This thesis presents a detailed molecular phylogenetic and biogeographic study of the Spathelioideae clade, a group of seven small Sapindalean genera with remarkable morphological diversity. The... Show moreThis thesis presents a detailed molecular phylogenetic and biogeographic study of the Spathelioideae clade, a group of seven small Sapindalean genera with remarkable morphological diversity. The systematic placement of these genera has always been in dispute and the results of this thesis show that Spathelioideae are a monophyletic sister clade to the Rutaceae family. Except for the South American and Caribbean genus Spathelia, all Spathelioideae genera are monophyletic. The South American species have been transferred to a resurrected genus Sohnreyia accordingly. Molecular dating analyses suggest an origin of Spathelioideae in the Late Cretaceous. Assuming a palaeotropic origin of Rutaceae, the stem lineage of Spathelioideae might have originated in Central western and central Africa. The divergence of a Neotropical and a Palaeotropical lineage of Spathelioideae might be explained by long-distance dispersal during the Late Cretaceous or Palaeocene. Within the Neotropical clade, one dispersal event to the Caribbean occurred possibly via a landbridge or a series of islands. Sea level changes in the Pleistocene have isolated and connected landmasses in the Caribbean and might have been triggers for speciation of the genus Spathelia. Within the Palaeotropic clade, dispersal events from Africa to the Mediterranean & Canary Islands, Madagascar, and South-East Asia occurred. Show less
Molecular phylogenetic studies focused on the genus Phyllanthus L. (Phyllanthaceae) showed that Sauropus Blume (including Synostemon F.Muell.) and its related genera Breynia J.R.Forst. & G... Show moreMolecular phylogenetic studies focused on the genus Phyllanthus L. (Phyllanthaceae) showed that Sauropus Blume (including Synostemon F.Muell.) and its related genera Breynia J.R.Forst. & G.Forst. and Glochidion J.R.Forst. & G.Forst. should be united with Phyllanthus to create a monophyletic genus. The relationships within Sauropus and its relationship with Breynia were studied to test/corroborate such a broad definition of Phyllanthus. The molecular phylogenetic analyses show that Sauropus in the broad sense is composed of two distinct groups, the former Australian Synostemon and the Southeast Asian Sauropus in the strict sense with the monophyletic Breynia embedded in the latter. As the phylogeny of the species rich Phyllanthus is still far from completed and the results here strongly support the distinction of monophyletic groups such as Glochidion, former Synostemon, and Sauropus/Breynia. These genera are recognisable, while union with Phyllanthus (suggested by Hoffmann and co-authors in 2006) will turn the latter into an unrecognisable monolithic giant of a genus. It is a much better strategy to use the complete phylogeny of Phyllanthus to render it into smaller, monophyletic genera that can be characterized. The present study shows Synostemon has to be recognised again on generic level. Breynia, the older name, is nested within Sauropus, leading us to transfer the latter to Breynia. Within this broadened Breynia, two subgenera and two sections are distinguished, subgenus Sauropus and subgenus Breynia with section Cryptogynium and section Breynia under the latter. Show less
