Oberprieler, Christoph , Greiner, Roland , Lo Presti, Rosa Maria .
Speciation in Mediterranean Compositae-Anthemideae – climatic and geographical differentiation, hybridisation, and polyploidy.
The Mediterranean region plays a paramount role in the taxonomic diversity of the Compositae (Asteraceae) tribe Anthemideae. The tribe is represented here and in the adjacent areas of Europe and Asia with around 620 of its presumptive c. 1750 species and 52 of its 111 genera. The majority of these taxa form a well-supported monophyletic group around the species-rich genera Achillea, Anthemis, Leucanthemum, Tanacetum, and Tripleuropsermum. We have used both macro- and microevolutionary approaches to study the driving forces behind speciation processes in this actively evolving group of higher plants. In the genus Anthemis, the combination of reconstructions of the spatial-temporal diversification of the genus with eco-climatological niche-modelling shows that large-scale differentiation patterns triggered by geological forces appear to have influenced the evolutionary history of the genus in a rather constant manner over the last 12 Ma, whereas climatic forces seem to have played an important role in two phases of the radiation process: at around 9 Ma, when the area experienced the onset of a trend towards aridification, and during the last 3.5 Ma, with the establishment of the typical Mediterranean climate and the influence of Pleistocene climate oscillations. Microevolutionary reconstructions in the A. secundiramea-group in the central Mediterranean indicate that hybridisation is a further factor influencing the diversity of the tribe. On the other hand, the importance of polyploid speciation is impressively demonstrated by the genus Leucanthemum, which constitutes a polyploid complex with 43 species representing an uninterrupted series of diploid to dodecaploid chromosome numbers. Crossing experiments carried out along with phylogeographical reconstructions (AFLPs, sequencing of nuclear and chloroplast markers) in the L. pluriflorum-group indicate high levels of incongruence between traditional taxonomy on the species level and its genetic background (multiple origin of polyploids, gene flow among ploidy levels).
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1 - University of Regensburg, Institute of Botany, Universitätsstr. 31, Regensburg, D-93040, Germany
bioclimatic niche analysis
Presentation Type: Oral Paper:Papers for Sections
Location: 556A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 3:45 PM