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SUMMARY:Evolutionary History of the Antarctic Flora - Elise Biersma
DTSTART:20130620T143000Z
DTEND:20130620T145500Z
UID:TALK45766@talks.cam.ac.uk
CONTACT:Megan Cooper
DESCRIPTION:Ice sheet reconstructions and glaciological modelling suggest 
 that ice sheets covered most terrestrial areas of Antarctica during the La
 st Glacial Maximum (LGM\; around 22–17 ka)\, as well as previous Miocene
 \, Pliocene and Pleistocene glaciations. This suggests that most pre-Neoge
 ne (older than 23 Ma) terrestrial life in Antarctica would have been wiped
  out. However\, recent Antarctic classic and molecular biogeographic resea
 rch suggests that much of the contemporary Antarctic terrestrial biota has
  a long-term history in situ on the continent\, Peninsula and associated a
 rchipelagos\, with timescales of evolutionary persistence ranging through 
 pre-LGM (Pleistocene)\, Pliocene and Miocene\, to Gondwana-breakup.\nBryop
 hytes (mosses)\, a major component of the Antarctic flora\, currently stan
 d distinct from these patterns\, with classical taxonomic studies suggesti
 ng species endemism levels of only 5-10%. Their low endemism levels and co
 ntemporary distribution patterns suggest that bryophytes\, unlike all othe
 r groups considered were driven extinct during Pleistocene glacial maxima 
 and\, therefore\, today’s biota are recent colonists. Alternatively\, br
 yophytes could have a long-term history on the continent\, but their evolu
 tionary divergence processes may be much slower than in the terrestrial bi
 ota considered in most other studies. \nAs yet\, molecular approaches have
  not been applied widely to this group in Antarctica\, with the few studie
 s available providing contradictory information to that of classical taxon
 omy.  Resolution of the evolutionary history of bryophytes within Antarcti
 ca\, 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 Antarcti
 ca\, thereby placing Antarctic plant biogeography firmly both into the con
 text of that of the surrounding southern landmasses\, and that of the glac
 iation history of Antarctica itself.\nThis study focuses on several abunda
 nt moss species with specific distribution patterns (endemic\, bipolar\, c
 osmopolitan). Three to four genes per taxon are being targeted\, including
  nuclear\, chloroplast and mitochondrial DNA. ‘Relaxed phylogenetic’ m
 ethods incorporated within the program BEAST v1.4.17 are being applied to 
 estimate rates of molecular evolution\, divergence times\, and phylogeneti
 c relationships of the target taxa. \n
LOCATION:Biffen Lecture Theater\, Department of Genetics
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