The largest genus within the Phyllanthaceae family is a group called Phyllanthus L. Recent studies have shown, that Phyllanthus is paraphyletic with the genera Glochidion, Breynia and Synostemon... Show moreThe largest genus within the Phyllanthaceae family is a group called Phyllanthus L. Recent studies have shown, that Phyllanthus is paraphyletic with the genera Glochidion, Breynia and Synostemon nested within it. In this thesis, I study the evolution and systematics of Phyllanthus and how to solve the apparent paraphyly. First we explore past morphological subgroups to come to a subdivision, which was tested using molecular phylogenetics. Several species of Phyllanthus are also used in traditional medicine and by utilizing the living collections of the Hortus botanicus Leiden, we tested for antibacterial and antifungal bioactivity. The phylogeny resulting from this study is used to study the historical biogeography and diversification of the tribe and to propose a new classification where Phyllanthus is separated into several smaller genera. Show less
The thesis is about the study of shell evolution of the Hydrocenidae of the genus Georissa. This thesis started with a general overview on the evolutionary process of animals due to ecological... Show moreThe thesis is about the study of shell evolution of the Hydrocenidae of the genus Georissa. This thesis started with a general overview on the evolutionary process of animals due to ecological changes. This study has revealed that the Bornean Georissa are more diverse than previously anticipated. I did the taxonomic revision of the genus Georissa, and discussed the morphological features, phylogenetic relationships, and the biogeographic distribution of the genus in Malaysian Borneo. Also, I studied the shell character evolution of the Bornean Georissa in a phylogenetic framework. Based on the phylogeny, I found convergence in the formation of scales. Additionally, I discussed the differentiation of size and coloration of the Bornean Georissa in dependence on different habitats. Show less
The northwest corner of South America harbours a region of spectacular and mysterious landscapes called Pantepui. Due to its ancient age and fragmented topography Pantepui has been assumed to be an... Show moreThe northwest corner of South America harbours a region of spectacular and mysterious landscapes called Pantepui. Due to its ancient age and fragmented topography Pantepui has been assumed to be an ideal nursery of speciation, and tepuis (table mountains) have been seen as potential inland counterparts to oceanic islands. Tepuis are often called __islands in the sky__ and their summits seem indeed ideal candidates to harbour relict species, isolated from the rest of the world for millions of years. However our knowledge about the origin and diversification of the Pantepui biota is at least as fragmentary as the tepui physiography itself. This led some authors to consider the origin of local biodiversity and endemism a still-unresolved evolutionary enigma. This work aims to (1) better understand the species diversity, the evolutionary history, the dynamics of biotic interchanges between tepui summits, and the patterns of endemism of the fauna in the Pantepui region, using morphological analyses and molecular phylogenies of six amphibian and reptile taxa; (2) provide new insights in the timing of the geomorphological evolution of the tepuis in the light of amphibian and reptile species diversification inferred from molecular phylogeny reconstructions and estimates of divergence time. Show less
