Tropical mountains are hot spots of biodiversity and endemism,but the evolutionary origins of their unique biotas are poorlyunderstood. In varying degrees, local and regional extinction,long... Show moreTropical mountains are hot spots of biodiversity and endemism,but the evolutionary origins of their unique biotas are poorlyunderstood. In varying degrees, local and regional extinction,long-distance colonization, and local recruitment may all contribute to the exceptional character of these communities. Also, it isdebated whether mountain endemics mostly originate from locallowland taxa, or from lineages that reach the mountain by long-range dispersal from cool localities elsewhere. Here we investigatethe evolutionary routes to endemism by sampling an entire tropical mountain biota on the 4,095-metre-high Mount Kinabalu inSabah, East Malaysia. We discover that most of its unique biodiversity is younger than the mountain itself (6 million years), andcomprises a mix of immigrant pre-adapted lineages and descendants from local lowland ancestors, although substantial shiftsfrom lower to higher vegetation zones in this latter group wererare. These insights could improve forecasts of the likelihood ofextinction and ‘evolutionary rescue in montane biodiversity hotspots under climate change scenarios. Show less
The objective of this thesis was to obtain insight into the processes that play a role in biodiversity patterns of tropical marine species by using marine lakes as a model. Marine lakes are... Show moreThe objective of this thesis was to obtain insight into the processes that play a role in biodiversity patterns of tropical marine species by using marine lakes as a model. Marine lakes are landlocked water bodies that maintain a marine character through narrow submarine connections to the sea. Two regions in Indonesia were studied: Berau (East Kalimantan) and Raja Ampat (West Papua). The following questions were addressed: 1. What are the different types of marine lakes in Indonesia? 2. Are the species assemblages in marine lakes distinct from those in the adjacent coastal environments? 3. To what extent are the populations in the lakes isolated? 4. Can marine lakes in Indonesia be considered natural laboratories of evolution? There is a large diversity in types of marine lakes and many more remain to be documented in Indonesia. The spatial variation in sponge species composition in marine lakes, coastal mangroves and coral reefs show that marine lakes contain three groups of sponge species: (a) widespread species known from various locations in Indo-Pacific reefs, (b) lake species that only occur in lake systems, (c) endemic species restricted to a single lake. The patterns of genetic variation found in the marine lake populations are generally consistent with populations in isolated environments. The lakes appear to be both cradles and refuges of diversity Show less
