Gall crabs (Crustacea : Cryptochiridae) are small, coral-dwelling crabs that live in obligate association with their host corals (Scleractinia), on which they rely for food and shelter. They have... Show moreGall crabs (Crustacea : Cryptochiridae) are small, coral-dwelling crabs that live in obligate association with their host corals (Scleractinia), on which they rely for food and shelter. They have been recorded from shallow and deeper waters (over 500 m), but the majority of the species live in reef corals in the photic zone. The highest number of species is recorded from the Indo-West Pacific, where coral diversity is highest. This PhD thesis deals with various aspects of their evolution and diversification; four species are described as new to science, and the host specificity, biogeography, distribution and reproductive morphology of gall crabs are studied. In addition, the close association between gall crabs and corals allowed for studies on (cryptic) speciation and possible coevolution. Results show that the observed coevolutionary events should most probably be ascribed to sequential evolution, which indicates that the phylogeny of the gall crabs has been directed by the evolution of the corals. Show less
Population growth and the drop in the returns from the major cash crop (coffee) for small farmers are the main drivers that have influenced the farming systems and mobility of farmers in the... Show morePopulation growth and the drop in the returns from the major cash crop (coffee) for small farmers are the main drivers that have influenced the farming systems and mobility of farmers in the Western Highlands of Cameroon (WHC). The main objective of this research activity was to determine the interactions between farming systems and human mobility in the WHC. A comparative study was conducted through household and field surveys in three villages and conceptualized based on the systems approach. The different types of mobility were influenced by household social factors, the quest for ‘high valued' farm plots and hired labour. Urban-rural migration contributed to occupation diversification and social mobility. The sustainability factor was a function of land use intensity, intensity of off-farm inputs, the household adjustment factor and mobility of the household. The sacred groves were rich in plant diversity of varied ecological and economic importance. Nitrogen mining was common at all levels of the farming system. These determinants and types of mobility claims are pertinent to the research area; the sustainability results of the farming systems reflect the reality on the ground; the nutrient flux evaluated at the crop and farm levels constitute a valuable database for future research. Show less
The Philippine crocodile is a critically endangered species, endemic to the Philippine Islands. Indiscriminate hunting, the use of destructive fishing practices and the conversion of wetland... Show moreThe Philippine crocodile is a critically endangered species, endemic to the Philippine Islands. Indiscriminate hunting, the use of destructive fishing practices and the conversion of wetland habitat into rice fields continue to threaten the few remaining Philippine crocodile populations in the wild. This thesis describes the in-situ conservation efforts for the species in the northern Sierra Madre on Luzon by the Mabuwaya Foundation. Traditions, emotions and ethics form important reasons for rural communities in the northern Sierra Madre to support the conservation of the Philippine crocodile in their surroundings. But in contemporary conservation discourses such an argument is easily dismissed as hopelessly romantic, elitist or even irrational. In fact raising awareness, fostering pride and empowering rural communities to protect the resources they need and value is, in the end, a more pragmatic, pro-poor and rea listic strategy to mobilize local support for the protection of the Philippine crocodile than a narrow focus on generating economic incentives. Conservation efforts can be significantly strengthened if cultural and intrinsic values are taken into account. Pride, interest and respect offer the best hope for the survival of the Philippine crocodile in the 21st century. Show less
Forest damselflies (family Platystictidae) are widespread in southeast Asia from Sri Lanka to New Guinea, and are also known from Central America and the northern part of South America. The larvae... Show moreForest damselflies (family Platystictidae) are widespread in southeast Asia from Sri Lanka to New Guinea, and are also known from Central America and the northern part of South America. The larvae of most species live in small streams or seepages under forest canopy. Adults are found hanging from the tips of leaves or twigs along streams. The family is thought to have evolved more than 100 million years ago. Only 213 species are known worldwide, of which the author described 46 as new to science. Although most species are remarkably similar in general appearance, they show significant variation in structural details such as wing venation, pronotum, and secondary genitalia of the male. The group is ideal for biogeographical studies, since most species have small distributional ranges. A reconstruction of the phylogeny shows that several ancient lineages occur along the margin of the Indian Plate. Although Platystictidae are not known from Africa, it is hypothesized that the family evolved on that continent. The ancestors of the subfamilies Platystictinae and Sinostictinae drifted with India to Asia between 100 and 45 Ma. A scenario of the historical biogeography of the Platystictinae is described in relation to the palaeogeography of southeast Asia since the Eocene. The subfamily Palaemnematinae most likely dispersed from Africa to the New World via Europe and the ‘North Atlantic Land Bridge’. 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
Land use change results from the interaction between the human and the natural system and therefore various scientific disciplines have developed paradigms and methods to study land use change.... Show moreLand use change results from the interaction between the human and the natural system and therefore various scientific disciplines have developed paradigms and methods to study land use change. However, these disciplinary approaches can only cover part of the complex system of land use change. The objective of this dissertation is to develop interdisciplinary methodologies to identify and integrate factors that are important in the land use system to describe and model the land use system in a comprehensive manner. The methodological challenges that are addressed in this study include bridging differences in spatial and temporal scales and organisational levels, identification of appropriate units of analysis, combining different disciplinary paradigms and developing new paradigms that unify the disciplines in one concept. The development of these methods is illustrated with a case study in a municipality in the Philippines, where in the past century large land use changes have taken place through commercial logging and expansion of agriculture. To make projections of future land use in the area models were constructed for the case study. In this dissertation it is the combination of approaches that have led to a greater understanding of the land use in the study area. Especially moving between empirical, inductive methods and theoretical, deductive methods has proven to be a useful approach to stimulate theory building. Show less
