, including nuclear, chloroplast and mitochondrial DNA . ‘Relaxed phylogenetic’ methods incorporated within the program BEAST v1.4.17 are being applied to estimate rates of molecular evolution, divergence times, and phylogenetic relationships of the target taxa.

This talk is part of the Plant Sciences Research Seminars series.

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