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2 Posts tagged with the palaeoclimate tag
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Eocene.jpg

Fridgeir Grimsson

Department of Palaeontology, University of Vienna

 

Tuesday 25 March - 4.00 pm

Earth Sciences Seminar Room
(Basement, WEB 05, the previous Mineralogy Seminar Room)
 
Oldest records of many modern north-temperate woody angiosperm genera are from the Eocene. However, the precise time and place of origin of individual tree genera that play important roles in modern temperate forest ecosystems has largely remained unresolved. One hypothesis about the origin of modern temperate woody elements in the northern hemisphere was proposed in the late 19th century by Adolf Engler, who suggested that many modern temperate tree genera originated in Arctic areas and migrated southwards in the course of the Cenozoic when global climate cooled.

 

The final objective of the present study is to test the validity of Engler’s (1882) concept of the “arctotertiary element”, that is, to determine whether early Cenozoic high latitude floras were the cradle of a number of tree genera that now dominate north-temperate mid-latitude forests. To achieve this, the systematic affinities of  pollen from Paleocene and Eocene sediments of western Greenland and the Faröe Islands are being assessed using combined light and scanning electron microscopy. Macrofossils from the same areas housed in existing museum and university collections are also under study, and new material has been collected in the field. By combining evidence from the palynofloras and the revised macrofloras, the phylogenetic affinities of the recognized plant taxa are being established in order to determine the proportion of extinct lineages and co-occurring extant genera, representing the “arctotertiary element” in the fossil floras.

 

 

For additional details on attending this or other seminars see http://www.nhm.ac.uk/research-curation/seminars-events/index.htm

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Life Sciences Seminar


Inferring the diversification of land plants at and in the shadow of the Roof of the World

 

Harald Schneider

Plants, Dept. of Life Sciences, NHM

 

Wednesday 12 of December 11:00
Sir Neil Chalmers seminar room, Darwin Centre LG16 (below Attenborough studio)


Orogenic events in earth history, e.g. mountain formation, have made a profound impact on the assembly of biological diversity. For example, recent studies of the biodiversity of South America recovered strong evidence that the Cenozoic rise of the Andeans triggered the rapid diversification of many lineages of vascular plants.

 

However, relatively little attention has been given to the effect of the rise of the Himalaya on plant diversity. The rise of this mountain chains were triggered by the collision of the Indian tectonic plate with the Eurasian continent 70 million years ago but major uplifts date back to more recent times. Especially the rather recent formation of the Qinghai-Tibetan plateau, around 3-4 million years ago, had a considerable impact on the monsoon climates in South East Asia. Thus the rise of this plateau affected not only the evolution of plants adapted to the alpine conditions at the high altitudes of the Himalaya but also the expansion of xeric habitats in central Asia and the enhanced monsoons affecting South East Asia and South Asia.

 

The hypothesis of the impact of the rise of the Himalaya on plant diversity in South East Asia is studied employing mainly phylogenetic approaches that incorporate divergence time estimates, ancestral area reconstruction, inference of niche evolution, and estimates of diversification rates. The analyses also incorporate evidence from micro-paleontological research.

 

Comparative assessment of the existing and newly generated phylogenetic hypotheses for a wide range of angiosperms and ferns recovered evidence supporting the hypothesis of a substantial impact of the rise of the Qinghai-Tibetan plateau on the assembly of lineage diversity. This result is consistent with palaeoclimate reconstructions that are based on pollen and spore record. In comparison, the recovered patterns indicate the involvement of different processes in response to the Cenozoic mountain formations in South America and South East Asia.

 

The presentation summarises research that was carried out during my time as a senior visiting professor of the Chinese Academy of Sciences. Besides the presentation of the results of the research, I will also touch on issues related to the current research conditions in China.

 

Harald Schneider

 

 

 

For additional details on attending this or other seminars see http://www.nhm.ac.uk/research-curation/seminars-events/index.html