FORMER STAFFCatarina Rydin
Postdoctoral Researcher
Contact
Phone: +46-8-163-671 Fax: +46-8-165-525 E-mail: catarina.rydin@botan.su.seResearch area
Catarina Rydin worked within the department on the origin and evolution of seed plants. Her project examined the diversity, phylogeny and evolutionary history of seed plants, focusing on the Gnetales. She integrated results from molecular data and morphology of extant plants with information from fossils in order to investigate character evolution and document morphological variation through time and space. With phylogenies as a framework Catarina studied correlations between cladogenetic events, morphological variation and biogeographical patterns.The origin and evolution of Gnetales is currently under intensive debate. Gnetales have been associated with angiosperms or with conifers, but their morphology is difficult to interpret and relationships and homology with other seed plants have never been fully understood. Recent species consist of three distinct genera. Gnetum (about 40 species) are lianas with large angiosperm-like leaves occurring in tropical rainforests of Africa, Asia and South America. Ephedra (about 40 species) are shrubs with reduced leaves, inhabiting dry temperate regions mainly in the northern hemisphere. Welwitschia (1 species in the deserts of Namibia) has a unique morphology and consists of two evergreen leaves and a woody scalebody.The Gnetales are a relict group of seed plants, which was particularly diverse during the Mesozoic. The rapidly expanding information on Mesozoic diversity has provided new insights, mainly on the evolutionary history of Ephedra but also of the Gnetum-Welwitschia clade. Ephedra and Ephedra-like fossils have been reported from China, South America, North America and Europe, and recent findings document the presence of the Welwitschia lineage in equatorial Gondwana. Fossils from the Yixian Formation in China, preserved as compressions or impressions in silty mudstone of Barremian to Aptian (Early Cretaceous) age, are central to the project. The material provides unique information on overall habit of the plants and includes fossils that are closely related to Ephedra, but also specimens possibly related to Gnetum, which is rare and interesting. We further investigate coalified seeds from the Early Cretaceous of Portugal and North America, with preserved anatomical details including in situ pollen.Catarina is now employed by the Department of Botany and Stockholm University where she is working on the phylogeny, diversity and biogeography of Rubioideae in collaboration with Jenny Smedmark and Birgitta Bremer. This recently initiated project involves phylogeny, biogeography and trait evolution of some basal groups within Rubioideae, Rubiaceae. Initially, we investigate relationships between approximately 1350 species assigned to the tribes Urophylleae, Ophiorrhizeae, Lasiantheae and Cossareae. Using the resulting phylogenies as framework we will estimate divergence times and address questions on evolutionary and ecological mechanisms behind morphological variation, species richness and geographical patterns.
Project
Phylogeny and evolution of Gnetales
Publications
Publications
Print page
