Dr. Mike Thiv
Molecular phytogeography of selected plant taxa of the Socotra
in collaboration with Mats Thulin (Uppsala), Tony Miller (Edinburgh), Norbert Kilian (Berlin), Ullrich Meve (Bayreuth) & Peter Linder (Zurich)
Several recent molecular phylogenetic studies have focused on the biogeography of oceanic islands. This project aims the analysisof biogeographic patterns among the flora of Socotra. This islandis located in the Indian Ocean 250 km E of the Horn of Africa.Until the late Cretaceous, it likely was connected to the Gondwananmainland. Socotra harbours some 900 species of vascular plants, ofwhich 30% are endemic. Hitherto, Socotran taxa were purported tohave biogeographic relationships to Africa, Arabia, Asia or theCanary Islands. These hypotheses were primarily based onmorphological data. Problems addressed in this project include thequestion of whether present-day Socotran plants represent Gondwananrelicts and if their occurrence on Socotra is due to vicariance or,alternatively, to long distance dispersal. The overall goal of thisproject is to reconstruct the origin of Socotran flora and thebiogeographic history of the Arabic-Socotran-East African region.Therefore, the molecular phylogenies of seven Socotran genera(Aerva-Amaranthaceae, Boswellia-Burseraceae,Campylanthus-Plantaginaceae, Echidnopsis-Apocynaceae,Kleinia-Asteraceae, Seddera-Convolvulaceae undThamnosma-Rutaceae) are reconstructed and will be compared.
Haghier-Berge: Auf der Insel Sokotra: Blick vom Wadi Ayhaft aufdie Haghier-Berge.
Gurkenbaum: Der Gurkenbaum Dendrosicyos socotrana,eine Verwandte von Gurke und Kürbis, kommt nur auf Sokotra vor.
Weihrauchbaum: Die Weihrauchbäume (hier Boswelliaameero) sind Teil der Untersuchungsgruppe.
Phylogeny and habitat evolution in the European endemic Phyteuma (Campanulaceae)
in collaboration with Gerald Schneeweiss, Michael Barfuß (Vienna) & Korinna Esfeld (Stuttgart)
The rampions (Phyteuma) comprise 28 species of exclusively European distribution. We investigated the phylogeny of the genus using DNA sequence data. Phyteuma, sister to Physoplexis, consists of two major clades. The first is characterised by globose inflorescences. The second clade comprises largely non-alpine taxa with mostly ovoid or cylindrical inflorescences. Evolution of several traits, in particular chromosome base number and habitat preferences, is assessed using maximum likelihood and Bayesian methods of ancestral character state reconstruction. The biogeographic history of the genus is analysed using ancestral area reconstructions and molecular dating.
Studying adaptive radiation at the molecular level: a casestudy in the Macaronesian Crassulaceae-Sempervivoideae
in collaboration with Korinna Esfeld (Stuttgart), Marcus Koch (Heidelberg) and others
This project was part of the Deutsche Forschungsgemeinschaft (DFG) priority programme 1127 “adaptive radiation - origin of biological diversity”. It aims the identification of genes involved in lineage diversification in the Macaronesian Crassulaceae-Sempervivoideae (Aeonium and relatives) and mainly addresses the following questions: 1) Testing the impact of regulatory versus structural genes on the process of speciation. 2) Evaluating the influence on species diversification in this group by analyzing genes presumably affecting reproductive isolation and physiological adaptation. 3) Searching for correlations between speciation and substitution rates. Such an interdisciplinary approach can contribute to a better understanding of the processes behind evolutionary diversification and speciation.