Mollusca form an important animal phylum that first appeared in the Cambrian, and today is,after Arthropoda, the second largest animal phylum, with more than 100,000 extant species(Bieler, 1992,... Show moreMollusca form an important animal phylum that first appeared in the Cambrian, and today is,after Arthropoda, the second largest animal phylum, with more than 100,000 extant species(Bieler, 1992, Brusca and Brusca, 2003), with the class Gastropoda accounting for 80% of the extant species in the Mollusca. Despite its species-richness, a generalised gastropod shell architecture is maintained because of conserved developmental processes. All of the shelled gastropods grow by adding, in a unidirectional accretionary way, shell material with the mantle edge organ, usually at different deposition rates around the existing aperture. This shell ontogeny, or to be more specific aperture ontogeny, gives the general spiral form for the shells. However, spiral forms can vary when there are changes in any one of the aspects in the aperture ontogeny profiles, namely, the rate and direction of shell deposition around the aperture, size and shape of the aperture (i.e. mantle edge), and the total length of the shell ontogeny processes. The interplays between these developmental parameters have generated a great diversity in shell form, for which taxonomists and evolutionary biologist are now trying to accurately characterise and to understand with regard to its evolution.This thesis reveals several hitherto unknown aspects of Plectostoma shell forms,in terms of the developmental homology, the aperture ontogeny profile, anti-predation functionality, and evolutionary pattern in shell characters and ontogenetic morphospace evolution. In fact, these are the issues that have been targeted by biologists for centuries in order to improve the way shell shape is characterised and to improve understanding of shell form evolution. Show less
Based on the digitized herbarium records housed at the National Herbarium of the Netherlands I developed high spatial resolution patterns of Borneo's botanical richness, endemicity, and the... Show moreBased on the digitized herbarium records housed at the National Herbarium of the Netherlands I developed high spatial resolution patterns of Borneo's botanical richness, endemicity, and the floristic regions. The patterns are derived from species distribution models which predict a species occurrence based on the identified relationships between species recorded presences and the ecological circumstances at those localities. A new statistical method was developed to test the species distribution models. Several areas of high richness and endemicity were added to the list of previous known ones. Furthermore, the lowland rain forest of Borneo, previously recognized as one floristic region, in fact harbours at least four (and possibly six) different floristic regions. Show less
This dissertation deals with Mualang, an Ibanic (Malayic-Dayak) language spoken in the interior of western Kalimantan (Borneo), Indonesia. Given the relatively large number of speakers ... Show moreThis dissertation deals with Mualang, an Ibanic (Malayic-Dayak) language spoken in the interior of western Kalimantan (Borneo), Indonesia. Given the relatively large number of speakers (approximately 40,000 people), and due to its fairly isolated geography and some well-maintained socio-cultural traditions, the study of the language considerably broadens our knowledge of the Ibanic language family and the Malayic language group in general. Western Borneo has been posited as a possible homeland-candidate of Proto Malayic speakers. Therefore, linguistic contributions about inland languages in areas such as that of the Mualang language and people will provide Austronesian linguists with more information regarding this issue. This study presents a descriptive account of the grammar of Mualang covering the major features of its sound system, word and sentence structure as well as text grammar topics. The description results from a combination of textual analysis, elicitation and participant observation. The grammar is supplemented by wordlists and an extensive collection of glossed and translated texts. Show less
In the last two decades El-Niño-induced fires have caused widespread destruction of forests in East Kalimantan. The 1997-98 fires were the most extensive yet. The post-fire situation was studied in... Show moreIn the last two decades El-Niño-induced fires have caused widespread destruction of forests in East Kalimantan. The 1997-98 fires were the most extensive yet. The post-fire situation was studied in detail by field assessments and high-resolution SAR-images. My results show that rain forests are better able to conserve their high plant diversity than has been assumed because of the network of unburnt remnant forest, large remnant trees, and abundant tree regeneration. These elements were present in burnt forests throughout the burnt region. Subsequent destructive human activities, rather than El-Niño fires themselves, are the major threat to these forests' plant diversity. Show less
